What Is an A Record? Mapping a Name to an IP
An A record is a DNS entry that maps a hostname directly to an IPv4 address, telling resolvers which address to connect to for that name.
The A record is the most basic DNS mapping: a name to an address. Its IPv6 counterpart is the AAAA record. When you point a domain at a specific server IP, you create an A record, and deploys that change the target server update it.
Name to address
An A record says "this hostname lives at this IPv4 address." A resolver returns that address so the client can open a connection directly, with no further alias to follow.
A versus AAAA versus CNAME
- A maps a name to an IPv4 address.
- AAAA maps a name to an IPv6 address.
- CNAME aliases a name to another name instead of an address.
A records at the apex
Unlike a CNAME, an A record can live at the apex domain, which is why root domains often use an A record or a provider alias pointing at a fixed address.
A records in deployments
Pointing a domain at a specific load balancer or server IP means setting an A record to that address. Changing infrastructure with a fixed IP is just an A record update.
Risks of pinning an IP
Because an A record hardcodes an address, it breaks if the underlying IP changes. Platforms with rotating addresses prefer a CNAME so the target can move without touching your record.
Propagation on change
Updating an A record triggers DNS propagation, so resolvers serve the old address until caches expire. Latchkey runners retry transient resolution failures during a cutover so brief inconsistency does not fail a deploy verification.
Key takeaways
- An A record maps a hostname to an IPv4 address, with AAAA for IPv6.
- A records can sit at the apex, unlike CNAMEs.
- Pinning an IP breaks if it rotates, so changes are subject to propagation.