DNS Examples

These examples complement DNS, resolution and caching, authoritative zones, and DNS records, responses, and transport.

DNS Zone Example

A minimal authoritative zone shape showing SOA, NS, glue-adjacent host records, web records, mail records, and a service record:

$ORIGIN example.com.
$TTL 300
@ IN SOA ns1.example.com. dns-admin.example.com. (
  2026052301 ; serial
  3600       ; refresh
  600        ; retry
  1209600    ; expire
  300        ; negative cache TTL
)

@    IN NS ns1.example.com.
@    IN NS ns2.example.com.
ns1  IN A  203.0.113.10
ns2  IN A  203.0.113.11

@    IN A     203.0.113.20
www  IN CNAME example.com.
api  IN A     203.0.113.30

@    IN MX 10 mail.example.com.
mail IN A     203.0.113.40

_nats._tcp.cluster IN SRV 10 10 6222 nats-0.nats-headless.svc.example.com.

Resolver debugging comparison:

getent hosts api.example.com
dig @127.0.0.53 api.example.com A
dig @1.1.1.1 api.example.com A
dig @ns1.example.com api.example.com A +norecurse
dig +trace api.example.com

Study Cards

Question

Why include SOA and NS records in a DNS zone example?

Answer

They show the zone authority, serial policy, and authoritative nameservers.

Question

Why compare resolver answers from multiple servers?

Answer

It separates local cache or stub resolver behavior from authoritative and public recursive resolver behavior.

Question

Why use +norecurse against an authoritative server?

Answer

It verifies the zone data served by that authority without asking it to recurse elsewhere.

References

DNS Records, Responses, and Transport