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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