Tags

adapters

Fine-Tuning and LoRA Fine-tuning, instruction tuning, parameter-efficient adaptation, LoRA adapters, data quality, evaluation, merge behavior, and rollback.

administration

Time, Hostname, and Identity Time synchronization, timezone, hostname, machine-id, DNS identity, certificates, logs, Kerberos sensitivity, and Ubuntu host identity operations. Users, Permissions, and sudo Linux identities, groups, file modes, ownership, sudo, service users, locked accounts, ACLs, and permission troubleshooting on Ubuntu.

advanced

Advanced Agents Advanced agent engineering with ReAct, planning, reflection, tool routing, multi-agent systems, durable execution, memory, sandboxing, approval workflows, trajectory evaluation, and failure recovery. Advanced Fine-Tuning Advanced fine-tuning with full tuning, LoRA, QLoRA, adapter composition, multi-adapter serving, dataset mixing, long-context tuning, packing, catastrophic forgetting, and safety-preserving releases. Advanced Inference and vLLM Advanced LLM inference with vLLM, PagedAttention, continuous batching, disaggregated prefill, chunked prefill, speculative decoding, prefix caching, KV-cache math, tensor and pipeline parallelism, quantized serving, LoRA serving, and autoscaling. Advanced ML Architectures Advanced model architectures including Mixture of Experts, retrieval-augmented models, state space models, diffusion transformers, sparse attention, long-context architectures, and encoder-only, decoder-only, and encoder-decoder tradeoffs. Advanced ML Observability Advanced ML observability with drift detection, data quality monitoring, online evals, human feedback loops, trace schemas, prompt/retrieval/model/tool observability, safety monitoring, cost monitoring, and incident review templates. Advanced RAG Advanced retrieval-augmented generation with hybrid retrieval, query planning, multi-hop retrieval, reranker architectures, GraphRAG, context compression, citation verification, agentic RAG, retrieval evals, and RAG security. ML Evaluation Mastery Advanced ML evaluation with unit evals, golden sets, model-graded evals, human evals, pairwise preference evals, safety evals, regression gates, slice metrics, statistical confidence, and contamination controls.

agents

Advanced Agents Advanced agent engineering with ReAct, planning, reflection, tool routing, multi-agent systems, durable execution, memory, sandboxing, approval workflows, trajectory evaluation, and failure recovery. ML Agents and Tool Use Agentic ML systems with planning loops, tools, state, memory, idempotency, guardrails, human approval, and evaluation.

ai

Machine Learning Machine learning systems study guide from ML 101 through advanced concepts: math, classical ML, deep learning, transformers, LLM training, fine-tuning, RAG, agents, serving, vLLM, MLOps, security, evaluation, performance, and governance.

alignment

LLM Training Lifecycle LLM lifecycle from pretraining and continued pretraining to SFT, RLHF, DPO, RLAIF, preference data, synthetic data, data filtering, and stage-specific evaluation. ML Alignment and Evaluation Alignment, evaluation, RLHF, preference tuning, DPO, safety policy, red teaming, regression gates, calibration, and monitoring.

amd

Linux GPU Drivers Linux GPU driver stacks for AMD and NVIDIA, including kernel modules, firmware, Mesa, ROCm, CUDA, nvidia-smi, Secure Boot, containers, and troubleshooting.

architecture

Core Concepts Kubernetes object model, controllers, scheduling, node agents, and reconciliation.

architectures

Advanced ML Architectures Advanced model architectures including Mixture of Experts, retrieval-augmented models, state space models, diffusion transformers, sparse attention, long-context architectures, and encoder-only, decoder-only, and encoder-decoder tradeoffs.

attention

Transformer Internals Transformer internals covering tokenization, embeddings, positional encodings, RoPE, self-attention, multi-head attention, MLP blocks, LayerNorm/RMSNorm, decoder-only models, KV cache, context windows, and MoE basics.

audio

Multimodal ML Multimodal ML with vision, audio, speech-to-text, text-to-speech, vision-language models, image embeddings, OCR pipelines, multimodal RAG, and video model basics.

authentication

Identity and Access Identity-provider, federation, SSO, SAML, OAuth, OpenID Connect, JWT, token validation, and access-control study guide.

authoritative-dns

Authoritative DNS and Zones Zones, delegations, NS records, SOA serials, glue, apex constraints, wildcard behavior, and authoritative debugging.

authorization

Identity and Access Identity-provider, federation, SSO, SAML, OAuth, OpenID Connect, JWT, token validation, and access-control study guide. Istio Security, mTLS, and Policy Istio workload identity, mTLS, PeerAuthentication, AuthorizationPolicy, RequestAuthentication, JWT validation, trust domains, and policy debugging.

automation

ML Agents and Tool Use Agentic ML systems with planning loops, tools, state, memory, idempotency, guardrails, human approval, and evaluation. Network Boot and Automated Provisioning PXE, UEFI HTTP Boot, iPXE, DHCP, TFTP, automated Linux installs, Ubuntu autoinstall, cloud-init NoCloud, Kickstart, bare-metal provisioning, and troubleshooting. Scheduled Automation Cronjobs, anacron, systemd timers, user timers, environment pitfalls, idempotent jobs, logs, locking, and automation troubleshooting.

backup

Linux Backup and File Transfer Linux backup and transfer notes covering rsync, scp, snapshot backups, consistency, restore testing, exclusions, permissions, and automation.

backups

Linux Operations Examples Practical Linux examples for systemd services, timers, rsync snapshot backups, and nftables host firewalls.

benchmarking

Inference Benchmarking Benchmark methodology for LLM inference with warmup, prompt/output distributions, concurrency sweeps, TTFT, ITL, throughput, quality gates, and benchmark anti-patterns.

bgp

BGP and Dynamic Routing BGP fundamentals for operators: ASNs, peering, route advertisement, route selection, communities, ECMP, anycast, and failure modes.

block-devices

Linux Block Devices and Partitioning Linux block devices, NVMe and SCSI naming, partitions, GPT, UUIDs, labels, udev, stable device paths, and safe disk identification.

boot

Linux Boot and Userspace Firmware, bootloader, kernel command line, initramfs, root filesystem handoff, PID 1, services, and boot troubleshooting. Linux Package and Boot Recovery Debian and Ubuntu recovery runbooks for broken packages, bad kernels, initramfs failures, GRUB rescue, emergency mode, and rollback. Network Boot and Automated Provisioning PXE, UEFI HTTP Boot, iPXE, DHCP, TFTP, automated Linux installs, Ubuntu autoinstall, cloud-init NoCloud, Kickstart, bare-metal provisioning, and troubleshooting.

caching

DNS Resolution and Caching How resolver lookup paths, caches, TTLs, negative answers, CNAME chains, and client search behavior shape DNS outcomes.

capacity

Ceph Performance and Capacity Ceph performance model, capacity planning, BlueStore, OSD latency, network design, client behavior, benchmarks, and saturation troubleshooting.

ceph

Ceph Ceph distributed storage architecture, RADOS, OSDs, monitors, managers, pools, placement groups, CRUSH, CephFS, RBD, RGW, and operations. Ceph Block, File, and Object Interfaces RBD, CephFS, and RGW mental models, command checks, snapshots, mirroring, MDS behavior, bucket gateways, and interface selection. Ceph Operations and Recovery Ceph health triage, OSD failure response, recovery and backfill, scrub repair, maintenance flags, full ratios, and safe operational runbooks. Ceph Performance and Capacity Ceph performance model, capacity planning, BlueStore, OSD latency, network design, client behavior, benchmarks, and saturation troubleshooting. Ceph RADOS, CRUSH, and Placement RADOS objects, pools, placement groups, CRUSH rules, acting sets, PG autoscaling, and placement troubleshooting. Ceph Storage Examples Practical Ceph examples for cluster health, replicated pool creation, and RBD image operations. Rook-Ceph Rook-Ceph architecture, CephCluster CRD, Kubernetes storage classes, CSI, toolbox usage, upgrades, and troubleshooting.

cephfs

Ceph Block, File, and Object Interfaces RBD, CephFS, and RGW mental models, command checks, snapshots, mirroring, MDS behavior, bucket gateways, and interface selection.

certificates

Certificates and HTTPS TLS certificates, HTTPS handshakes, chains of trust, SANs, SNI, OCSP, CA stores, and Ubuntu certificate operations.

cgroups

Containerization, OCI, and VMs Container fundamentals, OCI image/runtime/distribution standards, Linux namespaces, cgroups, overlay layers, bridge networking, macOS and Windows container behavior, KVM, hypervisors, and VM/container tradeoffs.

cicd

ML Evaluation and CI/CD ML evaluation harnesses, golden sets, regression gates, human review, release scorecards, canaries, and CI/CD for model, prompt, retrieval, and tool changes.

classical-ml

Classical ML Classical machine learning with linear models, logistic regression, trees, random forests, gradient boosting, SVMs, k-means, feature engineering, and tabular workflows.

cloud

Cloud Networking Cloud networking fundamentals for VPCs, subnets, route tables, security groups, private endpoints, peering, transit gateways, NAT, load balancers, and overlapping CIDRs. NAT Gateways and Network Address Translation Deep operational guide to NAT, NAT gateways, SNAT, DNAT, PAT, masquerade, conntrack, ephemeral ports, cloud egress, hairpin NAT, and NAT troubleshooting.

cloudnativepg

CloudNativePG How CloudNativePG runs PostgreSQL in Kubernetes, including clusters, services, failover, operator scaling, operator upgrades, backups, and operational cautions. PostgreSQL Zero-Downtime Upgrades on Kubernetes Zero-downtime and low-downtime PostgreSQL upgrade strategies on Kubernetes, including CloudNativePG rolling updates, major upgrades, logical replication cutovers, PgBouncer draining, and ordinary PostgreSQL runbooks.

cni

Kubernetes Pod Networking and CNI Kubernetes network model, Pod IPs, CNI plugins, routes, overlays, eBPF, MTU, hostNetwork, DNS path, and node-level debugging.

containers

Containerization, OCI, and VMs Container fundamentals, OCI image/runtime/distribution standards, Linux namespaces, cgroups, overlay layers, bridge networking, macOS and Windows container behavior, KVM, hypervisors, and VM/container tradeoffs. Linux Mount Namespaces and Propagation Mount namespaces, bind mounts, shared subtree propagation, chroot, pivot_root, overlay mounts, tmpfs, container mount debugging, and /proc mount views. Linux Security Controls Linux security primitives for capabilities, seccomp, AppArmor, SELinux, PAM, auditd, sudoers, file capabilities, setuid, and container boundaries. Network Namespaces and Virtual Networking Linux network namespaces, veth pairs, bridges, macvlan, ipvlan, tun/tap, VXLAN, overlays, and CNI-style packet paths.

control-loops

Core Concepts Kubernetes object model, controllers, scheduling, node agents, and reconciliation.

coredns

Kubernetes DNS and CoreDNS Kubernetes DNS names, CoreDNS, kube-dns compatibility, Pod resolv.conf, dnsPolicy, search paths, ndots, forwarding, and DNS troubleshooting.

cron

Scheduled Automation Cronjobs, anacron, systemd timers, user timers, environment pitfalls, idempotent jobs, logs, locking, and automation troubleshooting.

crush

Ceph RADOS, CRUSH, and Placement RADOS objects, pools, placement groups, CRUSH rules, acting sets, PG autoscaling, and placement troubleshooting.

csi

Kubernetes Storage and Upgrades Persistent storage, CSI, StatefulSets, volume lifecycle, and safe Kubernetes upgrade practices.

data

ML Data Pipelines and Feature Stores ML data engineering with dataset versioning, feature stores, lineage, data contracts, train/serve skew, point-in-time correctness, privacy, and reproducibility.

databases

CloudNativePG How CloudNativePG runs PostgreSQL in Kubernetes, including clusters, services, failover, operator scaling, operator upgrades, backups, and operational cautions. Database and Search Examples Practical PostgreSQL, PgBouncer, and OpenSearch examples for queries, pooling, and cluster inspection. Databases Database fundamentals, modeling, indexes, transactions, replication, and operations. OpenSearch Operations, Replication, Sharding, and HA OpenSearch operations guide covering shards, replicas, cross-cluster replication, allocation awareness, snapshots, cluster-manager failover, and HA runbooks. PgBouncer How PgBouncer works, pooling modes, sizing, HA placement, failover behavior, prepared statements, session state, observability, and operational runbooks. PostgreSQL PostgreSQL architecture, MVCC, WAL, query planning, indexes, vacuum, backups, replication, and operations. PostgreSQL Operations, HA, Replication, and Recovery Operational PostgreSQL guide covering HA managers, failover, physical and logical replication, sharding, backups, restore drills, WAL, high CPU, high RAM, and incident checks. Storage Drives, RAID, and Database Performance SSD, HDD, NVMe, RAID 0/1/5/6/10, RAID performance, disk-failure recovery, LVM RAID, and PostgreSQL and Elasticsearch storage tradeoffs.

debian

Debian and Ubuntu Operations Ubuntu-first Linux operations: apt, dpkg, systemd, journald, netplan, ufw, CA certificates, logs, services, and package troubleshooting.

debugging

Linux System Call Debugging Linux syscall debugging with strace, errno, blocking calls, file and socket syscalls, poll, epoll, futexes, and production triage boundaries.

deep-learning

Deep Learning Fundamentals Deep learning fundamentals: neural networks, layers, activations, embeddings, CNNs, RNNs, transformers, optimizers, normalization, regularization, initialization, and training stability.

deployment

MLOps Systems MLOps systems with model registries, feature stores, training pipelines, artifact versioning, reproducibility, batch and online inference, canaries, shadow evaluation, rollback, and cost governance.

device-mapper

RAID, Multipath, and Device Mapper Linux md RAID, device mapper, dm-crypt/LUKS, multipath, NVMe multipath, WWIDs, path failover, and layered storage troubleshooting.

