query for domain, where does this server get the answer from ?

[Kevin Darcy]

ymj at ifrance.com wrote:

> When I query a DNS server (with nslookup for example) for
> NS records of e.g mydomain.com i receive a list of DNS servers.
> So far so good.
> But the DNS server I'm querying only has information about
> i.e:  aaa.mydomain.com , bbb.mydomain.com and ccc.mydomain.com
>
> It has no forwarders set up.
>
> So where does it get this information from ?
> Root servers ?
> NO! i dont think so because the list of NS records for mydomain.com is
> NOT the same compared to the one given by the Root.......

The DNS namespace is hierarchical. If you ask the root nameservers about
aaa.mydomain.com they may only give you back a referral to the "com"
servers; you then ask the "com" servers and they may only give you back a
referral to the "domain.com" servers. Note that because of caching, you
normally don't go through all of those steps: if you already know the
nameservers for "domain.com", then you can ask them questions directly
without having to ask any other nameservers.


- Kevin