DNS Propagation
Compare what several public resolvers return for a record right now.
What this tool measures
It queries several independent public resolvers for the same record and shows their answers side by side. When they agree, the change has reached those resolvers. When they disagree, at least one is still serving a cached copy.
This is a comparison of resolvers, not a worldwide survey. Large resolvers run anycast networks with independent caches per location, so agreement here is strong evidence rather than proof that every resolver on the internet has caught up.
Why propagation takes time
"Propagation" is really cache expiry. When you change a record, resolvers that already have the old value keep serving it until its TTL runs out. Nothing pushes the change to them.
That means the practical wait is bounded by the TTL that was in effect *before* the change, not the one you set afterwards. Lowering a TTL a day ahead of a planned migration is what makes the cutover fast.
When results stay inconsistent
Persistent disagreement long after the TTL has passed usually points at the authoritative side rather than caching — nameservers that are out of sync with each other, or a registrar delegation still pointing at an old provider.
Checking the domain’s NS records tells you which nameservers are actually authoritative, which is the right place to start.