Problems accessing the root servers

[srp336 at my-deja.com]

I'm trying to track down some performance problems on our network. I've
noticed  that I sometimes have some trouble querying some of the root
name servers, a.root-servers.net, and h.root-servers.net in particular.
Sometimes, the response will be instantaneous, sometimes, it will come
after a several second delay, and sometimes, I'll get "no response from
server." I've been thinking that this would cause intermittent problems
for our users, based on two assumptions [which I'd like to verify as to
whether they are right]:

(1) The name severs for some of the major top level domains are on the
same hosts as the root name servers. I thought I had read that
somewhere, but I'm not sure now. Is there an RFC explaining how the
root servers and TLD servers are set up?

(2) The way I understand DNS resolution is: each time a query needs to
be made, a different server from the list of all available
authoritative servers are used until a round-trip time is available for
each of them. After which, the servers with the best times are used,
and occasionally, some of the servers with the worst times are tried
again. If the response time we are getting from some of the root
servers is constantly poor, they would hardly ever get used by our
resolvers, but since it's only sometimes problematic, I would assume
that problematic servers would be getting used more often then they
should.

I realize that I may be confused here, and I might be way off-track.
But so far, everything I've tried to figure out this network
performance problem has turned out to be nothing.

If I'm even close to an idea, what might I be doing wrong, or blocking
that I shouldn't be. I assume that the problem is probably on my end,
since no one else seems to be dealing with this problem.

Thanks,

--Steve


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