Resolving Internet names: Actually call root servers?

[Mark.Andrews at nominum.com]

	Time for DNS 101.

	The DNS is a distributed, replicated, heirarchical database.
	The root servers server the top of the heirarchy.  They
	refer querying resolver to other server, which may inturn
	refer the querying resolver to others which are deeper in
	the heirarchy.  This repeats until you reach a server has
	the answer.

	Quering resolvers generally cache the responses received
	and use the cached information to optimise the next query.

	When looking up host.example.com the query first goes to
	the root servers, which refer to the com server, which
	inturn refer to the example.com servers which will answer
	the query.  Now if the same resolver attempts to lookup
	foo.example2.com, it will start with the com servers which
	will refer it to the example2.com server which should be
	able to answer the query.

	Resolver here refers to a full service resolver.  Stub
	resolvers, found in most machines, just forward the query
	to a nameserver which contains a full service resolver
	which does the work for it then returns the answer.

	This is explained in RFC 1034, DOMAIN NAMES - CONCEPTS AND
	FACILITIES.

	Mark

> Hi,
> 
> I was wondering if DNS servers actually call root servers when they
> need to resolve Internet host names, or are queries silently delegated
> to lower-level servers to avoid swamping those few root servers in
> name.ca?
> 
> Thx
> FF.
> 
> 
--
Mark Andrews, Nominum Inc.
1 Seymour St., Dundas Valley, NSW 2117, Australia
PHONE: +61 2 9871 4742                 INTERNET: Mark.Andrews at nominum.com