Delegation question

[Stephane Bortzmeyer]

On Fri, Feb 04, 2011 at 09:55:07PM +1100,
 Jean-Yves Avenard <jyavenard at gmail.com> wrote 
 a message of 112 lines which said:

> Now if I uncomment the NS ad.domain.com. mel.domain.com will not
> resolve anymore:

General rule with Unix daemons: always read the log. You'll find the
error message.

BIND-specific rule: test your zone with named-checkzone.

Here, I suggest you will get a "Out of zone data" error (once there is
a delegation, the A record for the same name is probably a mistake).