DNS Propagation Check
Query the same record at multiple public resolvers at once and compare the answers - the fastest way to see whether a DNS change has landed everywhere.
Result
About DNS Propagation Check
"Propagation" is really just cache expiry. When you change a record, every resolver keeps serving the old value until the TTL it received counts down to zero. This tool asks several independent public resolvers at once so you can see who has caught up.
What to do before a change
Lower the TTL on the record before the change - to 300 seconds, at least one full old-TTL period ahead. Once the change is complete and verified, raise it again. Cutting the TTL at the same moment you change the value does nothing: resolvers are already holding the old record with the old TTL.
When resolvers disagree
If two resolvers still disagree long after the TTL has expired, the problem is not caching. Check that every authoritative nameserver returns the same SOA serial - a stale secondary that stopped transferring the zone will happily serve last month's records forever.
Common use cases
- Confirming a cutover before switching traffic or updating a firewall rule.
- Diagnosing "it works for me but not for them" reports after a DNS change.
- Verifying nameserver changes during a registrar or DNS provider migration.
Edge cases and gotchas
- This compares public recursive resolvers, not geographic vantage points. Corporate and ISP resolvers may lag further behind.
- A resolver may return a different answer legitimately if the zone uses geo-based or latency-based responses.