zone and sub-zone

[Kevin Darcy]

Robert Story wrote:

>On Thu, 19 Jan 2006 09:54:59 -0500 Frank wrote:
>FYFL> But, for example:
>FYFL> 
>FYFL> host A hosts both domain xyz.org and sub-domain abc.xyz.org as master
>FYFL> 
>FYFL> host B only hosts domain xyz.org as slave, no sub-domain abc.xyz.org defined
>FYFL> 
>FYFL> Say a client looks up against host B for a host name 123.abc.xyz.org in
>FYFL> sub-domain. Since host B is also authoritative for xyz.org (but not
>FYFL> abc.xyz.org), will host B reply as NXDOMAIN or will go to host A find out
>FYFL> and return the right resolution?
>
>That depends on whether or not host B has recursion enabled. If it
>does, it should go to host A to find the data. If not it will return
>the nameservers for abc.xyz.org (presumably host A).
>
A couple little elaborations/clarifications:

1. host B would have to have recursion enabled and the client would have 
also had to have requested recursion. Iterative resolvers should never 
recurse unless the client asks them to.

2. the referral will be returned, or the recursion will be performed, 
*if*the*subzone*is*delegated*, otherwise NXDOMAIN is returned. Although 
it is not recommended practice, technically, one can have an undelegated 
zone, which is known only to the servers specifically configured for it, 
and is not findable through regular iterative resolution.

- Kevin