SharkDNS guide
5 min readDNS propagation check explained
Why DNS changes take time to appear, how caches and TTLs work, and how to verify propagation across regions.
DNS propagation checkerglobal DNS checkTTL cacheDNS传播检测
When to use it
Run a propagation check right after changing a record: moving hosts, switching mail providers, updating nameservers, or rotating TLS-related records.
Why answers differ across regions
Recursive resolvers cache records for the duration of the TTL. A resolver that cached the old answer five minutes ago keeps serving it until the TTL expires, while a resolver with an empty cache fetches the new answer immediately.
How to speed up propagation
Lower the TTL well before a planned change, wait one old TTL cycle, make the change, then raise the TTL again. A propagation checker confirms when every region serves the new answer.
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