strange zones in named.conf

Question

I have inherited some servers and I am trying to understand/improve the named.conf and zone files, I have bought the O'reilly dns and bind book. The server has some zones that aren't mentioned in the book, but the names suggest to me that they are related to standard internal processes :

zone "localdomain." IN {
type master;
file "localdomain.zone";
allow-update { none; };
};

zone "localhost." IN {
type master;
file "localhost.zone";
allow-update { none; };
};

zone "255.in-addr.arpa." IN {
type master;
file "named.broadcast";
allow-update { none; };
};

zone "0.in-addr.arpa." IN {
type master;
file "named.zero";
allow-update { none; };
};

Any thoughts as to whether these are required?

The server is running RHEL 5.

Answer 1

These entries/zones are required by RFC 1034 and represent the DNS entries for localhost and their PTR records. They are only for IPv4 and you have to add the entries/zones for IPv6 if you want to resolve AAAA records for names and their rDNS entries.