Re: [DNSOP] simple question

[Havard Eidnes <[e-mail]>]

> consider a nameserver ns.example.com serving example.com. There is a
> delegation from com. including glue.
> Now we add a childzone sub.example.com. served by the same nameserver
> ns.example.com.
>
> should I add a entry in example.com to delegate the subzone to myself?

Generally, yes, although with the specific example, your name
server software may let you get away with not having the NS
record in the example.com zone for sub.example.com.

However, think more generally: if example.com is served by one
set of name servers, and there are some of them which do not
serve the sub.example.com zone, and you have no NS records for
sub.example.com in the parent zone, you've just created breakage,
because those which don't serve sub.example.com will return
NXDOMAIN when queried for names in that zone.

The general rule is therefore: to delegate a zone, you copy the
NS RRset from the child zone into the parent zone.  If you follow
this rule always you won't get into the above problem.

Regards,

- Håvard