A record
The DNS record type that maps a hostname to an IPv4 address. The fundamental routing primitive of the internet.
An A record (address record) is the DNS entry that maps a hostname to an IPv4 address. A example.com 93.184.216.34 tells resolvers "when someone asks for example.com, give them 93.184.216.34."
Anatomy
example.com. A 93.184.216.34 ; TTL 3600
- Name (
example.com.): the hostname being defined. - Type (
A): IPv4 address mapping. - Value (
93.184.216.34): the IPv4 the hostname resolves to. - TTL (3600): how long resolvers should cache this answer in seconds.
The IPv6 equivalent is AAAA. A and AAAA records are the only DNS record types that resolve directly to IP addresses; CNAMEs delegate to other names.
When to use an A record
- You're publishing a host that doesn't change IP often (a static IP, an anycast IP).
- You're working at the apex of a domain and can't use a CNAME.
When NOT to use one
- The IP changes often (rotating load balancer, cloud-managed service). Use a CNAME to a stable hostname instead.
- Your provider gives you a hostname (
d-aabbcc.cloudfront.net), not an IP. Use a CNAME.
Multiple A records
You can have several A records for the same hostname. Resolvers return all of them; clients typically connect to one (the first, often randomized). This is the cheapest form of DNS-based load balancing and is how Cloudflare, Route 53, and others spread traffic across multiple edge IPs.