Recursive DNS problem

Joseph S D Yao jsdy at
Sun Jan 30 00:11:21 UTC 2011

On Fri, Jan 28, 2011 at 10:52:42AM +0800, bangla desh wrote:
> I am wondering, is there a dns rule/standard (or RFC) that explains about
> delegation?

Here are some simple rules for DNS delegation.  [If I have
oversimplified, the generous souls on this mailing list will let me

(1) All publicly available authoritative name servers for a zone on the
same internet MUST serve identical copies of the domain.  [Split DNS is
excepted, I think, by the modifiers.]

(2) Not all authoritative name servers must be listed in NS records in
the zone, but enough should be that the zone is available whenever any
members of the zone are available.  [This is not a technical
requirement, it is merely prudent.]

(3) The list of name servers (NS records) in the delegating (parent)
zone MUST be identical to the list of name servers in the zone itself.

(4) The delegating (parent) zone MUST have "glue" A records for any name
server names that are in that zone itself or any "descendant" zones, but
MUST NOT for any non-descendant name server names.  For example: zone
"" is delegating "".  The name servers are
"", "", "", and
"".  The first one would have an A record in the
delegating zone anyway.  The second two MUST have "glue" A records
because they both are in "descendant" zones.  The last MUST NOT have a
glue "A" record because it is NOT a descendant.

(5) Any changes in the name servers of the delegated zone MUST be
communicated freely between delegator and delegatee before the change,
with a mutually agreed-on time to make the change (and using decreased
TTLs etc. as usual with such a change).

** Joe Yao				jsdy at - Joseph S. D. Yao

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