Subject: [Enum] Standard DNS Delegation or CNAME/DNAME Redirection

From: "Robert H. Walter" <[email-masked]>
Date: Tue, 31 Oct 2000 12:56:57 -0500

Greg, Ann,

Please clarify why you believe CNAME and DNAME resource records
are required to redirect the DNS query from the designated
authority to the service registrar?  Why re-issue, reform the
query when standard DNS delegation will suffice? Consider the
following scenarios that assume the designated authority for
1.e164.arpa has provisioned the fully specified E.164 domain
name 2.1.2.1.5.5.5.0.0.8.1.e164.arpa on behalf of the service
registrar ACME:

Scenario 1: Use NS and A glue records to delegate authority for
the fully specified E.164 domain name to the registered name
server.  This approach has the advantage of not requiring client
resolvers and/or foreign name servers to additionally query for
the A records associated with the defined name servers.  Using
glue records has the additional restriction that the delegated
name servers MUST be children of the 1.e164.arpa sub-domain,
but results in reduced resolution time because there are fewer
queries and network traversals required.  Notice the extended
domain names for acmes name servers.

  2.1.2.1.5.5.5.0.0.8.1.e164.arpa. IN NS ns1.acme.1.e164.arpa.
                                   IN NS ns2.acme.1.e164.arpa.

  ns1.acme.1.e164.arpa.            IN A  192.249.249.1
  ns2.acme.1.e164.arpa.            IN A  192.249.249.2

Scenario 2: Use only NS records to delegate authority for the
fully specified E.164 domain name to the registered name server.
This approach has the disadvantage of requiring client resolvers
and/or foreign name servers to additionally query for the A
records associated with the defined name servers.  By not using
glue records, the delegated name servers are not required to be
children of the 1.e164.arpa sub-domain. The result is increased
resolution time due to additional queries and network traversals.

  2.1.2.1.5.5.5.0.0.8.1.e164.arpa. IN NS ns1.acme.com.
                                   IN NS ns2.acme.com.

In either scenario, the delegated name server must be minimally
provisioned with an e164.arpa zone that contains the associated
NAPTR records.  It may be more conventional that the delegated
name server be provisioned with the zone at the cut boundary
(1.e164.arpa), but this is not a requirement. Are you attempting
to avoid having the service registrar provision the e164.arpa
zone on their name server?

Bob

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