devices

Linux Kernel Modules and Devices Linux kernel modules, built-in drivers, modprobe, module aliases, parameters, blacklists, sysfs, devtmpfs, udev, device nodes, initramfs, Secure Boot, DKMS, and troubleshooting.

dhcp

DHCP, Routers, and Switches DHCP-focused networking guide covering DORA, leases, options, default gateways, DNS options, relay agents, helper addresses, Option 82, VLANs, switches, routers, DHCP snooping, DHCPv6, and troubleshooting.

distributed-systems

Ceph Ceph distributed storage architecture, RADOS, OSDs, monitors, managers, pools, placement groups, CRUSH, CephFS, RBD, RGW, and operations.

dns

Authoritative DNS and Zones Zones, delegations, NS records, SOA serials, glue, apex constraints, wildcard behavior, and authoritative debugging. DNS Name resolution flow, DNS records, delegation, caching, negative answers, and operational debugging. DNS Examples Practical examples for DNS zones and resolver debugging. DNS Records, Responses, and Transport DNS record types, response codes, EDNS, UDP and TCP transport, truncation, reverse DNS, mail records, and operational debugging. DNS Resolution and Caching How resolver lookup paths, caches, TTLs, negative answers, CNAME chains, and client search behavior shape DNS outcomes. DNSSEC and DNS Privacy DNSSEC validation, chain of trust, DS/DNSKEY, signing failures, DNS over TLS, DNS over HTTPS, and what privacy does not solve. Domain Controllers and Directory DNS How Active Directory domain controllers depend on DNS SRV records, Kerberos, LDAP, Global Catalog, replication, and time. IPv6 Operations Operational IPv6 fundamentals: SLAAC, DHCPv6, Router Advertisements, NDP, link-local addresses, privacy addresses, dual-stack, NAT64, DNS AAAA, and firewalling. Kubernetes DNS and CoreDNS Kubernetes DNS names, CoreDNS, kube-dns compatibility, Pod resolv.conf, dnsPolicy, search paths, ndots, forwarding, and DNS troubleshooting. Kubernetes ExternalDNS How ExternalDNS watches Kubernetes resources and reconciles public or private DNS records through provider APIs. Kubernetes Networking Pod networking, Services, CoreDNS, kube-dns history, EndpointSlices, NetworkPolicy, Ingress, Gateway API, and load balancers. NATS, DNS, and Kubernetes Networking How NATS uses Kubernetes DNS, Services, StatefulSets, headless Services, route gossip, advertise addresses, NetworkPolicy, and CoreDNS during clustering and client reconnects. resolv.conf Linux resolver configuration, nameservers, search domains, ndots, timeouts, attempts, rotation, and systemd-resolved behavior.

dnssec

DNSSEC and DNS Privacy DNSSEC validation, chain of trust, DS/DNSKEY, signing failures, DNS over TLS, DNS over HTTPS, and what privacy does not solve.

ebpf

Linux eBPF and Tracing Practical Linux eBPF tracing with tracepoints, kprobes, uprobes, bpftrace, BCC, tc, XDP, and production-safe observability boundaries.

egress

Istio Gateways, Ingress, and Egress Istio ingress gateways, egress gateways, Kubernetes Gateway API, TLS termination and passthrough, SNI, external services, and gateway troubleshooting.

elasticsearch

Storage Drives, RAID, and Database Performance SSD, HDD, NVMe, RAID 0/1/5/6/10, RAID performance, disk-failure recovery, LVM RAID, and PostgreSQL and Elasticsearch storage tradeoffs.

embeddings

Retrieval-Augmented Generation RAG systems with embeddings, chunking, vector search, retrieval, reranking, context assembly, citations, freshness, and evaluation.

engines

Inference Engine Comparison Comparison guide for vLLM, TensorRT-LLM, Hugging Face TGI, llama.cpp, SGLang, Ollama, OpenAI-compatible APIs, quantization, adapters, and migration checks.

envoy

Istio Observability and Troubleshooting Istio metrics, access logs, traces, proxy sync, xDS inspection, response flags, common 503 and policy failures, and practical debugging flows. Istio Service Mesh Service mesh architecture, request paths, Envoy sidecars, ambient ztunnel and waypoint proxies, mTLS, policy, telemetry, and troubleshooting. Istio Traffic Management Istio VirtualService, DestinationRule, subsets, retries, timeouts, fault injection, traffic splits, ServiceEntry, and routing troubleshooting.

evaluation

ML 101 Foundations Beginner ML foundations: what ML is, when not to use it, datasets, features, labels, splits, training, inference, metrics, overfitting, and bias/variance. ML Alignment and Evaluation Alignment, evaluation, RLHF, preference tuning, DPO, safety policy, red teaming, regression gates, calibration, and monitoring. ML Evaluation Mastery Advanced ML evaluation with unit evals, golden sets, model-graded evals, human evals, pairwise preference evals, safety evals, regression gates, slice metrics, statistical confidence, and contamination controls. ML Evaluation and CI/CD ML evaluation harnesses, golden sets, regression gates, human review, release scorecards, canaries, and CI/CD for model, prompt, retrieval, and tool changes. ML Explainability Explainability for ML systems: interpretable models, feature attribution, saliency, counterfactuals, LIME, SHAP, attention caveats, audits, and model cards.

examples

Ceph Storage Examples Practical Ceph examples for cluster health, replicated pool creation, and RBD image operations. DNS Examples Practical examples for DNS zones and resolver debugging. Database and Search Examples Practical PostgreSQL, PgBouncer, and OpenSearch examples for queries, pooling, and cluster inspection. Identity Examples Practical OAuth, OIDC, JWKS, and JWT examples for identity troubleshooting and API validation. Istio Service Mesh Examples Practical Istio examples for VirtualService traffic splitting, DestinationRule subsets, and AuthorizationPolicy. Kubernetes Examples Practical Kubernetes examples for Deployments, Services, PodDisruptionBudgets, NetworkPolicy, and StatefulSet storage. Linux Operations Examples Practical Linux examples for systemd services, timers, rsync snapshot backups, and nftables host firewalls. Networking TLS and mTLS Examples Practical networking examples for certificate inspection and mTLS requests. Troubleshooting Examples Practical troubleshooting examples for repeatable incident capture and evidence preservation.

explainability

ML Explainability Explainability for ML systems: interpretable models, feature attribution, saliency, counterfactuals, LIME, SHAP, attention caveats, audits, and model cards.

feature-store

ML Data Pipelines and Feature Stores ML data engineering with dataset versioning, feature stores, lineage, data contracts, train/serve skew, point-in-time correctness, privacy, and reproducibility.

filesystems

Linux Filesystems and IO VFS, inodes, dentries, page cache, block devices, mounts, filesystem checks, IO schedulers, and storage troubleshooting. Linux Mounts and fstab Linux mounts, findmnt, /etc/fstab, UUIDs, systemd mount units, automounts, bind mounts, mount options, and boot-safe storage configuration. ext4, XFS, and Filesystem Repair ext4 and XFS operations, mkfs, fsck, xfs_repair, online growth, inode usage, journals, quotas, discard, and safe repair workflows.

finetuning

Advanced Fine-Tuning Advanced fine-tuning with full tuning, LoRA, QLoRA, adapter composition, multi-adapter serving, dataset mixing, long-context tuning, packing, catastrophic forgetting, and safety-preserving releases. Fine-Tuning and LoRA Fine-tuning, instruction tuning, parameter-efficient adaptation, LoRA adapters, data quality, evaluation, merge behavior, and rollback.

firewall

Firewalls, iptables, and Netfilter Linux firewall fundamentals: netfilter hooks, nftables, iptables, chains, tables, conntrack, NAT, rule ordering, logging, persistence, and troubleshooting. Routing, NAT, and Firewalls Routing tables, policy routing, NAT, connection tracking, firewall state, asymmetric paths, and load-balancer edge cases.

firewalls

Linux Operations Examples Practical Linux examples for systemd services, timers, rsync snapshot backups, and nftables host firewalls.

foundations

ML 101 Foundations Beginner ML foundations: what ML is, when not to use it, datasets, features, labels, splits, training, inference, metrics, overfitting, and bias/variance.

fundamentals

Foundational Study Review A cross-topic checklist for reviewing whether the guide covers the core mental models behind Linux, networking, DNS, Kubernetes, identity, databases, Ceph, Istio, and troubleshooting.

gateway

Istio Gateways, Ingress, and Egress Istio ingress gateways, egress gateways, Kubernetes Gateway API, TLS termination and passthrough, SNI, external services, and gateway troubleshooting.

gateway-api

Kubernetes Ingress, Gateway, and Load Balancers Ingress controllers, Gateway API, Service LoadBalancers, health checks, TLS, SNI, source IP, externalTrafficPolicy, DNS, and edge troubleshooting.

glossary

Glossary Search-focused short definitions for operational terms across Linux, networking, Kubernetes, DNS, TLS, and performance.

governance

Responsible AI and Governance Responsible AI governance with model cards, dataset cards, risk classification, human oversight, audit trails, fairness checks, red-team programs, release approval, incident response, and regulatory documentation.

gpu

Linux Linux fundamentals for developers and operators: processes, fork/exec, memory, CPU, kernel params, caches, paging, GPUs, and troubleshooting. Linux GPU Drivers Linux GPU driver stacks for AMD and NVIDIA, including kernel modules, firmware, Mesa, ROCm, CUDA, nvidia-smi, Secure Boot, containers, and troubleshooting. ML Accelerators: GPU and TPU GPU and TPU fundamentals for ML workloads: parallelism, memory, precision, batching, utilization, data movement, and troubleshooting. ML Performance Engineering ML performance engineering with training-loop profiling, GPU utilization, memory bandwidth, activation checkpointing, FlashAttention, fused kernels, distributed training bottlenecks, inference throughput tuning, and cost/performance tradeoffs.

high-availability

OpenSearch Operations, Replication, Sharding, and HA OpenSearch operations guide covering shards, replicas, cross-cluster replication, allocation awareness, snapshots, cluster-manager failover, and HA runbooks. PostgreSQL Operations, HA, Replication, and Recovery Operational PostgreSQL guide covering HA managers, failover, physical and logical replication, sharding, backups, restore drills, WAL, high CPU, high RAM, and incident checks. PostgreSQL Zero-Downtime Upgrades on Kubernetes Zero-downtime and low-downtime PostgreSQL upgrade strategies on Kubernetes, including CloudNativePG rolling updates, major upgrades, logical replication cutovers, PgBouncer draining, and ordinary PostgreSQL runbooks.

http

Forward and Reverse Proxies Forward proxies, reverse proxies, CONNECT tunnels, transparent proxies, TLS interception, proxy headers, egress control, caching, environment variables, and troubleshooting. HTTP and Proxy Debugging Practical HTTP and proxy debugging with curl, headers, redirects, keepalive, chunking, HTTP/2, gRPC, WebSockets, proxy variables, and timeout alignment. TCP, TLS, and HTTP Transport and application handshake layers: TCP state, retransmits, flow control, congestion control, TLS SNI/certificates, and HTTP behavior.

https

Certificates and HTTPS TLS certificates, HTTPS handshakes, chains of trust, SANs, SNI, OCSP, CA stores, and Ubuntu certificate operations.

identity

Domain Controllers and Directory DNS How Active Directory domain controllers depend on DNS SRV records, Kerberos, LDAP, Global Catalog, replication, and time. IdP, SAML, JWT, OAuth, and OIDC Identity provider basics, SAML assertions, OAuth 2.0 authorization, OpenID Connect authentication, JWT structure, validation checks, and troubleshooting. Identity Examples Practical OAuth, OIDC, JWKS, and JWT examples for identity troubleshooting and API validation. Identity and Access Identity-provider, federation, SSO, SAML, OAuth, OpenID Connect, JWT, token validation, and access-control study guide.

incident-response

Troubleshooting and Error Handling Cross-technology troubleshooting and error handling for Linux, networking, DNS, Kubernetes, Istio, Ceph, PostgreSQL, and distributed systems operations.

incidents

ML Observability and Incident Response ML observability, metrics, traces, prompt and retrieval logging, drift monitoring, feedback loops, and incident response runbooks.

inference

Advanced Inference and vLLM Advanced LLM inference with vLLM, PagedAttention, continuous batching, disaggregated prefill, chunked prefill, speculative decoding, prefix caching, KV-cache math, tensor and pipeline parallelism, quantized serving, LoRA serving, and autoscaling. Inference Benchmarking Benchmark methodology for LLM inference with warmup, prompt/output distributions, concurrency sweeps, TTFT, ITL, throughput, quality gates, and benchmark anti-patterns. Inference Engine Comparison Comparison guide for vLLM, TensorRT-LLM, Hugging Face TGI, llama.cpp, SGLang, Ollama, OpenAI-compatible APIs, quantization, adapters, and migration checks. Inference Runbooks Operational runbooks for LLM inference incidents: wrong output, high TTFT, slow inter-token latency, OOM, low throughput, queue buildup, cache pressure, tokenizer mismatch, and runtime regressions. LLM Inference Systems Production LLM inference systems: model files, weights, memory, inference engines, vLLM, TensorRT-LLM, TGI, llama.cpp, SGLang, Ollama, KV cache, PagedAttention, batching, quantization, routing, performance tests, and runbooks. Long-Context Serving Long-context LLM serving with RoPE scaling, sliding-window attention, sink tokens, lost-in-the-middle behavior, KV-cache growth, prompt budgeting, and long-context evals. ML Performance Engineering ML performance engineering with training-loop profiling, GPU utilization, memory bandwidth, activation checkpointing, FlashAttention, fused kernels, distributed training bottlenecks, inference throughput tuning, and cost/performance tradeoffs. ML Serving, Inference, and vLLM Production ML inference with model servers, batching, streaming, KV cache, autoscaling, canaries, inference optimization, and deep vLLM operations. MoE Inference Mixture-of-Experts inference with active vs total parameters, expert routing, expert parallelism, all-to-all communication, load balance, capacity, KV cache, and serving tradeoffs. Model Memory Math Practical LLM memory math for weights, activations, KV cache, optimizer state, model loading, quantization, model sizes, and serving capacity planning. Quantized Serving Quantized LLM serving with weight quantization, activation quantization, KV-cache quantization, GGUF, AWQ, GPTQ, FP8, quality gates, and rollout checks. Tokenizer and Chat Template Compatibility Tokenizer, chat template, special token, stop sequence, tool schema, and generation config compatibility for reliable LLM inference. vLLM Operations Operational guide for vLLM serving with scheduler concepts, PagedAttention, KV cache, prefix caching, speculative decoding, parallelism, metrics, flags, and runbooks.

