traffic

[Joseph S D Yao]

On Sat, Feb 08, 2003 at 03:32:06AM +0000, fringet1 wrote:
> Ok, I have been reading Oreilly's DNS and Bind 4th Ed.  Learning a bunch and
> pondering.  One theought that came to mind, mind I am not a network
> engineer, is say I do host a domain, use an internal name server for that
> domain and internal resolution, when I query that name server when I go to a
> site is all return traffic for that request then rerouted back through that
> same machine???

Pronoun disease.  Not sure what you are talking about: "that" request,
"that" machine.  Let's go through a scenario.

DNS client	Local DNS server		Domain's DNS server

Query	->	receives query, no cache
		looks up "who is domain server"
		eventually ...
		Query			->	receives query
		receives response	<-	response
		caches response
receives   <-	response
response

another	->	receives query, cached
query
receives   <-	response
response

As you can see, the "DNS client" on your typical machine has only a
stub resolver.  It is compelled to ask a small set of local DNS servers
any queries that it might have.  The local server, if it doesn't have
the answer cached, has to go out and find the appropriate name server.
It then asks the appropriate name server, and receives the appropriate
answer.  It returns this answer to the original querier, but also
caches it for an amount of time under the remote domain's name server's
control, in case it gets asked again some time real soon now.

Hope this helps!

-- 
Joe Yao				jsdy at center.osis.gov - Joseph S. D. Yao
OSIS Center Systems Support					EMT-B
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