8.2 and multiple-cnames/rrset-order support

Mark_Andrews at isc.org Mark_Andrews at isc.org
Wed Jun 9 22:05:56 UTC 1999


	From the 8.2.1 change log.

	626.   [bug]           multiple CNAME support was broken.

	8.2.1 is in public BETA ftp://ftp.isc.org/isc/bind/src/testing/t4b/

	Mark

>   Has multiple-cname support changed between 8.1.x and 8.2?  I noticed 
> some strange errors on a sun workstation after upgrading our name 
> servers to 8.2 and then realized that our CNAME-based round robins were 
> no longer functioning the way they used to.  On Solaris, the problem 
> evidences itself as follows:
> 
> Jun 4 08:34:49 dogbert nscd[224]: gethostby*.getanswer: asked for 
> l4dnfp4-160169.domain.com", got "l4dnfp4-160168.domain.com"
> 
> Looking at our DNS table dump, I see:
> 
> $ORIGIN 168.160.10.in-addr.arpa.
> 7       604800  IN      PTR     l4dnfp4-160168.domain.com.        ;Cl=3
> 
> $ORIGIN 169.160.10.in-addr.arpa.
> 13       604800  IN      PTR     l4dnfp4-160169.domain.com.        ;Cl=3
> 
> l4dnfp4 604800  IN      CNAME   l4dnfp4-160168.hewitt.com.        ;Cl=2
>         604800  IN      CNAME   l4dnfp4-160169.hewitt.com.        ;Cl=2
> 
> Our options in /etc/named.conf are set to:
> 
> options {
>         directory "/usr/local/named";
>         named-xfer "/apps/bind/current/bin/named-xfer";
>         multiple-cnames yes;
>         pid-file "/etc/named.pid";
>         use-id-pool yes;
>         rrset-order { order cyclic ; };
>         };
> 
> Doing a little further digging (pun, no-pun, whatever :-), I verified that
> the same A record was returned regardless of the first CNAME:
> 
>    QUESTIONS:
>         l4dnfp4.domain.com, type = A, class = IN
>     ANSWERS:
>     ->  l4dnfp4.domain.com
>         canonical name = l4dnfp4-160169.domain.com
>         ttl = 604800 (7 days)
>     ->  l4dnfp4.hewitt.com
>         canonical name = l4dnfp4-160168.domain.com
>         ttl = 604800 (7 days)
>     ->  l4dnfp4-160168.domain.com
>         internet address = 10.160.168.7
>         ttl = 604800 (7 days)
> 
>    Is this the (new) expected behavior under 8.2?  I was basing my 
> expectations on the doc, which states:
> 
> multiple-cnames 
> If yes, then multiple CNAME resource records will be allowed for a 
> domain name. The default is no. Allowing multiple CNAME records is 
> against standards and is not recommended. Multiple CNAME support is 
> available because previous versions of BIND allowed multiple CNAME 
> records, and these records have been used for load balancing by a 
> number of sites. 
> 
>    Thanks.
> 
>    Erick.
> 
> 
> 
> 
> _______________________________________________________
> Get your free, private email at http://mail.excite.com/
> 
> 
--
Mark Andrews, Internet Software Consortium
1 Seymour St., Dundas Valley, NSW 2117, Australia
PHONE: +61 2 9871 4742                 INTERNET: marka at isc.org



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