DNS Records Explained: A, AAAA, CNAME, MX, and More

DNS is the phone book of the internet. Understanding DNS record types is essential for deploying websites, configuring email, and debugging connectivity issues.

How DNS Works

When you visit example.com, your browser asks a DNS resolver to translate that domain into an IP address. The resolver queries authoritative name servers, caches the result, and returns the IP.

Record Types

A Record

Maps a domain to an IPv4 address. The most fundamental record type.

example.com.    A    93.184.216.34

AAAA Record

Maps a domain to an IPv6 address.

example.com.    AAAA    2606:2800:220:1:248:1893:25c8:1946

CNAME Record

Creates an alias from one domain to another. Cannot coexist with other records at the same name.

www.example.com.    CNAME    example.com.

MX Record

Directs email to mail servers. Priority number determines preference (lower = higher priority).

example.com.    MX    10 mail1.example.com.
example.com.    MX    20 mail2.example.com.

TXT Record

Holds arbitrary text. Used for email authentication (SPF, DKIM, DMARC), domain verification, and more.

example.com.    TXT    "v=spf1 include:_spf.google.com ~all"

NS Record

Delegates a domain to specific name servers.

example.com.    NS    ns1.cloudflare.com.

SOA Record

Start of Authority — contains zone metadata like serial number, refresh intervals, and the primary name server.

TTL (Time to Live)

Every record has a TTL in seconds. Lower TTL means faster propagation of changes but more DNS queries. Common values: 300 (5 min) for dynamic records, 86400 (1 day) for stable records.

Debugging DNS

Use our DNS Lookup tool to query any record type for any domain. From the command line:

Query A records
dig example.com A

Query all records
dig example.com ANY

Trace the full resolution path
dig +trace example.com

Common Mistakes

CNAME at the apex — you can't put a CNAME on the root domain (example.com). Use an ALIAS/ANAME record if your DNS provider supports it, or use A records. Missing trailing dot — in zone files, domain names without a trailing dot are relative to the zone origin. Always use the trailing dot for absolute names. Forgetting to update TTL before migration — lower TTL to 300 seconds well before a DNS migration so changes propagate quickly.

Conclusion

DNS is deceptively simple on the surface but nuanced in practice. Know your record types, understand TTL implications, and use diagnostic tools to verify your configuration.