TTL Question

Mark Andrews Mark_Andrews at
Tue Oct 16 22:31:16 UTC 2007

> What dictates how long another name server caches the authoritative name 
> server for a domain? I was under the impression it was the default 
> time-to-live, but I have a situation where an authoritative name server 
> was removed from service several days ago, yet queries to it continue. Dig 
> is correctly reporting the new authoritative name servers for the domain 
> in question. How common is it for DNS servers to ignore the ttl?

	Because you failed to update *ALL* the servers for the zone to
	have the new content.  Every time a cache queries the old servers
	it re-learns the old NS RRset for the zone.

> -Mike
Mark Andrews, ISC
1 Seymour St., Dundas Valley, NSW 2117, Australia
PHONE: +61 2 9871 4742                 INTERNET: Mark_Andrews at

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