How many NS records should be in the 0.0.127.in-addr.arpa zone?

[Bill Larson]

> > > According to the DNS and BIND book the zone file for 0.0.127.in-addr.arpa
> > > should contain an NS record for each server in your domain (see the 3rd
> > > edition page 67).  First question - is this a correct assumption?
> > 
> > This doesn't seem correct.  I don't have my copy of DNS & BIND handy
> > so I can't check your reference.
> 
> D&B does NOT say that.  It gives an example, in which there are two (2)
> NS records instead of 1.  It makes no statement why it does so, or
> whether you should use 1 or 2 or N, N > 2.
> 
> I realized today why that might be.  Some systems start other network
> aware programs before 'named'!  ;-?  If they cannot reach their own
> local 'named', they might be able to reach the other one.
> 
> Maybe I'll change mine to point to two servers, now.  ;-}

I'm confused as to why having more than one NS record for the
0.0.127.in-addr.arpa zone would be useful.

If every name server is a master for this 0.0.127.in-addr.arpa zone,
then a query of this zone send to ANY server would always return an
authoritative answer.  A server can ONLY respond authoritatively to
a query if the server is identified with an NS record as being
authoritative for the zone.

Now, as to the point of the system starting network applications prior
to starting named, if named isn't running then named cannot return ANY
answer - including identifying a second name server to query for a
zone.  This is an issue that can only be resolved by the use of
resolv.conf identifying more than one name server and having a
non-local named supply this DNS information, or possibly using an
nsswitch.conf type file directing the gethostby* library routines to
use /etc/hosts, DNS, and/or NIS for resolving DNS type queries.

Again, for what purpose would having more than one NS record be for the
0.0.127.in-addr.arpa zone?  I will hold to identifying ONLY a single
server for this zone.  This would also avoid the problem with NOTIFY
packets for the zone which started the whole thread (as identified by
Jim Reid's posting).

Bill Larson (wllarso at swcp.com)