infrastructure

Kubernetes Cluster architecture, reconciliation, networking, storage, and operations for modern Kubernetes. Networking Practical systems networking: OSI layers, NICs, ARP, IP routing, TCP/UDP, DNS, TLS, and packet debugging.

ingress

Istio Gateways, Ingress, and Egress Istio ingress gateways, egress gateways, Kubernetes Gateway API, TLS termination and passthrough, SNI, external services, and gateway troubleshooting. Kubernetes Ingress, Gateway, and Load Balancers Ingress controllers, Gateway API, Service LoadBalancers, health checks, TLS, SNI, source IP, externalTrafficPolicy, DNS, and edge troubleshooting. Kubernetes Networking Pod networking, Services, CoreDNS, kube-dns history, EndpointSlices, NetworkPolicy, Ingress, Gateway API, and load balancers.

interpretability

ML Explainability Explainability for ML systems: interpretable models, feature attribution, saliency, counterfactuals, LIME, SHAP, attention caveats, audits, and model cards.

io

Linux Filesystems and IO VFS, inodes, dentries, page cache, block devices, mounts, filesystem checks, IO schedulers, and storage troubleshooting.

ipc

Linux Sockets and IPC Linux sockets, TCP, UDP, Unix domain sockets, socket files, listen queues, buffers, file descriptors, pipes, signals, shared memory, and IPC troubleshooting.

ipsec

VPNs and IPsec Tunnels VPN fundamentals, IPsec tunnel mode, IKEv2, ESP, NAT-T, traffic selectors, route-based and policy-based tunnels, split tunneling, MTU, and operational troubleshooting.

iptables

Firewalls, iptables, and Netfilter Linux firewall fundamentals: netfilter hooks, nftables, iptables, chains, tables, conntrack, NAT, rule ordering, logging, persistence, and troubleshooting.

ipv6

IPv6 Operations Operational IPv6 fundamentals: SLAAC, DHCPv6, Router Advertisements, NDP, link-local addresses, privacy addresses, dual-stack, NAT64, DNS AAAA, and firewalling.

istio

Istio Istio service mesh fundamentals: control plane, data plane, sidecar mode, ambient mode, traffic management, security, observability, and operations. Istio Gateways, Ingress, and Egress Istio ingress gateways, egress gateways, Kubernetes Gateway API, TLS termination and passthrough, SNI, external services, and gateway troubleshooting. Istio Observability and Troubleshooting Istio metrics, access logs, traces, proxy sync, xDS inspection, response flags, common 503 and policy failures, and practical debugging flows. Istio Security, mTLS, and Policy Istio workload identity, mTLS, PeerAuthentication, AuthorizationPolicy, RequestAuthentication, JWT validation, trust domains, and policy debugging. Istio Service Mesh Service mesh architecture, request paths, Envoy sidecars, ambient ztunnel and waypoint proxies, mTLS, policy, telemetry, and troubleshooting. Istio Service Mesh Examples Practical Istio examples for VirtualService traffic splitting, DestinationRule subsets, and AuthorizationPolicy. Istio Traffic Management Istio VirtualService, DestinationRule, subsets, retries, timeouts, fault injection, traffic splits, ServiceEntry, and routing troubleshooting. Istio Zero Downtime Upgrades on Kubernetes Operational runbook for low-risk Istio upgrades on Kubernetes using canary control planes, revisions, revision tags, workload restarts, gateway canaries, rollback, PDBs, and validation gates.

jwt

IdP, SAML, JWT, OAuth, and OIDC Identity provider basics, SAML assertions, OAuth 2.0 authorization, OpenID Connect authentication, JWT structure, validation checks, and troubleshooting. Identity Examples Practical OAuth, OIDC, JWKS, and JWT examples for identity troubleshooting and API validation.

kernel

Linux Kernel Modules and Devices Linux kernel modules, built-in drivers, modprobe, module aliases, parameters, blacklists, sysfs, devtmpfs, udev, device nodes, initramfs, Secure Boot, DKMS, and troubleshooting.

kubernetes

CloudNativePG How CloudNativePG runs PostgreSQL in Kubernetes, including clusters, services, failover, operator scaling, operator upgrades, backups, and operational cautions. Core Concepts Kubernetes object model, controllers, scheduling, node agents, and reconciliation. Cross-Layer Incident Runbooks Operational runbooks that trace application symptoms through DNS, TCP, TLS, proxies, Linux hosts, Kubernetes Services, CNI, NAT, and cloud networking. Glossary Search-focused short definitions for operational terms across Linux, networking, Kubernetes, DNS, TLS, and performance. Incident Entry Points Symptom-first entry points for timeouts, resets, DNS works on the node but not in Pods, large payload hangs, and intermittent 5xx failures. Istio Istio service mesh fundamentals: control plane, data plane, sidecar mode, ambient mode, traffic management, security, observability, and operations. Istio Traffic Management Istio VirtualService, DestinationRule, subsets, retries, timeouts, fault injection, traffic splits, ServiceEntry, and routing troubleshooting. Istio Zero Downtime Upgrades on Kubernetes Operational runbook for low-risk Istio upgrades on Kubernetes using canary control planes, revisions, revision tags, workload restarts, gateway canaries, rollback, PDBs, and validation gates. Kubernetes Cluster architecture, reconciliation, networking, storage, and operations for modern Kubernetes. Kubernetes DNS and CoreDNS Kubernetes DNS names, CoreDNS, kube-dns compatibility, Pod resolv.conf, dnsPolicy, search paths, ndots, forwarding, and DNS troubleshooting. Kubernetes Examples Practical Kubernetes examples for Deployments, Services, PodDisruptionBudgets, NetworkPolicy, and StatefulSet storage. Kubernetes ExternalDNS How ExternalDNS watches Kubernetes resources and reconciles public or private DNS records through provider APIs. Kubernetes Ingress, Gateway, and Load Balancers Ingress controllers, Gateway API, Service LoadBalancers, health checks, TLS, SNI, source IP, externalTrafficPolicy, DNS, and edge troubleshooting. Kubernetes NetworkPolicy NetworkPolicy isolation, ingress and egress rules, podSelector, namespaceSelector, ipBlock, default deny, DNS egress, CNI enforcement, and policy debugging. Kubernetes Networking Pod networking, Services, CoreDNS, kube-dns history, EndpointSlices, NetworkPolicy, Ingress, Gateway API, and load balancers. Kubernetes Pod Networking and CNI Kubernetes network model, Pod IPs, CNI plugins, routes, overlays, eBPF, MTU, hostNetwork, DNS path, and node-level debugging. Kubernetes Services and EndpointSlices Service types, selectors, ClusterIP, NodePort, LoadBalancer, headless Services, EndpointSlices, kube-proxy, readiness, and service debugging. Kubernetes Storage and Upgrades Persistent storage, CSI, StatefulSets, volume lifecycle, and safe Kubernetes upgrade practices. NATS, DNS, and Kubernetes Networking How NATS uses Kubernetes DNS, Services, StatefulSets, headless Services, route gossip, advertise addresses, NetworkPolicy, and CoreDNS during clustering and client reconnects. Network Namespaces and Virtual Networking Linux network namespaces, veth pairs, bridges, macvlan, ipvlan, tun/tap, VXLAN, overlays, and CNI-style packet paths. PostgreSQL Zero-Downtime Upgrades on Kubernetes Zero-downtime and low-downtime PostgreSQL upgrade strategies on Kubernetes, including CloudNativePG rolling updates, major upgrades, logical replication cutovers, PgBouncer draining, and ordinary PostgreSQL runbooks. Request Path A master walkthrough of one request through DNS, client behavior, TCP, TLS, proxies, Kubernetes Service routing, CNI, Pod, application, database, and the response path. Rook-Ceph Rook-Ceph architecture, CephCluster CRD, Kubernetes storage classes, CSI, toolbox usage, upgrades, and troubleshooting. Troubleshooting First checks and failure paths for common Kubernetes incidents.

linux

Containerization, OCI, and VMs Container fundamentals, OCI image/runtime/distribution standards, Linux namespaces, cgroups, overlay layers, bridge networking, macOS and Windows container behavior, KVM, hypervisors, and VM/container tradeoffs. Cross-Layer Incident Runbooks Operational runbooks that trace application symptoms through DNS, TCP, TLS, proxies, Linux hosts, Kubernetes Services, CNI, NAT, and cloud networking. Cross-Topic Study Paths Cross-topic paths for debugging a 504, Pod networking, Linux performance, TLS and mTLS, and cloud egress. Debian and Ubuntu Operations Ubuntu-first Linux operations: apt, dpkg, systemd, journald, netplan, ufw, CA certificates, logs, services, and package troubleshooting. Glossary Search-focused short definitions for operational terms across Linux, networking, Kubernetes, DNS, TLS, and performance. Incident Entry Points Symptom-first entry points for timeouts, resets, DNS works on the node but not in Pods, large payload hangs, and intermittent 5xx failures. Linux Linux fundamentals for developers and operators: processes, fork/exec, memory, CPU, kernel params, caches, paging, GPUs, and troubleshooting. Linux Backup and File Transfer Linux backup and transfer notes covering rsync, scp, snapshot backups, consistency, restore testing, exclusions, permissions, and automation. Linux Block Devices and Partitioning Linux block devices, NVMe and SCSI naming, partitions, GPT, UUIDs, labels, udev, stable device paths, and safe disk identification. Linux Boot and Userspace Firmware, bootloader, kernel command line, initramfs, root filesystem handoff, PID 1, services, and boot troubleshooting. Linux Filesystems and IO VFS, inodes, dentries, page cache, block devices, mounts, filesystem checks, IO schedulers, and storage troubleshooting. Linux GPU Drivers Linux GPU driver stacks for AMD and NVIDIA, including kernel modules, firmware, Mesa, ROCm, CUDA, nvidia-smi, Secure Boot, containers, and troubleshooting. Linux Kernel Modules and Devices Linux kernel modules, built-in drivers, modprobe, module aliases, parameters, blacklists, sysfs, devtmpfs, udev, device nodes, initramfs, Secure Boot, DKMS, and troubleshooting. Linux Kernel Network Performance Linux kernel packet processing, NAPI, softirq, NIC queues, RPS, RFS, XPS, offloads, qdisc, drops, and practical network performance troubleshooting. Linux LVM Logical Volume Manager fundamentals, advanced operations, resizing, thin provisioning, snapshots, migration, and troubleshooting. Linux Memory Pressure and OOM Linux memory troubleshooting for RSS, VSZ, page cache, slab, THP, NUMA, swap, cgroup memory, PSI, and OOM killer behavior. Linux Mount Namespaces and Propagation Mount namespaces, bind mounts, shared subtree propagation, chroot, pivot_root, overlay mounts, tmpfs, container mount debugging, and /proc mount views. Linux Mounts and fstab Linux mounts, findmnt, /etc/fstab, UUIDs, systemd mount units, automounts, bind mounts, mount options, and boot-safe storage configuration. Linux Network Stack Linux sockets, routes, neighbor tables, netfilter, conntrack, qdisc, NIC queues, namespaces, and network troubleshooting. Linux Operations Examples Practical Linux examples for systemd services, timers, rsync snapshot backups, and nftables host firewalls. Linux Package and Boot Recovery Debian and Ubuntu recovery runbooks for broken packages, bad kernels, initramfs failures, GRUB rescue, emergency mode, and rollback. Linux Performance Triage Runbooks Symptom-driven Linux runbooks for high CPU, high load, memory pressure, disk latency, softirq saturation, file descriptor exhaustion, and cgroup throttling. Linux Processes and Threads Linux processes, threads, tasks, PIDs, TIDs, fork, exec, wait, zombies, signals, scheduling, cgroups, namespaces, and process troubleshooting. Linux Security Controls Linux security primitives for capabilities, seccomp, AppArmor, SELinux, PAM, auditd, sudoers, file capabilities, setuid, and container boundaries. Linux Sockets and IPC Linux sockets, TCP, UDP, Unix domain sockets, socket files, listen queues, buffers, file descriptors, pipes, signals, shared memory, and IPC troubleshooting. Linux Storage Health and Performance Linux storage observability, iostat, SMART, NVMe health, kernel I/O errors, discard, queue depth, latency, saturation, and failure response. Linux System Call Debugging Linux syscall debugging with strace, errno, blocking calls, file and socket syscalls, poll, epoll, futexes, and production triage boundaries. Linux TCP Kernel Tuning Linux TCP listen queues, SYN backlog, socket buffers, ephemeral ports, TIME_WAIT, keepalives, conntrack pressure, and safe sysctl tuning. Linux eBPF and Tracing Practical Linux eBPF tracing with tracepoints, kprobes, uprobes, bpftrace, BCC, tc, XDP, and production-safe observability boundaries. Logs and Observability Linux logs, journald, syslog, dmesg, service status, boot logs, log rotation, metrics, and incident evidence collection. Network Boot and Automated Provisioning PXE, UEFI HTTP Boot, iPXE, DHCP, TFTP, automated Linux installs, Ubuntu autoinstall, cloud-init NoCloud, Kickstart, bare-metal provisioning, and troubleshooting. Network Namespaces and Virtual Networking Linux network namespaces, veth pairs, bridges, macvlan, ipvlan, tun/tap, VXLAN, overlays, and CNI-style packet paths. Packet Path How packets move through local sockets, routing, neighbor lookup, firewalls, conntrack, qdisc, NIC queues, and return paths. RAID, Multipath, and Device Mapper Linux md RAID, device mapper, dm-crypt/LUKS, multipath, NVMe multipath, WWIDs, path failover, and layered storage troubleshooting. Request Path A master walkthrough of one request through DNS, client behavior, TCP, TLS, proxies, Kubernetes Service routing, CNI, Pod, application, database, and the response path. SSH Access OpenSSH server administration on Ubuntu: sshd config, keys, authentication, host keys, logs, access control, and troubleshooting. Scheduled Automation Cronjobs, anacron, systemd timers, user timers, environment pitfalls, idempotent jobs, logs, locking, and automation troubleshooting. Storage Drives, RAID, and Database Performance SSD, HDD, NVMe, RAID 0/1/5/6/10, RAID performance, disk-failure recovery, LVM RAID, and PostgreSQL and Elasticsearch storage tradeoffs. Switching, VLANs, and Hosts Layer 2 switching, MAC tables, VLAN access and trunk ports, Linux bridges, 802.1Q tagging, and /etc/hosts name overrides. TCP and Sockets TCP state, sockets, listen queues, receive/send buffers, TIME_WAIT, retransmits, keepalive, ephemeral ports, and Linux observability. Time, Hostname, and Identity Time synchronization, timezone, hostname, machine-id, DNS identity, certificates, logs, Kerberos sensitivity, and Ubuntu host identity operations. Users, Permissions, and sudo Linux identities, groups, file modes, ownership, sudo, service users, locked accounts, ACLs, and permission troubleshooting on Ubuntu. Zero-Trust Networking Network security patterns that combine host firewall policy, nftables, mTLS, certificate rotation, SNI, ALPN, service identity, SSH hardening, auditd, SELinux, AppArmor, and real traffic debugging. ext4, XFS, and Filesystem Repair ext4 and XFS operations, mkfs, fsck, xfs_repair, online growth, inode usage, journals, quotas, discard, and safe repair workflows. resolv.conf Linux resolver configuration, nameservers, search domains, ndots, timeouts, attempts, rotation, and systemd-resolved behavior. systemd systemd units, services, targets, dependencies, timers, journals, cgroups, resource controls, and troubleshooting. systemd Networking systemd-networkd, systemd-resolved, .network, .netdev, .link files, network targets, wait-online behavior, and operational troubleshooting. systemd Socket Activation and Network Services systemd socket activation, ListenStream, ListenDatagram, Accept modes, service dependencies, restart behavior, resource controls, and network sandboxing.

