[Gllug] DNS

[Paul Brazier]

> No, the root servers are rarely involved.  When you resolve a domain
> name, you're talking to your ISP or network's nameserver, 
> which has got
> its information from a number of other nameservers, leading - at some
> point - back to the root servers.  This is why a DNS change 
> on a domain
> name will take some hours to propagate; it needs to make its way from
> the root servers all the way down to your local network.

So say I want to resolve some obscure domain that no-one using my ISP
has visited recently.
Would the query in this case go all the way down to the root server and
then up again to the authoritative domain that I'm resolving?

Does the number of nameservers queried along the chain match the number
of dots in the domain name (maybe plus or minus one or something)
(assuming it doesn't used a cached result)?

Surely the ISPs' nameservers must periodically query the root servers
even for sites like google just to check the IP address hasn't changed
since the last query. But they also cache the results for some pre-set
duration to avoid a lookup each time. Is this right?


**********************************************************************
This email and any files transmitted with it are confidential and
intended solely for the use of the individual or entity to whom they
are addressed. If you have received this email in error please notify
the originator.

This footnote also confirms that this email message has been checked
for the presence of computer viruses.

**********************************************************************


-- 
Gllug mailing list  -  Gllug at linux.co.uk
http://list.ftech.net/mailman/listinfo/gllug