DNS Propagation Checker

When you change a record at your DNS provider, the authoritative nameservers update almost instantly. But the resolvers operated by ISPs, public DNS services (Google 8.8.8.8, Cloudflare 1.1.1.1, OpenDNS), and corporate networks have already cached the previous value. They will continue to serve the cached answer until the record's TTL expires. A record with a 3,600-second TTL can take up to an hour to fully propagate; a record with an 86,400-second TTL can take a full day.

Some resolvers, particularly at ISPs and large corporate networks, ignore the TTL and cache answers longer than they should. This is why a change can be visible in Tokyo within minutes but still stale at a regional US ISP six hours later.

A propagation check shows the same query run against many resolvers at once. If every resolver returns the new IP, propagation is effectively complete for the public internet. If some still return the old IP and others return the new one, the change is partially propagated — wait for the original TTL to elapse before assuming a failure. If every resolver returns the old IP, the change hasn't reached the authoritative nameservers yet; verify it was saved correctly at your registrar.

Be aware that anycast networks (Cloudflare, Google Public DNS) may appear to flip back and forth between answers in the same check. This is expected — different anycast nodes have independent caches.

The single most effective trick is to lower the TTL 24–48 hours before a planned change. Drop it from 86,400 (one day) to 300 (five minutes), wait for the old long TTL to expire, then make the change. New records will propagate within minutes. After the cutover is stable, raise the TTL back to a sensible value (3,600–86,400 seconds) to reduce query volume on your nameservers.