DevOps · interactive

DNS records

Your domain's zone is a small table of records: A and AAAA for addresses, CNAME for aliases, MX for mail, TXT for verification and email policy, NS for who's in charge. Run a few lookups against it.

name	type	value	TTL
example.com	A	93.184.216.34	300
example.com	AAAA	2606:2800:220:1::248	300
www.example.com	CNAME	example.com	3600
api.example.com	CNAME	lb-123.eu-west-1.elb.amazonaws.com	60
example.com	MX	10 mail.example.com	3600
example.com	TXT	v=spf1 include:_spf.google.com -all	3600
example.com	NS	ns1.dnsprovider.net	86400

$ dig www.example.com A

www.example.com CNAME → example.com
example.com A → 93.184.216.34

A CNAME says “ask about this other name instead”, so the lookup takes another step. Fine for subdomains; the bare domain can't be a CNAME.

Lookup

Step 2 of 4 · read left to right

1
A, AAAA: names to addresses
The basic answer: an IPv4 or IPv6 address. A name can have several for simple load spreading.
dig +short example.com
2
CNAME: follow another name
Point www or api at a load balancer or CDN whose IPs change. Not allowed at the apex; providers offer ALIAS/ANAME instead.
A CNAME can't coexist with other records on that name.
3
MX and TXT
MX says where mail goes. TXT carries SPF, DKIM, DMARC and domain-verification tokens.
Missing SPF/DMARC sends your mail to spam.
4
TTL decides how fast changes spread
Resolvers cache answers for the TTL. Lower it a day before a migration, then raise it again.
Manage zones as code (Terraform, OctoDNS).

In production

Tools and technologies

Every domain is managed through a zone like this.

Not tied to one language — use these names when you search docs or design a system.