zone files for subdomains...

[Barry Margolin]

In article <bksodr$hk2$1 at sf1.isc.org>, Jim Reid  <jim at rfc1035.com> wrote:
>>>>>> "Barry" == Barry Margolin <barry.margolin at level3.com> writes:
>
>    >> True, but unless someone knows in advance what zones that
>    >> server has, there is no way of finding such an "unlinked"
>    >> zone. It can't be found by traversing a chain of NS records
>    >> from the root. So that zone will be like bigfoot or the Loch
>    >> Ness Monster: it might "exist" but nobody's been able to find
>    >> it. Debating the existence of these unlinked zones is a bit
>    >> like asking if a tree makes a sound when it falls down if
>    >> nobody is there to hear it.
>
>    Barry> Aren't we talking about a server that's authoritative for
>    Barry> both domain.com and sub.domain.com? 
>
>No, I don't believe so. IIRC the OP said that this was how things used
>to be set up. His/her clueless ISP didn't do the delegation properly.
>They got away with that because of an implementation fluke. Then the
>delegated zone got moved and promptly disappeared from the DNS because
>it had a broken delegation, prokoving the posting to bind-users.

I just reread the original posting, and I'm pretty sure I'm right.  He made
no mention of delegation from an ISP.

He said he's converting from a Cobalt Raq server to a DirectAdmin server,
and the latter includes DNS configuration software.  When he tries to
create both a domain and a subdomain on the new server, it creates separate
zones for them.

Since they're on the same server, everything should work fine.  The
mechanism used to walk down the DNS hierarchy doesn't involve asking each
level's server for NS records explicitly.  You ask each level's server for
the record you're actually interested in; if it's authoritative for the
domain it gives you an answer, otherwise it gives you a referral for a
server further down in the hierarchy.  If a domain and subdomain are on the
same server, the delegation for the domain works effectively as a
delegation for the subdomain as well, since the server will answer.

-- 
Barry Margolin, barry.margolin at level3.com
Level(3), Woburn, MA
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