A
Address Record (IPv4)
An A record maps a hostname to an IPv4 address. Learn how A records relate to mail servers, SPF, and FCrDNS checks.
Published · Last verified · Maintained by TamingDNS
A
Address & Routing
RFC 1035
Yes
A <ipv4-address>
A 93.184.216.34
3600 s typical; 300 s during migrations or failover testing
💬 What This Record Does
An A record is the simplest DNS record: it maps a hostname to an IPv4 address. When your browser or mail server needs to connect to example.com, it queries the A record to find the IP address. For email, A records are used by MX hosts (your mail server's hostname must have an A record), by the SPF "a" mechanism (which authorises the IP in an A record), and by FCrDNS checks (the PTR hostname must resolve forward via an A record back to the sending IP).
Common Uses
- Resolving your mail server hostname to an IP for MX routing
- Being referenced by the SPF "a" mechanism
- The forward lookup half of an FCrDNS (PTR ↔ A) check
⚠️ Watch Out For
- MX records must point to hostnames, not bare IPs. The hostname needs an A record.
- If your A record changes and SPF uses the "a" mechanism, your SPF authorised set changes silently.
🔧 Related Tools
📋 Complete Example Records
Whole records in zone-file form: name, TTL, class, type, then the data. Most DNS panels ask for the pieces separately. Look them up live with the DNS Lookup tool.
mail.example.com. 3600 IN A 192.0.2.10
A mail server's address record. Every hostname an MX record points at needs one, or delivery has nowhere to go.
example.com. 3600 IN A 192.0.2.10 www.example.com. 3600 IN A 192.0.2.10
The apex and www pointing at the same address. The apex cannot be a CNAME, so it takes an A record even when www does not.
example.com. 3600 IN A 192.0.2.10 example.com. 3600 IN A 192.0.2.11
Two addresses on one name, which resolvers hand out in varying order. Bear in mind the SPF "a" mechanism authorises both.
mail.example.com. 300 IN A 192.0.2.10
The same record with a five-minute TTL, dropped ahead of a migration. Lower it a day before the move so caches have expired by the time you cut over.