new records

[Mark_Andrews at isc.org]

> If a domain is already cached in the user's lookup DNS and a new record eg.
> "A" type is added,  does the TTL have to expire or does the user's lookup
> DNS server determine it has not got that new record in cache and immediately
> goes to the authoritative server to retrieve the new record to satisfy the
> user's request?
> John at Aylmer.com.au

	You don't cache domains (except for NXDOMAIN) even then it
	is for a particular class.   You cache <domain,type,class>
	tuples.

	If you already have <domain,type,class> then it will be
	answered from the cache.  If you don't have <domain,type,class>
	the nameserver will go out and get the answer.  Note a cached
	negative response to <domain,ANY,class> will match more specific
	types.

	Mark
--
Mark Andrews, Internet Software Consortium
1 Seymour St., Dundas Valley, NSW 2117, Australia
PHONE: +61 2 9871 4742                 INTERNET: Mark.Andrews at isc.org