A Record — DNS & Security Glossary

An A record (Address record) is a DNS record that maps a fully qualified domain name (FQDN) to an IPv4 address. It is the most fundamental DNS record type — when a browser resolves example.com, it is ultimately looking for an A record (or AAAA for IPv6) to find the server to connect to.

Format

example.com.      3600  IN  A  93.184.216.34
www.example.com.  3600  IN  A  93.184.216.34
api.example.com.  300   IN  A  203.0.113.42

Fields: hostname TTL class(IN) type(A) IPv4-address

Multiple A Records

Publishing multiple A records for the same hostname implements DNS round-robin — each query returns all records, typically shuffled, so clients distribute across multiple IPs:

example.com.  300  IN  A  10.0.0.1
example.com.  300  IN  A  10.0.0.2
example.com.  300  IN  A  10.0.0.3

A vs CNAME

A record: maps directly to an IP — can be used at the domain apex (@)
CNAME: maps to another hostname — cannot be used at the domain apex

Use A records for servers you control directly. Use CNAME for subdomains pointing at CDNs, SaaS platforms, or load balancers where the IP may change.