Questions about "incomplete" additional data

Mark.Andrews at nominum.com Mark.Andrews at nominum.com
Tue Jul 25 00:11:16 UTC 2000


	Named will look up missing records whenever it has attempted
	to find them and failed except when sysquery calls sysquery
	and the later sysquery needs a sysquery.  

	So the answer to this particular question is "when it tries
	to add the additional record to the response".

	Mark

> 
> At the risk of displaying my ignorance of BIND internals, I have some
> questions about how BIND behaves when receiving an incomplete list of A
> records in the additional section of a referral.
> 
> For example, let's say that in the process of resolving www.foo.us/IN/A, a
> BIND server sends that query to a root name server and receives this
> referral:
> 
> ; Authority
> us.     in  ns  ns1.foo.us.
> us.     in  ns  ns2.foo.us.
> us.     in  ns  ns1.bar.net.
> 
> ; Additional
> ns1.foo.us. in  a   1.2.3.4
> ns2.foo.us. in  a   1.2.3.5
> 
> In other words, there's no A record for ns1.bar.net included in the
> additional section.  And this is a new enough server so that TC isn't set on
> this reply.  My questions are:
> 
> - When does a BIND server resolve ns1.bar.net/IN/A--immediately upon receipt
> of the referral, or does it wait until it actually needs to send a query to
> ns1.bar.net?
> 
> - Are the name servers whose A records are present in the additional section
> "favored" in any way?  For example, would ns1.foo.us and ns2.foo.us each
> receive more queries than ns1.bar.net?
> 
> - Is BIND's behavior in this situation consistent across all (most?)
> versions?  Do some versions of BIND have drastically different behavior than
> others in this regard?
> 
> Thanks to those who can read the source better than I for any insight.
> 
> Matt
> --
> Matt Larson <mlarson at netsol.com>
> Network Solutions Registry / www.nsiregistry.com
> 
> 
> 
> 
--
Mark Andrews, Nominum Inc.
1 Seymour St., Dundas Valley, NSW 2117, Australia
PHONE: +61 2 9871 4742                 INTERNET: Mark.Andrews at nominum.com



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