llm

LLM Inference Systems Production LLM inference systems: model files, weights, memory, inference engines, vLLM, TensorRT-LLM, TGI, llama.cpp, SGLang, Ollama, KV cache, PagedAttention, batching, quantization, routing, performance tests, and runbooks. LLM Training Lifecycle LLM lifecycle from pretraining and continued pretraining to SFT, RLHF, DPO, RLAIF, preference data, synthetic data, data filtering, and stage-specific evaluation. ML Prompt Operations Prompt engineering operations with templates, versioning, structured outputs, injection resistance, system/developer/user boundaries, evals, and rollback. Transformer Internals Transformer internals covering tokenization, embeddings, positional encodings, RoPE, self-attention, multi-head attention, MLP blocks, LayerNorm/RMSNorm, decoder-only models, KV cache, context windows, and MoE basics.

load-balancing

Load Balancers and Proxies L4 and L7 load balancing, reverse proxies, health checks, TLS termination, source IP preservation, PROXY protocol, headers, and timeout failures.

logs

Logs and Observability Linux logs, journald, syslog, dmesg, service status, boot logs, log rotation, metrics, and incident evidence collection.

long-context

Long-Context Serving Long-context LLM serving with RoPE scaling, sliding-window attention, sink tokens, lost-in-the-middle behavior, KV-cache growth, prompt budgeting, and long-context evals.

lora

Advanced Fine-Tuning Advanced fine-tuning with full tuning, LoRA, QLoRA, adapter composition, multi-adapter serving, dataset mixing, long-context tuning, packing, catastrophic forgetting, and safety-preserving releases. Fine-Tuning and LoRA Fine-tuning, instruction tuning, parameter-efficient adaptation, LoRA adapters, data quality, evaluation, merge behavior, and rollback.

lvm

Linux LVM Logical Volume Manager fundamentals, advanced operations, resizing, thin provisioning, snapshots, migration, and troubleshooting.

machine-learning

Advanced Agents Advanced agent engineering with ReAct, planning, reflection, tool routing, multi-agent systems, durable execution, memory, sandboxing, approval workflows, trajectory evaluation, and failure recovery. Advanced Fine-Tuning Advanced fine-tuning with full tuning, LoRA, QLoRA, adapter composition, multi-adapter serving, dataset mixing, long-context tuning, packing, catastrophic forgetting, and safety-preserving releases. Advanced Inference and vLLM Advanced LLM inference with vLLM, PagedAttention, continuous batching, disaggregated prefill, chunked prefill, speculative decoding, prefix caching, KV-cache math, tensor and pipeline parallelism, quantized serving, LoRA serving, and autoscaling. Advanced ML Architectures Advanced model architectures including Mixture of Experts, retrieval-augmented models, state space models, diffusion transformers, sparse attention, long-context architectures, and encoder-only, decoder-only, and encoder-decoder tradeoffs. Advanced ML Observability Advanced ML observability with drift detection, data quality monitoring, online evals, human feedback loops, trace schemas, prompt/retrieval/model/tool observability, safety monitoring, cost monitoring, and incident review templates. Advanced RAG Advanced retrieval-augmented generation with hybrid retrieval, query planning, multi-hop retrieval, reranker architectures, GraphRAG, context compression, citation verification, agentic RAG, retrieval evals, and RAG security. Classical ML Classical machine learning with linear models, logistic regression, trees, random forests, gradient boosting, SVMs, k-means, feature engineering, and tabular workflows. Deep Learning Fundamentals Deep learning fundamentals: neural networks, layers, activations, embeddings, CNNs, RNNs, transformers, optimizers, normalization, regularization, initialization, and training stability. Fine-Tuning and LoRA Fine-tuning, instruction tuning, parameter-efficient adaptation, LoRA adapters, data quality, evaluation, merge behavior, and rollback. Inference Benchmarking Benchmark methodology for LLM inference with warmup, prompt/output distributions, concurrency sweeps, TTFT, ITL, throughput, quality gates, and benchmark anti-patterns. Inference Engine Comparison Comparison guide for vLLM, TensorRT-LLM, Hugging Face TGI, llama.cpp, SGLang, Ollama, OpenAI-compatible APIs, quantization, adapters, and migration checks. Inference Runbooks Operational runbooks for LLM inference incidents: wrong output, high TTFT, slow inter-token latency, OOM, low throughput, queue buildup, cache pressure, tokenizer mismatch, and runtime regressions. LLM Inference Systems Production LLM inference systems: model files, weights, memory, inference engines, vLLM, TensorRT-LLM, TGI, llama.cpp, SGLang, Ollama, KV cache, PagedAttention, batching, quantization, routing, performance tests, and runbooks. LLM Training Lifecycle LLM lifecycle from pretraining and continued pretraining to SFT, RLHF, DPO, RLAIF, preference data, synthetic data, data filtering, and stage-specific evaluation. Long-Context Serving Long-context LLM serving with RoPE scaling, sliding-window attention, sink tokens, lost-in-the-middle behavior, KV-cache growth, prompt budgeting, and long-context evals. ML 101 Foundations Beginner ML foundations: what ML is, when not to use it, datasets, features, labels, splits, training, inference, metrics, overfitting, and bias/variance. ML Accelerators: GPU and TPU GPU and TPU fundamentals for ML workloads: parallelism, memory, precision, batching, utilization, data movement, and troubleshooting. ML Agents and Tool Use Agentic ML systems with planning loops, tools, state, memory, idempotency, guardrails, human approval, and evaluation. ML Alignment and Evaluation Alignment, evaluation, RLHF, preference tuning, DPO, safety policy, red teaming, regression gates, calibration, and monitoring. ML Data Pipelines and Feature Stores ML data engineering with dataset versioning, feature stores, lineage, data contracts, train/serve skew, point-in-time correctness, privacy, and reproducibility. ML Evaluation Mastery Advanced ML evaluation with unit evals, golden sets, model-graded evals, human evals, pairwise preference evals, safety evals, regression gates, slice metrics, statistical confidence, and contamination controls. ML Evaluation and CI/CD ML evaluation harnesses, golden sets, regression gates, human review, release scorecards, canaries, and CI/CD for model, prompt, retrieval, and tool changes. ML Explainability Explainability for ML systems: interpretable models, feature attribution, saliency, counterfactuals, LIME, SHAP, attention caveats, audits, and model cards. ML Models, Types, and Weights Model families, model types, parameters, weights, checkpoints, tokenizers, embeddings, transformers, diffusion models, and inference boundaries. ML Observability and Incident Response ML observability, metrics, traces, prompt and retrieval logging, drift monitoring, feedback loops, and incident response runbooks. ML Performance Engineering ML performance engineering with training-loop profiling, GPU utilization, memory bandwidth, activation checkpointing, FlashAttention, fused kernels, distributed training bottlenecks, inference throughput tuning, and cost/performance tradeoffs. ML Prompt Operations Prompt engineering operations with templates, versioning, structured outputs, injection resistance, system/developer/user boundaries, evals, and rollback. ML Security Threats Advanced ML security threats: prompt injection, jailbreaks, data poisoning, model extraction, membership inference, training data leakage, secrets in prompts, supply chain risk, tenant isolation, and secure RAG. ML Security and Privacy ML security and privacy risks including prompt injection, data exfiltration, model supply chain, poisoned retrieval, tenant isolation, PII, retention, and audit logging. ML Serving, Inference, and vLLM Production ML inference with model servers, batching, streaming, KV cache, autoscaling, canaries, inference optimization, and deep vLLM operations. MLOps Systems MLOps systems with model registries, feature stores, training pipelines, artifact versioning, reproducibility, batch and online inference, canaries, shadow evaluation, rollback, and cost governance. Machine Learning Machine learning systems study guide from ML 101 through advanced concepts: math, classical ML, deep learning, transformers, LLM training, fine-tuning, RAG, agents, serving, vLLM, MLOps, security, evaluation, performance, and governance. Math for ML Practical math for machine learning: vectors, matrices, tensors, dot products, cosine similarity, gradients, softmax, cross entropy, KL divergence, probability, and attention intuition. MoE Inference Mixture-of-Experts inference with active vs total parameters, expert routing, expert parallelism, all-to-all communication, load balance, capacity, KV cache, and serving tradeoffs. Model Memory Math Practical LLM memory math for weights, activations, KV cache, optimizer state, model loading, quantization, model sizes, and serving capacity planning. Multimodal ML Multimodal ML with vision, audio, speech-to-text, text-to-speech, vision-language models, image embeddings, OCR pipelines, multimodal RAG, and video model basics. PyTorch Fundamentals PyTorch fundamentals for tensors, modules, autograd, losses, optimizers, dataloaders, training loops, mixed precision, and checkpointing. Quantized Serving Quantized LLM serving with weight quantization, activation quantization, KV-cache quantization, GGUF, AWQ, GPTQ, FP8, quality gates, and rollout checks. Responsible AI and Governance Responsible AI governance with model cards, dataset cards, risk classification, human oversight, audit trails, fairness checks, red-team programs, release approval, incident response, and regulatory documentation. Retrieval-Augmented Generation RAG systems with embeddings, chunking, vector search, retrieval, reranking, context assembly, citations, freshness, and evaluation. Tokenizer and Chat Template Compatibility Tokenizer, chat template, special token, stop sequence, tool schema, and generation config compatibility for reliable LLM inference. Transformer Internals Transformer internals covering tokenization, embeddings, positional encodings, RoPE, self-attention, multi-head attention, MLP blocks, LayerNorm/RMSNorm, decoder-only models, KV cache, context windows, and MoE basics. vLLM Operations Operational guide for vLLM serving with scheduler concepts, PagedAttention, KV cache, prefix caching, speculative decoding, parallelism, metrics, flags, and runbooks.

math

Math for ML Practical math for machine learning: vectors, matrices, tensors, dot products, cosine similarity, gradients, softmax, cross entropy, KL divergence, probability, and attention intuition.

memory

Linux Memory Pressure and OOM Linux memory troubleshooting for RSS, VSZ, page cache, slab, THP, NUMA, swap, cgroup memory, PSI, and OOM killer behavior. Model Memory Math Practical LLM memory math for weights, activations, KV cache, optimizer state, model loading, quantization, model sizes, and serving capacity planning.

ml-101

ML 101 Foundations Beginner ML foundations: what ML is, when not to use it, datasets, features, labels, splits, training, inference, metrics, overfitting, and bias/variance.

mlops

MLOps Systems MLOps systems with model registries, feature stores, training pipelines, artifact versioning, reproducibility, batch and online inference, canaries, shadow evaluation, rollback, and cost governance.

models

ML Models, Types, and Weights Model families, model types, parameters, weights, checkpoints, tokenizers, embeddings, transformers, diffusion models, and inference boundaries. Machine Learning Machine learning systems study guide from ML 101 through advanced concepts: math, classical ML, deep learning, transformers, LLM training, fine-tuning, RAG, agents, serving, vLLM, MLOps, security, evaluation, performance, and governance.

moe

MoE Inference Mixture-of-Experts inference with active vs total parameters, expert routing, expert parallelism, all-to-all communication, load balance, capacity, KV cache, and serving tradeoffs.

monitoring

Advanced ML Observability Advanced ML observability with drift detection, data quality monitoring, online evals, human feedback loops, trace schemas, prompt/retrieval/model/tool observability, safety monitoring, cost monitoring, and incident review templates. ML Observability and Incident Response ML observability, metrics, traces, prompt and retrieval logging, drift monitoring, feedback loops, and incident response runbooks.

mounts

Linux Mount Namespaces and Propagation Mount namespaces, bind mounts, shared subtree propagation, chroot, pivot_root, overlay mounts, tmpfs, container mount debugging, and /proc mount views.

