An A record maps a hostname to an IPv4 address. It is the most common DNS record used to point websites and APIs to servers, CDNs, or load balancers. If a site is down or pointing to the wrong system, the A record is the first place to check.
When a resolver looks up example.com, it returns the IPv4 address from the A record. The apex and www can be configured differently, so verify both if you expect them to match. For IPv6, you also need an AAAA record and the corresponding IPv6 address.
Use the A record lookup tool to query multiple resolvers and compare results. If you suspect propagation issues, run a DNS propagation check and compare with the authoritative name servers listed in the NS record guide.
A records often work alongside CNAME for aliases, AAAA for IPv6, and PTR for reverse DNS.