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What is the correct behaviour when Nameservers Change

I registered a domain at GoDaddy and changed the nameservers to my server's. (GoDaddy sets up the domain using their own nameservers initially.) Now, almost 24 hours later, how come when using some ISPs you get forwarded to my nameservers, whereis for some it still is the old entry? I guess there is some form of caching involved.

Is there some way to know when all users will be routed to my nameservers? And more generally, how can I learn more about the underlying principles?

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marked as duplicate by Alnitak, Chris S, MDMarra, John Gardeniers, Jeff Ferland Dec 6 '12 at 16:44

This question has been asked before and already has an answer. If those answers do not fully address your question, please ask a new question.

This doesn't answer your question, but it can help you research the affects. Take a look at (shameless plug, I made the tool). It will perform the DNS lookup on your domain from a lot of different places, and help you get a feel for how the propagation is going. – preinheimer Nov 15 '11 at 22:21
@preinheimer great tool and contribution! Cheers – iainlbc Nov 15 '11 at 23:04
thanks! It seems just my ISP is caching the old version. Probably because I requested the page before I made the switch. – Michael Nov 15 '11 at 23:24

Now, almost 24 hours later, how come when using some ISPs you get forwarded to my nameservers, whereis for some it still is the old entry?

You must know 2 things:

  • DNS records have TTL (TimeToLive), which define timeslot for lifecycle
  • Intermediate DNS during resolving store received results in internal cache and will answer with this data instead of re-requesting (during TTL of RR or while server reload not happens)

With 1+2 we'll get: for servers, which had your old data, it will be used while not outdated according to TTL, not current state; who hadn't old data before - now get data from new location. Before any DNS-restructuring in the form of changing existing data, best method is decrease TTL to minimum (for zone or some RR), wait for expiration of all data with old (long) TTL, after it change RR-values

PS - there are also some RFC-ignorant operators, which use old data even after TTL-expiration, but you can do nothing with such behavior.

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Thank you for the very helpful response. (P.S. a Cyrillic character managed to sneak into your post. "шт еру" :)) – Michael Nov 15 '11 at 23:28
"in the" fixed :-) – Lazy Badger Nov 15 '11 at 23:33

The only way to guarantee that everyone starts using your new nameservers, is to make sure the old nameservers also contain the new information, including the new NS records.

For more details see my answer to this question which describes why some DNS clients keep talking to the old nameservers even when the parent zone NS records have changed.

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