mtls

Istio Security, mTLS, and Policy Istio workload identity, mTLS, PeerAuthentication, AuthorizationPolicy, RequestAuthentication, JWT validation, trust domains, and policy debugging. Istio Service Mesh Service mesh architecture, request paths, Envoy sidecars, ambient ztunnel and waypoint proxies, mTLS, policy, telemetry, and troubleshooting. Networking TLS and mTLS Examples Practical networking examples for certificate inspection and mTLS requests.

mtu

ICMP, MTU, and Path Testing ICMP, ping, traceroute, path MTU discovery, fragmentation, tunnel overhead, packet loss, jitter, and practical path testing.

multimodal

Multimodal ML Multimodal ML with vision, audio, speech-to-text, text-to-speech, vision-language models, image embeddings, OCR pipelines, multimodal RAG, and video model basics.

namespaces

Containerization, OCI, and VMs Container fundamentals, OCI image/runtime/distribution standards, Linux namespaces, cgroups, overlay layers, bridge networking, macOS and Windows container behavior, KVM, hypervisors, and VM/container tradeoffs. Linux Mount Namespaces and Propagation Mount namespaces, bind mounts, shared subtree propagation, chroot, pivot_root, overlay mounts, tmpfs, container mount debugging, and /proc mount views.

nat

Cloud Networking Cloud networking fundamentals for VPCs, subnets, route tables, security groups, private endpoints, peering, transit gateways, NAT, load balancers, and overlapping CIDRs. NAT Gateways and Network Address Translation Deep operational guide to NAT, NAT gateways, SNAT, DNAT, PAT, masquerade, conntrack, ephemeral ports, cloud egress, hairpin NAT, and NAT troubleshooting. Routing, NAT, and Firewalls Routing tables, policy routing, NAT, connection tracking, firewall state, asymmetric paths, and load-balancer edge cases.

nats

NATS, DNS, and Kubernetes Networking How NATS uses Kubernetes DNS, Services, StatefulSets, headless Services, route gossip, advertise addresses, NetworkPolicy, and CoreDNS during clustering and client reconnects.

networking

BGP and Dynamic Routing BGP fundamentals for operators: ASNs, peering, route advertisement, route selection, communities, ECMP, anycast, and failure modes. Certificates and HTTPS TLS certificates, HTTPS handshakes, chains of trust, SANs, SNI, OCSP, CA stores, and Ubuntu certificate operations. Cloud Networking Cloud networking fundamentals for VPCs, subnets, route tables, security groups, private endpoints, peering, transit gateways, NAT, load balancers, and overlapping CIDRs. Cross-Layer Incident Runbooks Operational runbooks that trace application symptoms through DNS, TCP, TLS, proxies, Linux hosts, Kubernetes Services, CNI, NAT, and cloud networking. Cross-Topic Study Paths Cross-topic paths for debugging a 504, Pod networking, Linux performance, TLS and mTLS, and cloud egress. DHCP, Routers, and Switches DHCP-focused networking guide covering DORA, leases, options, default gateways, DNS options, relay agents, helper addresses, Option 82, VLANs, switches, routers, DHCP snooping, DHCPv6, and troubleshooting. DNS Name resolution flow, DNS records, delegation, caching, negative answers, and operational debugging. Datacenter L2/L3 Operations Datacenter switching and routing concepts for host operators: LACP, MLAG, STP, ARP/NDP instability, EVPN/VXLAN, ECMP, anycast, route dampening, and fabric incident evidence. Domain Controllers and Directory DNS How Active Directory domain controllers depend on DNS SRV records, Kerberos, LDAP, Global Catalog, replication, and time. Firewalls, iptables, and Netfilter Linux firewall fundamentals: netfilter hooks, nftables, iptables, chains, tables, conntrack, NAT, rule ordering, logging, persistence, and troubleshooting. Forward and Reverse Proxies Forward proxies, reverse proxies, CONNECT tunnels, transparent proxies, TLS interception, proxy headers, egress control, caching, environment variables, and troubleshooting. Glossary Search-focused short definitions for operational terms across Linux, networking, Kubernetes, DNS, TLS, and performance. HTTP and Proxy Debugging Practical HTTP and proxy debugging with curl, headers, redirects, keepalive, chunking, HTTP/2, gRPC, WebSockets, proxy variables, and timeout alignment. ICMP, MTU, and Path Testing ICMP, ping, traceroute, path MTU discovery, fragmentation, tunnel overhead, packet loss, jitter, and practical path testing. IP Addressing and Subnetting IPv4 and IPv6 addressing, CIDR, subnets, default gateways, private address space, source selection, and route troubleshooting. IPv6 Operations Operational IPv6 fundamentals: SLAAC, DHCPv6, Router Advertisements, NDP, link-local addresses, privacy addresses, dual-stack, NAT64, DNS AAAA, and firewalling. Incident Entry Points Symptom-first entry points for timeouts, resets, DNS works on the node but not in Pods, large payload hangs, and intermittent 5xx failures. Istio Istio service mesh fundamentals: control plane, data plane, sidecar mode, ambient mode, traffic management, security, observability, and operations. Kubernetes ExternalDNS How ExternalDNS watches Kubernetes resources and reconciles public or private DNS records through provider APIs. Kubernetes Ingress, Gateway, and Load Balancers Ingress controllers, Gateway API, Service LoadBalancers, health checks, TLS, SNI, source IP, externalTrafficPolicy, DNS, and edge troubleshooting. Kubernetes NetworkPolicy NetworkPolicy isolation, ingress and egress rules, podSelector, namespaceSelector, ipBlock, default deny, DNS egress, CNI enforcement, and policy debugging. Kubernetes Networking Pod networking, Services, CoreDNS, kube-dns history, EndpointSlices, NetworkPolicy, Ingress, Gateway API, and load balancers. Kubernetes Pod Networking and CNI Kubernetes network model, Pod IPs, CNI plugins, routes, overlays, eBPF, MTU, hostNetwork, DNS path, and node-level debugging. Kubernetes Services and EndpointSlices Service types, selectors, ClusterIP, NodePort, LoadBalancer, headless Services, EndpointSlices, kube-proxy, readiness, and service debugging. Linux Kernel Network Performance Linux kernel packet processing, NAPI, softirq, NIC queues, RPS, RFS, XPS, offloads, qdisc, drops, and practical network performance troubleshooting. Linux Network Stack Linux sockets, routes, neighbor tables, netfilter, conntrack, qdisc, NIC queues, namespaces, and network troubleshooting. Linux TCP Kernel Tuning Linux TCP listen queues, SYN backlog, socket buffers, ephemeral ports, TIME_WAIT, keepalives, conntrack pressure, and safe sysctl tuning. Load Balancers and Proxies L4 and L7 load balancing, reverse proxies, health checks, TLS termination, source IP preservation, PROXY protocol, headers, and timeout failures. NAT Gateways and Network Address Translation Deep operational guide to NAT, NAT gateways, SNAT, DNAT, PAT, masquerade, conntrack, ephemeral ports, cloud egress, hairpin NAT, and NAT troubleshooting. NATS, DNS, and Kubernetes Networking How NATS uses Kubernetes DNS, Services, StatefulSets, headless Services, route gossip, advertise addresses, NetworkPolicy, and CoreDNS during clustering and client reconnects. Network Boot and Automated Provisioning PXE, UEFI HTTP Boot, iPXE, DHCP, TFTP, automated Linux installs, Ubuntu autoinstall, cloud-init NoCloud, Kickstart, bare-metal provisioning, and troubleshooting. Network Namespaces and Virtual Networking Linux network namespaces, veth pairs, bridges, macvlan, ipvlan, tun/tap, VXLAN, overlays, and CNI-style packet paths. Networking Practical systems networking: OSI layers, NICs, ARP, IP routing, TCP/UDP, DNS, TLS, and packet debugging. Networking TLS and mTLS Examples Practical networking examples for certificate inspection and mTLS requests. Packet Capture and Analysis Practical tcpdump and Wireshark packet analysis for filters, handshakes, retransmits, resets, DNS, TLS SNI, VLAN tags, MTU, and rolling captures. Packet Path How packets move through local sockets, routing, neighbor lookup, firewalls, conntrack, qdisc, NIC queues, and return paths. PgBouncer How PgBouncer works, pooling modes, sizing, HA placement, failover behavior, prepared statements, session state, observability, and operational runbooks. Request Path A master walkthrough of one request through DNS, client behavior, TCP, TLS, proxies, Kubernetes Service routing, CNI, Pod, application, database, and the response path. Resilience, Timeouts, and Draining Practical network resilience patterns: timeout budgets, retries, backoff, connection pooling, keepalive, idle timeouts, load balancer draining, rolling restarts, DNS TTLs, and zero-downtime deploy behavior. Routing, NAT, and Firewalls Routing tables, policy routing, NAT, connection tracking, firewall state, asymmetric paths, and load-balancer edge cases. Switching, VLANs, and Hosts Layer 2 switching, MAC tables, VLAN access and trunk ports, Linux bridges, 802.1Q tagging, and /etc/hosts name overrides. TCP and Sockets TCP state, sockets, listen queues, receive/send buffers, TIME_WAIT, retransmits, keepalive, ephemeral ports, and Linux observability. TCP, TLS, and HTTP Transport and application handshake layers: TCP state, retransmits, flow control, congestion control, TLS SNI/certificates, and HTTP behavior. UDP, QUIC, and Connectionless Traffic UDP behavior, DNS and DHCP traffic, QUIC, connection tracking, timeouts, packet loss, retries, and operational debugging. VPNs and IPsec Tunnels VPN fundamentals, IPsec tunnel mode, IKEv2, ESP, NAT-T, traffic selectors, route-based and policy-based tunnels, split tunneling, MTU, and operational troubleshooting. Zero-Trust Networking Network security patterns that combine host firewall policy, nftables, mTLS, certificate rotation, SNI, ALPN, service identity, SSH hardening, auditd, SELinux, AppArmor, and real traffic debugging. systemd Networking systemd-networkd, systemd-resolved, .network, .netdev, .link files, network targets, wait-online behavior, and operational troubleshooting. systemd Socket Activation and Network Services systemd socket activation, ListenStream, ListenDatagram, Accept modes, service dependencies, restart behavior, resource controls, and network sandboxing.

networkpolicy

Kubernetes Examples Practical Kubernetes examples for Deployments, Services, PodDisruptionBudgets, NetworkPolicy, and StatefulSet storage.

neural-networks

Deep Learning Fundamentals Deep learning fundamentals: neural networks, layers, activations, embeddings, CNNs, RNNs, transformers, optimizers, normalization, regularization, initialization, and training stability.

nvidia

Linux GPU Drivers Linux GPU driver stacks for AMD and NVIDIA, including kernel modules, firmware, Mesa, ROCm, CUDA, nvidia-smi, Secure Boot, containers, and troubleshooting.

oauth

IdP, SAML, JWT, OAuth, and OIDC Identity provider basics, SAML assertions, OAuth 2.0 authorization, OpenID Connect authentication, JWT structure, validation checks, and troubleshooting. Identity Examples Practical OAuth, OIDC, JWKS, and JWT examples for identity troubleshooting and API validation.

observability

Advanced ML Observability Advanced ML observability with drift detection, data quality monitoring, online evals, human feedback loops, trace schemas, prompt/retrieval/model/tool observability, safety monitoring, cost monitoring, and incident review templates. Istio Observability and Troubleshooting Istio metrics, access logs, traces, proxy sync, xDS inspection, response flags, common 503 and policy failures, and practical debugging flows. Linux eBPF and Tracing Practical Linux eBPF tracing with tracepoints, kprobes, uprobes, bpftrace, BCC, tc, XDP, and production-safe observability boundaries. Logs and Observability Linux logs, journald, syslog, dmesg, service status, boot logs, log rotation, metrics, and incident evidence collection. ML Observability and Incident Response ML observability, metrics, traces, prompt and retrieval logging, drift monitoring, feedback loops, and incident response runbooks.

oci

Containerization, OCI, and VMs Container fundamentals, OCI image/runtime/distribution standards, Linux namespaces, cgroups, overlay layers, bridge networking, macOS and Windows container behavior, KVM, hypervisors, and VM/container tradeoffs.

oidc

IdP, SAML, JWT, OAuth, and OIDC Identity provider basics, SAML assertions, OAuth 2.0 authorization, OpenID Connect authentication, JWT structure, validation checks, and troubleshooting. Identity Examples Practical OAuth, OIDC, JWKS, and JWT examples for identity troubleshooting and API validation.

oom

Linux Memory Pressure and OOM Linux memory troubleshooting for RSS, VSZ, page cache, slab, THP, NUMA, swap, cgroup memory, PSI, and OOM killer behavior.

opensearch

Database and Search Examples Practical PostgreSQL, PgBouncer, and OpenSearch examples for queries, pooling, and cluster inspection. OpenSearch Operations, Replication, Sharding, and HA OpenSearch operations guide covering shards, replicas, cross-cluster replication, allocation awareness, snapshots, cluster-manager failover, and HA runbooks.

operating-systems

Linux Linux fundamentals for developers and operators: processes, fork/exec, memory, CPU, kernel params, caches, paging, GPUs, and troubleshooting.

