subdomain dns question

[Barry Margolin]

In article <37b3001c.406697188 at news.cncdsl.com>,
High Mercury <merc at sabatini.org> wrote:
>I have the following situation.  We want to seperate network2 from
>network1 and let it have it's own internet connection while still
>allowing access to network1and also not have to change the domain
>structure.  The problem is network2 currently is primary for the zone
>y.x.com.  It is importat for mail going to network2 to travel through
>isp2 and then to network2 directly rather than needing to query the
>external dns for x.com first.  The only way i see of doing this is by
>getting another domain name for network2 but this is somewhat
>undesirable. Does anyone know a way to pull this off without using
>another domain name instead of y.x.com?

You seem to be confusing a number of things.  What does it mean for a
network to be primary for a zone?  DNS servers are primary/secondary for
zones, networks aren't.  I guess you mean that the primary server for
y.x.com is on network2.  Furthermore, the path that mail takes has nothing
to do with the location of the DNS servers.

I don't know of any way to make DNS queries for the y.x.com domain succeed
without first querying the server for x.com.  DNS is hierarchical, and you
have to work your way down the hierarchy incrementally.  The server for
..com only knows the servers for x.com, it can't provide referrals directly
to the y.x.com servers.  However, once a remote server has been given the
y.x.com referral, it will cache this, and future queries will go directly
to that server without going through the x.com server (until the cached
NS record times out).

So, although the DNS queries will occasionally go through the x.com server,
mail will be sent directly to the y.x.com mail server.

-- 
Barry Margolin, barmar at bbnplanet.com
GTE Internetworking, Powered by BBN, Burlington, MA
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