is NS record pointing to "some other name server" needed in case of classless IN-ADDR.ARPA delegations?

[Martin T]

Hi,

in case of classless IN-ADDR.ARPA
delegations(http://www.ietf.org/rfc/rfc2317.txt) I have usually seen
at least one NS record pointing to name server other than the
end-customer ones. Example from rfc2317.txt where there are two NS
records and the second one is not the end-customer name server:


;  <<0-127>> /25
0/25            NS      ns.A.domain.
0/25            NS      some.other.name.server.
;
1               CNAME   1.0/25.2.0.192.in-addr.arpa.
2               CNAME   2.0/25.2.0.192.in-addr.arpa.
3               CNAME   3.0/25.2.0.192.in-addr.arpa.
;


Another example from one real name server zone file:

;
0               IN      NS      ns.content-providerA.com.
0               IN      NS      ns2.content-providerA.com.
0               IN      NS      ns.isp-of-content-providerA.net.
;
1               IN      CNAME   1.0.47.168.192.in-addr.arpa.
2               IN      CNAME   2.0.47.168.192.in-addr.arpa.
3               IN      CNAME   3.0.47.168.192.in-addr.arpa.
;

Is NS record pointing to "some other name server" needed in case of
classless IN-ADDR.ARPA delegations? What happens if one does not
specify this?


regards,
Martin