"multiple RRs of singleon type""multiple RRs of singleon type"
Here is an example syslog error message we received on a BIND 9.x nameserver
when trying to perform a zone transfer from a master zone with "multiple RRs of
singleton type."
Mar 18 15:36:23 host named[748]: [ID 866145 daemon.error] transfer of 'zone/IN'
from name_server#53: failed while receiving responses: multiple RRs of singleton
type
This error means that zone on name_server contains more than one SOA record
(unlikely) or multiple CNAME records for a given name (likely). Either situation
is in volation of DNS RFC's.
BIND 9.x servers cannot be forced to transfer a zone with these errors. BIND 8.x
offers a multiple-cnames directive that allows multiple CNAME records for a
given name.
To fix the problem, first confirm that there is not more than one SOA record for
the zone:
dig @name_server zone axfr | grep SOA
If only one SOA record is returned, the problem is likely multiple CNAME records
for a given name.
Generate a list of multiple CNAMEs:
for i in `dig @name_server zone axfr | grep CNAME | awk '{print $1}' | sort |
uniq -d`
do
dig @name_server zone axfr | grep "^$i"
done
An easy way to identify multiple CNAMES is with the h2n utility:
h2n -V zone 2>&1 | grep "already exists as a CNAME"
Example:
mail.host.com. 14400 IN CNAME host1.host.com.
mail.host.com. 14400 IN CNAME host2.host.com.
These multiple CNAME records can be rewritten as multiple A records (using IP
addresses instead of hostnames) to achieve "load-balancing" and RFC compliance:
mail.host.com. 14400 IN A IP_address_of_host1.host.com.
mail.host.com. 14400 IN A IP_address_of_host2.host.com.
The records have to be modified on name_server's zone file in order to fix the
"multiple RRs of singleton type" errors.
Last modified: 04/02/2003
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