How this check works
We find the zone’s authoritative name servers and query them directly, then send the same question to public resolvers: Cloudflare, Google, Quad9, OpenDNS and AdGuard DNS. Each query is sent once, without our cache.
The authoritative answer is the reference. A resolver with a different answer still holds a cached copy; its TTL tells you the longest it may keep it (RFC 1034, and RFC 2308 for “not found” answers).
Limitations
- Large resolvers run many caches behind one address, so two queries a minute apart can return different answers.
- We query at most four authoritative servers, and only at public addresses.
- Checked domains are not stored or logged.
Frequently asked questions
How long does DNS propagation take?
Up to the TTL of the old record in each resolver’s cache. If the record did not exist before, resolvers may cache the “not found” answer for the negative TTL taken from your zone’s SOA record.
Can I speed it up?
Lower the TTL a day before a planned change. Some public resolvers also let you purge a name from their cache through a web form.
Why do my name servers return different answers?
Secondary servers have not loaded the latest version of the zone yet, or the zone is edited in two places. Compare the SOA serial numbers in your DNS provider.
Which record types can I compare?
A, AAAA, MX, TXT, CNAME, NS and CAA.