8.2 and multiple-cnames/rrset-order support

T. Esting t_esting at excite.com
Tue Jun 8 23:09:38 UTC 1999


  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.




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