Why a DNS change does not apply everywhere at once
Resolvers remember answers for as long as the record's TTL allows. If you change an A record with a TTL of 86400, resolvers that saw it yesterday serve the old value for up to 24 hours – each resolver on its own, depending on when it last asked. That is why a visitor in Berlin already sees the new site while one in Munich still sees the old one. "Propagation" is not distribution, it is caches expiring.
How to read the result
- At the top is the state of the authoritative name servers – the target. If it still returns the old value, the zone has not been reloaded or the change was not saved at the hoster.
- "current": the resolver returns exactly the authoritative state. "still stale": it holds a different value in its cache, which expires with the old TTL.
- "no answer": the resolver was unreachable or exceeded the time budget – no verdict.
- A single anycast resolver such as 8.8.8.8 answers from many data centres; our request hits one of them. That another location of the same provider is still stale cannot be ruled out this way.
Before a migration: lower the TTL
Set the TTL of the affected records to 300 seconds one or two days before the change. Then caches expire within five minutes after the switch instead of producing mixed states for a day. Afterwards you can raise the TTL again. DomainWarn monitors DNS records continuously and reports every change – including the ones you did not make yourself.
Frequently asked questions
How long does DNS propagation take?
As long as the TTL of the old record, usually between five minutes and 24 hours. A name server change (NS records) can take up to 48 hours because registry caches have to expire too.
All resolvers are current but I still see the old site – why?
Your computer, router or browser keeps its own cache. Flush the DNS cache, restart the browser or try another network. With HTTPS sites an HSTS or service worker cache can also show the old page.
Can I speed up propagation?
Not after the change – caches expire by their TTL. Beforehand: lower the TTL. Large resolvers (Google, Cloudflare) offer forms to purge individual names.
What does the tool check for MX, TXT and NS?
The same principle: the value at the authoritative name servers against the cache state of the resolvers. For TXT (SPF, DMARC, verification codes) all TXT records of the name are compared.