operations

Ceph Operations and Recovery Ceph health triage, OSD failure response, recovery and backfill, scrub repair, maintenance flags, full ratios, and safe operational runbooks. DNS Records, Responses, and Transport DNS record types, response codes, EDNS, UDP and TCP transport, truncation, reverse DNS, mail records, and operational debugging. Databases Database fundamentals, modeling, indexes, transactions, replication, and operations. Debian and Ubuntu Operations Ubuntu-first Linux operations: apt, dpkg, systemd, journald, netplan, ufw, CA certificates, logs, services, and package troubleshooting. Foundational Study Review A cross-topic checklist for reviewing whether the guide covers the core mental models behind Linux, networking, DNS, Kubernetes, identity, databases, Ceph, Istio, and troubleshooting. Inference Runbooks Operational runbooks for LLM inference incidents: wrong output, high TTFT, slow inter-token latency, OOM, low throughput, queue buildup, cache pressure, tokenizer mismatch, and runtime regressions. Istio Zero Downtime Upgrades on Kubernetes Operational runbook for low-risk Istio upgrades on Kubernetes using canary control planes, revisions, revision tags, workload restarts, gateway canaries, rollback, PDBs, and validation gates. ML Prompt Operations Prompt engineering operations with templates, versioning, structured outputs, injection resistance, system/developer/user boundaries, evals, and rollback. Machine Learning Machine learning systems study guide from ML 101 through advanced concepts: math, classical ML, deep learning, transformers, LLM training, fine-tuning, RAG, agents, serving, vLLM, MLOps, security, evaluation, performance, and governance. Troubleshooting First checks and failure paths for common Kubernetes incidents. Troubleshooting Examples Practical troubleshooting examples for repeatable incident capture and evidence preservation. Troubleshooting and Error Handling Cross-technology troubleshooting and error handling for Linux, networking, DNS, Kubernetes, Istio, Ceph, PostgreSQL, and distributed systems operations. vLLM Operations Operational guide for vLLM serving with scheduler concepts, PagedAttention, KV cache, prefix caching, speculative decoding, parallelism, metrics, flags, and runbooks.

optimization

Math for ML Practical math for machine learning: vectors, matrices, tensors, dot products, cosine similarity, gradients, softmax, cross entropy, KL divergence, probability, and attention intuition.

orchestration

Kubernetes Cluster architecture, reconciliation, networking, storage, and operations for modern Kubernetes.

packet-analysis

Packet Capture and Analysis Practical tcpdump and Wireshark packet analysis for filters, handshakes, retransmits, resets, DNS, TLS SNI, VLAN tags, MTU, and rolling captures. Packet Path How packets move through local sockets, routing, neighbor lookup, firewalls, conntrack, qdisc, NIC queues, and return paths.

performance

Ceph Performance and Capacity Ceph performance model, capacity planning, BlueStore, OSD latency, network design, client behavior, benchmarks, and saturation troubleshooting. Inference Benchmarking Benchmark methodology for LLM inference with warmup, prompt/output distributions, concurrency sweeps, TTFT, ITL, throughput, quality gates, and benchmark anti-patterns. Linux Kernel Network Performance Linux kernel packet processing, NAPI, softirq, NIC queues, RPS, RFS, XPS, offloads, qdisc, drops, and practical network performance troubleshooting. Linux Memory Pressure and OOM Linux memory troubleshooting for RSS, VSZ, page cache, slab, THP, NUMA, swap, cgroup memory, PSI, and OOM killer behavior. Linux Performance Triage Runbooks Symptom-driven Linux runbooks for high CPU, high load, memory pressure, disk latency, softirq saturation, file descriptor exhaustion, and cgroup throttling. Linux Storage Health and Performance Linux storage observability, iostat, SMART, NVMe health, kernel I/O errors, discard, queue depth, latency, saturation, and failure response. ML Accelerators: GPU and TPU GPU and TPU fundamentals for ML workloads: parallelism, memory, precision, batching, utilization, data movement, and troubleshooting. ML Performance Engineering ML performance engineering with training-loop profiling, GPU utilization, memory bandwidth, activation checkpointing, FlashAttention, fused kernels, distributed training bottlenecks, inference throughput tuning, and cost/performance tradeoffs. PostgreSQL PostgreSQL architecture, MVCC, WAL, query planning, indexes, vacuum, backups, replication, and operations.

permissions

Linux Security Controls Linux security primitives for capabilities, seccomp, AppArmor, SELinux, PAM, auditd, sudoers, file capabilities, setuid, and container boundaries.

pgbouncer

Database and Search Examples Practical PostgreSQL, PgBouncer, and OpenSearch examples for queries, pooling, and cluster inspection. PgBouncer How PgBouncer works, pooling modes, sizing, HA placement, failover behavior, prepared statements, session state, observability, and operational runbooks.

pipelines

ML Data Pipelines and Feature Stores ML data engineering with dataset versioning, feature stores, lineage, data contracts, train/serve skew, point-in-time correctness, privacy, and reproducibility.

postgres

CloudNativePG How CloudNativePG runs PostgreSQL in Kubernetes, including clusters, services, failover, operator scaling, operator upgrades, backups, and operational cautions. Database and Search Examples Practical PostgreSQL, PgBouncer, and OpenSearch examples for queries, pooling, and cluster inspection. PgBouncer How PgBouncer works, pooling modes, sizing, HA placement, failover behavior, prepared statements, session state, observability, and operational runbooks. PostgreSQL PostgreSQL architecture, MVCC, WAL, query planning, indexes, vacuum, backups, replication, and operations. PostgreSQL Operations, HA, Replication, and Recovery Operational PostgreSQL guide covering HA managers, failover, physical and logical replication, sharding, backups, restore drills, WAL, high CPU, high RAM, and incident checks. PostgreSQL Zero-Downtime Upgrades on Kubernetes Zero-downtime and low-downtime PostgreSQL upgrade strategies on Kubernetes, including CloudNativePG rolling updates, major upgrades, logical replication cutovers, PgBouncer draining, and ordinary PostgreSQL runbooks. Storage Drives, RAID, and Database Performance SSD, HDD, NVMe, RAID 0/1/5/6/10, RAID performance, disk-failure recovery, LVM RAID, and PostgreSQL and Elasticsearch storage tradeoffs.

privacy

DNSSEC and DNS Privacy DNSSEC validation, chain of trust, DS/DNSKEY, signing failures, DNS over TLS, DNS over HTTPS, and what privacy does not solve. ML Security Threats Advanced ML security threats: prompt injection, jailbreaks, data poisoning, model extraction, membership inference, training data leakage, secrets in prompts, supply chain risk, tenant isolation, and secure RAG. ML Security and Privacy ML security and privacy risks including prompt injection, data exfiltration, model supply chain, poisoned retrieval, tenant isolation, PII, retention, and audit logging.

processes

Linux Processes and Threads Linux processes, threads, tasks, PIDs, TIDs, fork, exec, wait, zombies, signals, scheduling, cgroups, namespaces, and process troubleshooting.

prompts

ML Prompt Operations Prompt engineering operations with templates, versioning, structured outputs, injection resistance, system/developer/user boundaries, evals, and rollback. Tokenizer and Chat Template Compatibility Tokenizer, chat template, special token, stop sequence, tool schema, and generation config compatibility for reliable LLM inference.

provisioning

Network Boot and Automated Provisioning PXE, UEFI HTTP Boot, iPXE, DHCP, TFTP, automated Linux installs, Ubuntu autoinstall, cloud-init NoCloud, Kickstart, bare-metal provisioning, and troubleshooting.

proxy

Forward and Reverse Proxies Forward proxies, reverse proxies, CONNECT tunnels, transparent proxies, TLS interception, proxy headers, egress control, caching, environment variables, and troubleshooting. HTTP and Proxy Debugging Practical HTTP and proxy debugging with curl, headers, redirects, keepalive, chunking, HTTP/2, gRPC, WebSockets, proxy variables, and timeout alignment.

pytorch

PyTorch Fundamentals PyTorch fundamentals for tensors, modules, autograd, losses, optimizers, dataloaders, training loops, mixed precision, and checkpointing.

quantization

Quantized Serving Quantized LLM serving with weight quantization, activation quantization, KV-cache quantization, GGUF, AWQ, GPTQ, FP8, quality gates, and rollout checks.

rados

Ceph RADOS, CRUSH, and Placement RADOS objects, pools, placement groups, CRUSH rules, acting sets, PG autoscaling, and placement troubleshooting.

rag

Advanced RAG Advanced retrieval-augmented generation with hybrid retrieval, query planning, multi-hop retrieval, reranker architectures, GraphRAG, context compression, citation verification, agentic RAG, retrieval evals, and RAG security. Retrieval-Augmented Generation RAG systems with embeddings, chunking, vector search, retrieval, reranking, context assembly, citations, freshness, and evaluation.

raid

RAID, Multipath, and Device Mapper Linux md RAID, device mapper, dm-crypt/LUKS, multipath, NVMe multipath, WWIDs, path failover, and layered storage troubleshooting. Storage Drives, RAID, and Database Performance SSD, HDD, NVMe, RAID 0/1/5/6/10, RAID performance, disk-failure recovery, LVM RAID, and PostgreSQL and Elasticsearch storage tradeoffs.

rbd

Ceph Block, File, and Object Interfaces RBD, CephFS, and RGW mental models, command checks, snapshots, mirroring, MDS behavior, bucket gateways, and interface selection.

recovery

Ceph Operations and Recovery Ceph health triage, OSD failure response, recovery and backfill, scrub repair, maintenance flags, full ratios, and safe operational runbooks. Linux Package and Boot Recovery Debian and Ubuntu recovery runbooks for broken packages, bad kernels, initramfs failures, GRUB rescue, emergency mode, and rollback.

release

ML Evaluation and CI/CD ML evaluation harnesses, golden sets, regression gates, human review, release scorecards, canaries, and CI/CD for model, prompt, retrieval, and tool changes.

reliability

Troubleshooting and Error Handling Cross-technology troubleshooting and error handling for Linux, networking, DNS, Kubernetes, Istio, Ceph, PostgreSQL, and distributed systems operations.

replication

OpenSearch Operations, Replication, Sharding, and HA OpenSearch operations guide covering shards, replicas, cross-cluster replication, allocation awareness, snapshots, cluster-manager failover, and HA runbooks. PostgreSQL Operations, HA, Replication, and Recovery Operational PostgreSQL guide covering HA managers, failover, physical and logical replication, sharding, backups, restore drills, WAL, high CPU, high RAM, and incident checks.

resilience

Resilience, Timeouts, and Draining Practical network resilience patterns: timeout budgets, retries, backoff, connection pooling, keepalive, idle timeouts, load balancer draining, rolling restarts, DNS TTLs, and zero-downtime deploy behavior.

resolv-conf

resolv.conf Linux resolver configuration, nameservers, search domains, ndots, timeouts, attempts, rotation, and systemd-resolved behavior.

responsible-ai

Responsible AI and Governance Responsible AI governance with model cards, dataset cards, risk classification, human oversight, audit trails, fairness checks, red-team programs, release approval, incident response, and regulatory documentation.

retrieval

Advanced RAG Advanced retrieval-augmented generation with hybrid retrieval, query planning, multi-hop retrieval, reranker architectures, GraphRAG, context compression, citation verification, agentic RAG, retrieval evals, and RAG security.

rgw

Ceph Block, File, and Object Interfaces RBD, CephFS, and RGW mental models, command checks, snapshots, mirroring, MDS behavior, bucket gateways, and interface selection.

rook

Rook-Ceph Rook-Ceph architecture, CephCluster CRD, Kubernetes storage classes, CSI, toolbox usage, upgrades, and troubleshooting.

routing

BGP and Dynamic Routing BGP fundamentals for operators: ASNs, peering, route advertisement, route selection, communities, ECMP, anycast, and failure modes. Cloud Networking Cloud networking fundamentals for VPCs, subnets, route tables, security groups, private endpoints, peering, transit gateways, NAT, load balancers, and overlapping CIDRs. DHCP, Routers, and Switches DHCP-focused networking guide covering DORA, leases, options, default gateways, DNS options, relay agents, helper addresses, Option 82, VLANs, switches, routers, DHCP snooping, DHCPv6, and troubleshooting. Datacenter L2/L3 Operations Datacenter switching and routing concepts for host operators: LACP, MLAG, STP, ARP/NDP instability, EVPN/VXLAN, ECMP, anycast, route dampening, and fabric incident evidence. IP Addressing and Subnetting IPv4 and IPv6 addressing, CIDR, subnets, default gateways, private address space, source selection, and route troubleshooting. Routing, NAT, and Firewalls Routing tables, policy routing, NAT, connection tracking, firewall state, asymmetric paths, and load-balancer edge cases.

rsync

Linux Backup and File Transfer Linux backup and transfer notes covering rsync, scp, snapshot backups, consistency, restore testing, exclusions, permissions, and automation.

runbooks

Inference Runbooks Operational runbooks for LLM inference incidents: wrong output, high TTFT, slow inter-token latency, OOM, low throughput, queue buildup, cache pressure, tokenizer mismatch, and runtime regressions. Linux Performance Triage Runbooks Symptom-driven Linux runbooks for high CPU, high load, memory pressure, disk latency, softirq saturation, file descriptor exhaustion, and cgroup throttling. Scenario Labs Operational labs for practicing cross-layer debugging with symptoms, evidence, checks, and answers.

safety

ML Alignment and Evaluation Alignment, evaluation, RLHF, preference tuning, DPO, safety policy, red teaming, regression gates, calibration, and monitoring. ML Security and Privacy ML security and privacy risks including prompt injection, data exfiltration, model supply chain, poisoned retrieval, tenant isolation, PII, retention, and audit logging. Responsible AI and Governance Responsible AI governance with model cards, dataset cards, risk classification, human oversight, audit trails, fairness checks, red-team programs, release approval, incident response, and regulatory documentation.

saml

IdP, SAML, JWT, OAuth, and OIDC Identity provider basics, SAML assertions, OAuth 2.0 authorization, OpenID Connect authentication, JWT structure, validation checks, and troubleshooting.

scikit-learn

Classical ML Classical machine learning with linear models, logistic regression, trees, random forests, gradient boosting, SVMs, k-means, feature engineering, and tabular workflows.

scp

Linux Backup and File Transfer Linux backup and transfer notes covering rsync, scp, snapshot backups, consistency, restore testing, exclusions, permissions, and automation.

search

OpenSearch Operations, Replication, Sharding, and HA OpenSearch operations guide covering shards, replicas, cross-cluster replication, allocation awareness, snapshots, cluster-manager failover, and HA runbooks. Retrieval-Augmented Generation RAG systems with embeddings, chunking, vector search, retrieval, reranking, context assembly, citations, freshness, and evaluation.

