1 hour subdomain failures

[John Studarus]

	I've been tracking down a intermittent
name server problem from a single caching DNS server.
This caching DNS server will oscilate between
being able to answer queries and not being able
to answer the queries for hostnames in the subdomain.
The oscillations are exactly two hours in total
length (one hour it works, for the next hour
it is broken).
	When I say it is broken I mean that when
we send a query we never get a packet in reply.
When I perform the query via tcp the socket closes
right after the query.  (I've been modifying the
code to dnsquery for these tests).
	We have been monitoring several caching
name servers and this is the only server that has
this problem!
	Some more details...  The ttl for the NS
record for this subdomain is 1 hour.  The ttl for
hosts in this subdomain is 6 minutes.
	Could it be that when the NS record
expires (after 1 hour) the caching server waits
for an hour before it contacts the authoritative server 
again?  Does anyone know of a name server implementation
the exhibits this behavior?  (i.e. a 2 hour limit
before recontacting an authoritative name server?)

		-John

-- 
John Studarus <studarus at one.net>