I don't understand this statement. For example, the vast majority of the 'com' zone are NS records for subdomains, and that is considered part of the com. zone.
The NS records themselves are within 'com' so they are part of the 'com' zone. It is the NS record itself that forms the delegation. The article elsewhere makes a mention of "someone else" but of course you can delegate to yourself. What makes a delegation is an NS record. What makes a zone is really an SOA record (and the corresponding sibling authoritative NS records in that zone).
Aside, I always found it somewhat interesting that the DNS RFCs go into the implementation details of BIND. It's not really relevant to the operation of a other DNS implementations what the syntax of a zone file should be. Or how replication (AXFR) should be handled. The SOA record itself contains information that only BIND even cares about.
Heh, I'm very familiar with DNS and the RFCs. I was questioning the wording of the statement. "A name and all the names below it that are not delegated to someone else is collectively called a zone". The names in the com zone are delegated to someone else, hence the NS records. Just murky wording to me, but maybe I'm reading it wrong.
The NS records themselves are within 'com' so they are part of the 'com' zone. It is the NS record itself that forms the delegation. The article elsewhere makes a mention of "someone else" but of course you can delegate to yourself. What makes a delegation is an NS record. What makes a zone is really an SOA record (and the corresponding sibling authoritative NS records in that zone).
FWIW, RFC 1034 and 1035 are very readable.
http://tools.ietf.org/html/rfc1034
http://tools.ietf.org/html/rfc1035
Aside, I always found it somewhat interesting that the DNS RFCs go into the implementation details of BIND. It's not really relevant to the operation of a other DNS implementations what the syntax of a zone file should be. Or how replication (AXFR) should be handled. The SOA record itself contains information that only BIND even cares about.