security

IdP, SAML, JWT, OAuth, and OIDC Identity provider basics, SAML assertions, OAuth 2.0 authorization, OpenID Connect authentication, JWT structure, validation checks, and troubleshooting. Identity and Access Identity-provider, federation, SSO, SAML, OAuth, OpenID Connect, JWT, token validation, and access-control study guide. Istio Security, mTLS, and Policy Istio workload identity, mTLS, PeerAuthentication, AuthorizationPolicy, RequestAuthentication, JWT validation, trust domains, and policy debugging. Kubernetes NetworkPolicy NetworkPolicy isolation, ingress and egress rules, podSelector, namespaceSelector, ipBlock, default deny, DNS egress, CNI enforcement, and policy debugging. Linux Security Controls Linux security primitives for capabilities, seccomp, AppArmor, SELinux, PAM, auditd, sudoers, file capabilities, setuid, and container boundaries. ML Security Threats Advanced ML security threats: prompt injection, jailbreaks, data poisoning, model extraction, membership inference, training data leakage, secrets in prompts, supply chain risk, tenant isolation, and secure RAG. ML Security and Privacy ML security and privacy risks including prompt injection, data exfiltration, model supply chain, poisoned retrieval, tenant isolation, PII, retention, and audit logging. SSH Access OpenSSH server administration on Ubuntu: sshd config, keys, authentication, host keys, logs, access control, and troubleshooting. Users, Permissions, and sudo Linux identities, groups, file modes, ownership, sudo, service users, locked accounts, ACLs, and permission troubleshooting on Ubuntu. Zero-Trust Networking Network security patterns that combine host firewall policy, nftables, mTLS, certificate rotation, SNI, ALPN, service identity, SSH hardening, auditd, SELinux, AppArmor, and real traffic debugging.

service-mesh

Istio Istio service mesh fundamentals: control plane, data plane, sidecar mode, ambient mode, traffic management, security, observability, and operations. Istio Service Mesh Service mesh architecture, request paths, Envoy sidecars, ambient ztunnel and waypoint proxies, mTLS, policy, telemetry, and troubleshooting. Istio Service Mesh Examples Practical Istio examples for VirtualService traffic splitting, DestinationRule subsets, and AuthorizationPolicy.

services

Kubernetes Services and EndpointSlices Service types, selectors, ClusterIP, NodePort, LoadBalancer, headless Services, EndpointSlices, kube-proxy, readiness, and service debugging.

serving

Inference Engine Comparison Comparison guide for vLLM, TensorRT-LLM, Hugging Face TGI, llama.cpp, SGLang, Ollama, OpenAI-compatible APIs, quantization, adapters, and migration checks. LLM Inference Systems Production LLM inference systems: model files, weights, memory, inference engines, vLLM, TensorRT-LLM, TGI, llama.cpp, SGLang, Ollama, KV cache, PagedAttention, batching, quantization, routing, performance tests, and runbooks. ML Serving, Inference, and vLLM Production ML inference with model servers, batching, streaming, KV cache, autoscaling, canaries, inference optimization, and deep vLLM operations. Quantized Serving Quantized LLM serving with weight quantization, activation quantization, KV-cache quantization, GGUF, AWQ, GPTQ, FP8, quality gates, and rollout checks.

sockets

Linux Sockets and IPC Linux sockets, TCP, UDP, Unix domain sockets, socket files, listen queues, buffers, file descriptors, pipes, signals, shared memory, and IPC troubleshooting. TCP and Sockets TCP state, sockets, listen queues, receive/send buffers, TIME_WAIT, retransmits, keepalive, ephemeral ports, and Linux observability.

ssh

SSH Access OpenSSH server administration on Ubuntu: sshd config, keys, authentication, host keys, logs, access control, and troubleshooting.

storage

Ceph Ceph distributed storage architecture, RADOS, OSDs, monitors, managers, pools, placement groups, CRUSH, CephFS, RBD, RGW, and operations. Ceph Performance and Capacity Ceph performance model, capacity planning, BlueStore, OSD latency, network design, client behavior, benchmarks, and saturation troubleshooting. Ceph RADOS, CRUSH, and Placement RADOS objects, pools, placement groups, CRUSH rules, acting sets, PG autoscaling, and placement troubleshooting. Ceph Storage Examples Practical Ceph examples for cluster health, replicated pool creation, and RBD image operations. Databases Database fundamentals, modeling, indexes, transactions, replication, and operations. Kubernetes Examples Practical Kubernetes examples for Deployments, Services, PodDisruptionBudgets, NetworkPolicy, and StatefulSet storage. Kubernetes Storage and Upgrades Persistent storage, CSI, StatefulSets, volume lifecycle, and safe Kubernetes upgrade practices. Linux Backup and File Transfer Linux backup and transfer notes covering rsync, scp, snapshot backups, consistency, restore testing, exclusions, permissions, and automation. Linux Block Devices and Partitioning Linux block devices, NVMe and SCSI naming, partitions, GPT, UUIDs, labels, udev, stable device paths, and safe disk identification. Linux Filesystems and IO VFS, inodes, dentries, page cache, block devices, mounts, filesystem checks, IO schedulers, and storage troubleshooting. Linux LVM Logical Volume Manager fundamentals, advanced operations, resizing, thin provisioning, snapshots, migration, and troubleshooting. Linux Mounts and fstab Linux mounts, findmnt, /etc/fstab, UUIDs, systemd mount units, automounts, bind mounts, mount options, and boot-safe storage configuration. Linux Storage Health and Performance Linux storage observability, iostat, SMART, NVMe health, kernel I/O errors, discard, queue depth, latency, saturation, and failure response. RAID, Multipath, and Device Mapper Linux md RAID, device mapper, dm-crypt/LUKS, multipath, NVMe multipath, WWIDs, path failover, and layered storage troubleshooting. Rook-Ceph Rook-Ceph architecture, CephCluster CRD, Kubernetes storage classes, CSI, toolbox usage, upgrades, and troubleshooting. Storage Drives, RAID, and Database Performance SSD, HDD, NVMe, RAID 0/1/5/6/10, RAID performance, disk-failure recovery, LVM RAID, and PostgreSQL and Elasticsearch storage tradeoffs. ext4, XFS, and Filesystem Repair ext4 and XFS operations, mkfs, fsck, xfs_repair, online growth, inode usage, journals, quotas, discard, and safe repair workflows.

study

Cross-Topic Study Paths Cross-topic paths for debugging a 504, Pod networking, Linux performance, TLS and mTLS, and cloud egress. Foundational Study Review A cross-topic checklist for reviewing whether the guide covers the core mental models behind Linux, networking, DNS, Kubernetes, identity, databases, Ceph, Istio, and troubleshooting. Scenario Labs Operational labs for practicing cross-layer debugging with symptoms, evidence, checks, and answers.

study-system

Home A study-first technical wiki for infrastructure, networking, databases, and engineering notes.

switching

DHCP, Routers, and Switches DHCP-focused networking guide covering DORA, leases, options, default gateways, DNS options, relay agents, helper addresses, Option 82, VLANs, switches, routers, DHCP snooping, DHCPv6, and troubleshooting. Datacenter L2/L3 Operations Datacenter switching and routing concepts for host operators: LACP, MLAG, STP, ARP/NDP instability, EVPN/VXLAN, ECMP, anycast, route dampening, and fabric incident evidence. Switching, VLANs, and Hosts Layer 2 switching, MAC tables, VLAN access and trunk ports, Linux bridges, 802.1Q tagging, and /etc/hosts name overrides.

syscalls

Linux System Call Debugging Linux syscall debugging with strace, errno, blocking calls, file and socket syscalls, poll, epoll, futexes, and production triage boundaries.

systemd

Linux Boot and Userspace Firmware, bootloader, kernel command line, initramfs, root filesystem handoff, PID 1, services, and boot troubleshooting. Linux Mounts and fstab Linux mounts, findmnt, /etc/fstab, UUIDs, systemd mount units, automounts, bind mounts, mount options, and boot-safe storage configuration. Linux Operations Examples Practical Linux examples for systemd services, timers, rsync snapshot backups, and nftables host firewalls. Scheduled Automation Cronjobs, anacron, systemd timers, user timers, environment pitfalls, idempotent jobs, logs, locking, and automation troubleshooting. systemd systemd units, services, targets, dependencies, timers, journals, cgroups, resource controls, and troubleshooting. systemd Networking systemd-networkd, systemd-resolved, .network, .netdev, .link files, network targets, wait-online behavior, and operational troubleshooting. systemd Socket Activation and Network Services systemd socket activation, ListenStream, ListenDatagram, Accept modes, service dependencies, restart behavior, resource controls, and network sandboxing.

systems

MLOps Systems MLOps systems with model registries, feature stores, training pipelines, artifact versioning, reproducibility, batch and online inference, canaries, shadow evaluation, rollback, and cost governance.

tabular

Classical ML Classical machine learning with linear models, logistic regression, trees, random forests, gradient boosting, SVMs, k-means, feature engineering, and tabular workflows.

tcp

Linux TCP Kernel Tuning Linux TCP listen queues, SYN backlog, socket buffers, ephemeral ports, TIME_WAIT, keepalives, conntrack pressure, and safe sysctl tuning. TCP and Sockets TCP state, sockets, listen queues, receive/send buffers, TIME_WAIT, retransmits, keepalive, ephemeral ports, and Linux observability. TCP, TLS, and HTTP Transport and application handshake layers: TCP state, retransmits, flow control, congestion control, TLS SNI/certificates, and HTTP behavior.

tcpdump

Packet Capture and Analysis Practical tcpdump and Wireshark packet analysis for filters, handshakes, retransmits, resets, DNS, TLS SNI, VLAN tags, MTU, and rolling captures.

tensors

Math for ML Practical math for machine learning: vectors, matrices, tensors, dot products, cosine similarity, gradients, softmax, cross entropy, KL divergence, probability, and attention intuition. PyTorch Fundamentals PyTorch fundamentals for tensors, modules, autograd, losses, optimizers, dataloaders, training loops, mixed precision, and checkpointing.

testing

ML Evaluation Mastery Advanced ML evaluation with unit evals, golden sets, model-graded evals, human evals, pairwise preference evals, safety evals, regression gates, slice metrics, statistical confidence, and contamination controls.

threads

Linux Processes and Threads Linux processes, threads, tasks, PIDs, TIDs, fork, exec, wait, zombies, signals, scheduling, cgroups, namespaces, and process troubleshooting.

threats

ML Security Threats Advanced ML security threats: prompt injection, jailbreaks, data poisoning, model extraction, membership inference, training data leakage, secrets in prompts, supply chain risk, tenant isolation, and secure RAG.

time

Time, Hostname, and Identity Time synchronization, timezone, hostname, machine-id, DNS identity, certificates, logs, Kerberos sensitivity, and Ubuntu host identity operations.

tls

Certificates and HTTPS TLS certificates, HTTPS handshakes, chains of trust, SANs, SNI, OCSP, CA stores, and Ubuntu certificate operations. HTTP and Proxy Debugging Practical HTTP and proxy debugging with curl, headers, redirects, keepalive, chunking, HTTP/2, gRPC, WebSockets, proxy variables, and timeout alignment. Networking TLS and mTLS Examples Practical networking examples for certificate inspection and mTLS requests. TCP, TLS, and HTTP Transport and application handshake layers: TCP state, retransmits, flow control, congestion control, TLS SNI/certificates, and HTTP behavior. Zero-Trust Networking Network security patterns that combine host firewall policy, nftables, mTLS, certificate rotation, SNI, ALPN, service identity, SSH hardening, auditd, SELinux, AppArmor, and real traffic debugging.

tokenizer

Tokenizer and Chat Template Compatibility Tokenizer, chat template, special token, stop sequence, tool schema, and generation config compatibility for reliable LLM inference.

tools

Advanced Agents Advanced agent engineering with ReAct, planning, reflection, tool routing, multi-agent systems, durable execution, memory, sandboxing, approval workflows, trajectory evaluation, and failure recovery. ML Agents and Tool Use Agentic ML systems with planning loops, tools, state, memory, idempotency, guardrails, human approval, and evaluation.

tpu

ML Accelerators: GPU and TPU GPU and TPU fundamentals for ML workloads: parallelism, memory, precision, batching, utilization, data movement, and troubleshooting.

tracing

Linux eBPF and Tracing Practical Linux eBPF tracing with tracepoints, kprobes, uprobes, bpftrace, BCC, tc, XDP, and production-safe observability boundaries.

traffic-management

Istio Traffic Management Istio VirtualService, DestinationRule, subsets, retries, timeouts, fault injection, traffic splits, ServiceEntry, and routing troubleshooting.

training

Deep Learning Fundamentals Deep learning fundamentals: neural networks, layers, activations, embeddings, CNNs, RNNs, transformers, optimizers, normalization, regularization, initialization, and training stability. LLM Training Lifecycle LLM lifecycle from pretraining and continued pretraining to SFT, RLHF, DPO, RLAIF, preference data, synthetic data, data filtering, and stage-specific evaluation. PyTorch Fundamentals PyTorch fundamentals for tensors, modules, autograd, losses, optimizers, dataloaders, training loops, mixed precision, and checkpointing.

transformers

Advanced ML Architectures Advanced model architectures including Mixture of Experts, retrieval-augmented models, state space models, diffusion transformers, sparse attention, long-context architectures, and encoder-only, decoder-only, and encoder-decoder tradeoffs. Long-Context Serving Long-context LLM serving with RoPE scaling, sliding-window attention, sink tokens, lost-in-the-middle behavior, KV-cache growth, prompt budgeting, and long-context evals. ML Models, Types, and Weights Model families, model types, parameters, weights, checkpoints, tokenizers, embeddings, transformers, diffusion models, and inference boundaries. MoE Inference Mixture-of-Experts inference with active vs total parameters, expert routing, expert parallelism, all-to-all communication, load balance, capacity, KV cache, and serving tradeoffs. Transformer Internals Transformer internals covering tokenization, embeddings, positional encodings, RoPE, self-attention, multi-head attention, MLP blocks, LayerNorm/RMSNorm, decoder-only models, KV cache, context windows, and MoE basics.

