TYPE=ANY and missing records

[Barry Margolin]

In article <812q76$36d$1 at nnrp1.deja.com>,  <greg_mcdermid at my-deja.com> wrote:
>Problem is that any requests with TYPE=ANY seem
>to only return the NS records - which is not good
>as sendmail only requests ANY, then A (most
>domains don't have an A record for their domain),
>thus the mail simply queues up.

If you're querying a caching server, an ANY query will return whatever
happens to be in the cache for the name.  If the NS records are already in
the cache (because you've looked up something within the domain), they'll
be returned.  The caching server can't tell whether its information is
complete without performing another recursive query, so the alternative
would be for all ANY queries to force recursion, rather than using the
cache, which would not be good.

Applications should generally *not* use ANY queries unless they know for a
fact that they're querying an authoritative server rather than a caching
server (i.e. they implement their own full resolver, rather than using a
stub resolver).

-- 
Barry Margolin, barmar at bbnplanet.com
GTE Internetworking, Powered by BBN, Burlington, MA
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