An A record maps a hostname to an IPv4 address. It is the most common DNS record and the one browsers rely on to reach a website.
When you point a domain at a server, you create an A record that stores the server's IPv4 address, for example 192.0.2.10. Every time someone visits your site, their resolver asks the authoritative name server for the A record and connects to the address it returns. Because resolvers around the world cache answers for the length of the record's TTL, a change you make can appear instantly in one country and still show the old address in another.
This checker queries the A record for your domain from roughly twenty geographic vantage points and several public resolvers at once, so you can see the propagation in progress rather than guessing. If most locations already return the new IPv4 address and only a few lag behind, propagation is nearly complete. If the results are split evenly, you are in the middle of the TTL window and should wait. Lowering the TTL before a planned migration makes future A record changes propagate faster.
Frequently asked questions
- What is a good TTL for an A record?
- 300 to 3600 seconds is common. Lower it a day before a planned IP change so resolvers pick up the new value quickly.
- Why do some locations still show the old IP?
- Those resolvers cached the previous A record and will keep serving it until the TTL expires.