prereq yxrrset problem

[Mark.Andrews at nominum.com]

> 
> I've noticed a problem with dynamic updates when using an "RRset
> exists (value dependent)" prerequisite and more than one record
> of the specified type exists.  Perhaps somebody can tell me if
> I'm missing something or if BIND is behaving strangely.
> 
> Here's an example that works:
> 
> 1. The zone example.com has no MX records.  Add one MX record
> by feeding the following to nsupdate:
> 
>   update add example.com. 3600 IN MX 10 mail1.example.com.
> 
> 2. Delete the MX record with the following:
> 
>   prereq yxrrset example.com. IN MX 10 mail1.example.com.
>   update delete  example.com. IN MX 10 mail1.example.com.
> 
> 3. This update returns NOERROR and the record is deleted.
> 
> Here's an example that fails:
> 
> 1. The zone example.com has no MX records.  Add two MX records
> with the following:
> 
>   update add example.com. 3600 IN MX 10 mail1.example.com.
>   update add example.com. 3600 IN MX 10 mail2.example.com.
> 
> 2. Issue the same delete command as in the previous example:
> 
>   prereq yxrrset example.com. IN MX 10 mail1.example.com.
>   update delete  example.com. IN MX 10 mail1.example.com.
> 
> 3. This update returns NXRRSET and no record is deleted.  The
> nameserver (8.2.3-REL) logs the following:
> 
>   error processing update packet (NXRRSET) id 34346 from [10.0.0.1].3666
> 
> A correspondant reports the same behavior with 9.1.1rc6.  We
> can work around the problem by omitting the prerequisite, but
> sometimes a prerequisite can be handy and it ought to work as
> far as I know.
> 
> Am I missing something?  I've been looking through RFC 2136 but
> nothing has jumped out at me yet.

	prereq yxrrset example.com. IN MX 10 mail1.example.com
	prereq yxrrset example.com. IN MX 10 mail2.example.com

	would have caused the failing example to succeed.

	The whole RRset has to match, not just individual RRs.

	Mark
> 
> Thanks.
> 
> -- 
> Michael Fuhr
> http://www.fuhr.org/~mfuhr/
> 
--
Mark Andrews, Nominum Inc.
1 Seymour St., Dundas Valley, NSW 2117, Australia
PHONE: +61 2 9871 4742                 INTERNET: Mark.Andrews at nominum.com