troubleshooting

BGP and Dynamic Routing BGP fundamentals for operators: ASNs, peering, route advertisement, route selection, communities, ECMP, anycast, and failure modes. Ceph Ceph distributed storage architecture, RADOS, OSDs, monitors, managers, pools, placement groups, CRUSH, CephFS, RBD, RGW, and operations. Ceph Operations and Recovery Ceph health triage, OSD failure response, recovery and backfill, scrub repair, maintenance flags, full ratios, and safe operational runbooks. Cloud Networking Cloud networking fundamentals for VPCs, subnets, route tables, security groups, private endpoints, peering, transit gateways, NAT, load balancers, and overlapping CIDRs. Cross-Layer Incident Runbooks Operational runbooks that trace application symptoms through DNS, TCP, TLS, proxies, Linux hosts, Kubernetes Services, CNI, NAT, and cloud networking. Cross-Topic Study Paths Cross-topic paths for debugging a 504, Pod networking, Linux performance, TLS and mTLS, and cloud egress. DHCP, Routers, and Switches DHCP-focused networking guide covering DORA, leases, options, default gateways, DNS options, relay agents, helper addresses, Option 82, VLANs, switches, routers, DHCP snooping, DHCPv6, and troubleshooting. DNS Name resolution flow, DNS records, delegation, caching, negative answers, and operational debugging. DNS Records, Responses, and Transport DNS record types, response codes, EDNS, UDP and TCP transport, truncation, reverse DNS, mail records, and operational debugging. DNS Resolution and Caching How resolver lookup paths, caches, TTLs, negative answers, CNAME chains, and client search behavior shape DNS outcomes. Datacenter L2/L3 Operations Datacenter switching and routing concepts for host operators: LACP, MLAG, STP, ARP/NDP instability, EVPN/VXLAN, ECMP, anycast, route dampening, and fabric incident evidence. Firewalls, iptables, and Netfilter Linux firewall fundamentals: netfilter hooks, nftables, iptables, chains, tables, conntrack, NAT, rule ordering, logging, persistence, and troubleshooting. Forward and Reverse Proxies Forward proxies, reverse proxies, CONNECT tunnels, transparent proxies, TLS interception, proxy headers, egress control, caching, environment variables, and troubleshooting. Foundational Study Review A cross-topic checklist for reviewing whether the guide covers the core mental models behind Linux, networking, DNS, Kubernetes, identity, databases, Ceph, Istio, and troubleshooting. HTTP and Proxy Debugging Practical HTTP and proxy debugging with curl, headers, redirects, keepalive, chunking, HTTP/2, gRPC, WebSockets, proxy variables, and timeout alignment. ICMP, MTU, and Path Testing ICMP, ping, traceroute, path MTU discovery, fragmentation, tunnel overhead, packet loss, jitter, and practical path testing. IP Addressing and Subnetting IPv4 and IPv6 addressing, CIDR, subnets, default gateways, private address space, source selection, and route troubleshooting. IPv6 Operations Operational IPv6 fundamentals: SLAAC, DHCPv6, Router Advertisements, NDP, link-local addresses, privacy addresses, dual-stack, NAT64, DNS AAAA, and firewalling. Incident Entry Points Symptom-first entry points for timeouts, resets, DNS works on the node but not in Pods, large payload hangs, and intermittent 5xx failures. Istio Observability and Troubleshooting Istio metrics, access logs, traces, proxy sync, xDS inspection, response flags, common 503 and policy failures, and practical debugging flows. Kubernetes DNS and CoreDNS Kubernetes DNS names, CoreDNS, kube-dns compatibility, Pod resolv.conf, dnsPolicy, search paths, ndots, forwarding, and DNS troubleshooting. Linux Linux fundamentals for developers and operators: processes, fork/exec, memory, CPU, kernel params, caches, paging, GPUs, and troubleshooting. Linux Block Devices and Partitioning Linux block devices, NVMe and SCSI naming, partitions, GPT, UUIDs, labels, udev, stable device paths, and safe disk identification. Linux GPU Drivers Linux GPU driver stacks for AMD and NVIDIA, including kernel modules, firmware, Mesa, ROCm, CUDA, nvidia-smi, Secure Boot, containers, and troubleshooting. Linux Kernel Modules and Devices Linux kernel modules, built-in drivers, modprobe, module aliases, parameters, blacklists, sysfs, devtmpfs, udev, device nodes, initramfs, Secure Boot, DKMS, and troubleshooting. Linux Kernel Network Performance Linux kernel packet processing, NAPI, softirq, NIC queues, RPS, RFS, XPS, offloads, qdisc, drops, and practical network performance troubleshooting. Linux LVM Logical Volume Manager fundamentals, advanced operations, resizing, thin provisioning, snapshots, migration, and troubleshooting. Linux Memory Pressure and OOM Linux memory troubleshooting for RSS, VSZ, page cache, slab, THP, NUMA, swap, cgroup memory, PSI, and OOM killer behavior. Linux Network Stack Linux sockets, routes, neighbor tables, netfilter, conntrack, qdisc, NIC queues, namespaces, and network troubleshooting. Linux Package and Boot Recovery Debian and Ubuntu recovery runbooks for broken packages, bad kernels, initramfs failures, GRUB rescue, emergency mode, and rollback. Linux Performance Triage Runbooks Symptom-driven Linux runbooks for high CPU, high load, memory pressure, disk latency, softirq saturation, file descriptor exhaustion, and cgroup throttling. Linux Processes and Threads Linux processes, threads, tasks, PIDs, TIDs, fork, exec, wait, zombies, signals, scheduling, cgroups, namespaces, and process troubleshooting. Linux Sockets and IPC Linux sockets, TCP, UDP, Unix domain sockets, socket files, listen queues, buffers, file descriptors, pipes, signals, shared memory, and IPC troubleshooting. Linux Storage Health and Performance Linux storage observability, iostat, SMART, NVMe health, kernel I/O errors, discard, queue depth, latency, saturation, and failure response. Linux System Call Debugging Linux syscall debugging with strace, errno, blocking calls, file and socket syscalls, poll, epoll, futexes, and production triage boundaries. Linux TCP Kernel Tuning Linux TCP listen queues, SYN backlog, socket buffers, ephemeral ports, TIME_WAIT, keepalives, conntrack pressure, and safe sysctl tuning. Linux eBPF and Tracing Practical Linux eBPF tracing with tracepoints, kprobes, uprobes, bpftrace, BCC, tc, XDP, and production-safe observability boundaries. Load Balancers and Proxies L4 and L7 load balancing, reverse proxies, health checks, TLS termination, source IP preservation, PROXY protocol, headers, and timeout failures. Logs and Observability Linux logs, journald, syslog, dmesg, service status, boot logs, log rotation, metrics, and incident evidence collection. NAT Gateways and Network Address Translation Deep operational guide to NAT, NAT gateways, SNAT, DNAT, PAT, masquerade, conntrack, ephemeral ports, cloud egress, hairpin NAT, and NAT troubleshooting. Network Namespaces and Virtual Networking Linux network namespaces, veth pairs, bridges, macvlan, ipvlan, tun/tap, VXLAN, overlays, and CNI-style packet paths. Networking Practical systems networking: OSI layers, NICs, ARP, IP routing, TCP/UDP, DNS, TLS, and packet debugging. Packet Capture and Analysis Practical tcpdump and Wireshark packet analysis for filters, handshakes, retransmits, resets, DNS, TLS SNI, VLAN tags, MTU, and rolling captures. PostgreSQL Operations, HA, Replication, and Recovery Operational PostgreSQL guide covering HA managers, failover, physical and logical replication, sharding, backups, restore drills, WAL, high CPU, high RAM, and incident checks. Request Path A master walkthrough of one request through DNS, client behavior, TCP, TLS, proxies, Kubernetes Service routing, CNI, Pod, application, database, and the response path. Resilience, Timeouts, and Draining Practical network resilience patterns: timeout budgets, retries, backoff, connection pooling, keepalive, idle timeouts, load balancer draining, rolling restarts, DNS TTLs, and zero-downtime deploy behavior. Scenario Labs Operational labs for practicing cross-layer debugging with symptoms, evidence, checks, and answers. Troubleshooting First checks and failure paths for common Kubernetes incidents. Troubleshooting Examples Practical troubleshooting examples for repeatable incident capture and evidence preservation. Troubleshooting and Error Handling Cross-technology troubleshooting and error handling for Linux, networking, DNS, Kubernetes, Istio, Ceph, PostgreSQL, and distributed systems operations. UDP, QUIC, and Connectionless Traffic UDP behavior, DNS and DHCP traffic, QUIC, connection tracking, timeouts, packet loss, retries, and operational debugging. VPNs and IPsec Tunnels VPN fundamentals, IPsec tunnel mode, IKEv2, ESP, NAT-T, traffic selectors, route-based and policy-based tunnels, split tunneling, MTU, and operational troubleshooting. ext4, XFS, and Filesystem Repair ext4 and XFS operations, mkfs, fsck, xfs_repair, online growth, inode usage, journals, quotas, discard, and safe repair workflows. resolv.conf Linux resolver configuration, nameservers, search domains, ndots, timeouts, attempts, rotation, and systemd-resolved behavior. systemd systemd units, services, targets, dependencies, timers, journals, cgroups, resource controls, and troubleshooting. systemd Networking systemd-networkd, systemd-resolved, .network, .netdev, .link files, network targets, wait-online behavior, and operational troubleshooting. systemd Socket Activation and Network Services systemd socket activation, ListenStream, ListenDatagram, Accept modes, service dependencies, restart behavior, resource controls, and network sandboxing.

ubuntu

Debian and Ubuntu Operations Ubuntu-first Linux operations: apt, dpkg, systemd, journald, netplan, ufw, CA certificates, logs, services, and package troubleshooting. Linux Package and Boot Recovery Debian and Ubuntu recovery runbooks for broken packages, bad kernels, initramfs failures, GRUB rescue, emergency mode, and rollback. SSH Access OpenSSH server administration on Ubuntu: sshd config, keys, authentication, host keys, logs, access control, and troubleshooting. Time, Hostname, and Identity Time synchronization, timezone, hostname, machine-id, DNS identity, certificates, logs, Kerberos sensitivity, and Ubuntu host identity operations. Users, Permissions, and sudo Linux identities, groups, file modes, ownership, sudo, service users, locked accounts, ACLs, and permission troubleshooting on Ubuntu.

udp

UDP, QUIC, and Connectionless Traffic UDP behavior, DNS and DHCP traffic, QUIC, connection tracking, timeouts, packet loss, retries, and operational debugging.

upgrades

Istio Zero Downtime Upgrades on Kubernetes Operational runbook for low-risk Istio upgrades on Kubernetes using canary control planes, revisions, revision tags, workload restarts, gateway canaries, rollback, PDBs, and validation gates. Kubernetes Storage and Upgrades Persistent storage, CSI, StatefulSets, volume lifecycle, and safe Kubernetes upgrade practices. PostgreSQL Zero-Downtime Upgrades on Kubernetes Zero-downtime and low-downtime PostgreSQL upgrade strategies on Kubernetes, including CloudNativePG rolling updates, major upgrades, logical replication cutovers, PgBouncer draining, and ordinary PostgreSQL runbooks.

virtualization

Containerization, OCI, and VMs Container fundamentals, OCI image/runtime/distribution standards, Linux namespaces, cgroups, overlay layers, bridge networking, macOS and Windows container behavior, KVM, hypervisors, and VM/container tradeoffs.

vision

Multimodal ML Multimodal ML with vision, audio, speech-to-text, text-to-speech, vision-language models, image embeddings, OCR pipelines, multimodal RAG, and video model basics.

vlan

Switching, VLANs, and Hosts Layer 2 switching, MAC tables, VLAN access and trunk ports, Linux bridges, 802.1Q tagging, and /etc/hosts name overrides.

vllm

Advanced Inference and vLLM Advanced LLM inference with vLLM, PagedAttention, continuous batching, disaggregated prefill, chunked prefill, speculative decoding, prefix caching, KV-cache math, tensor and pipeline parallelism, quantized serving, LoRA serving, and autoscaling. LLM Inference Systems Production LLM inference systems: model files, weights, memory, inference engines, vLLM, TensorRT-LLM, TGI, llama.cpp, SGLang, Ollama, KV cache, PagedAttention, batching, quantization, routing, performance tests, and runbooks. ML Serving, Inference, and vLLM Production ML inference with model servers, batching, streaming, KV cache, autoscaling, canaries, inference optimization, and deep vLLM operations. vLLM Operations Operational guide for vLLM serving with scheduler concepts, PagedAttention, KV cache, prefix caching, speculative decoding, parallelism, metrics, flags, and runbooks.

vpn

VPNs and IPsec Tunnels VPN fundamentals, IPsec tunnel mode, IKEv2, ESP, NAT-T, traffic selectors, route-based and policy-based tunnels, split tunneling, MTU, and operational troubleshooting.

weights

ML Models, Types, and Weights Model families, model types, parameters, weights, checkpoints, tokenizers, embeddings, transformers, diffusion models, and inference boundaries. Model Memory Math Practical LLM memory math for weights, activations, KV cache, optimizer state, model loading, quantization, model sizes, and serving capacity planning.

wireshark

Packet Capture and Analysis Practical tcpdump and Wireshark packet analysis for filters, handshakes, retransmits, resets, DNS, TLS SNI, VLAN tags, MTU, and rolling captures.

zero-downtime

Resilience, Timeouts, and Draining Practical network resilience patterns: timeout budgets, retries, backoff, connection pooling, keepalive, idle timeouts, load balancer draining, rolling restarts, DNS TTLs, and zero-downtime deploy behavior.

zones

Authoritative DNS and Zones Zones, delegations, NS records, SOA serials, glue, apex constraints, wildcard behavior, and authoritative debugging.