Bind9 - multiple identical CNAME records in single resultset (cid-*.calendar.live.com)

[Mark Andrews]

Upgrade.  This is fixed in the current maintainence releases.

3452.   [bug]           Accept duplicate singleton records. [RT #32329]

Mark

In message <523175FE.1070407 at rrzn.uni-hannover.de>, Hostmaster LUH writes:
> Hello,
> 
> 
> we are facing issues using bind9 as resolving nameservers for our users.
> The problem is in resolving domains such as cid-*.calendar.live.com, e.g.
> cid-20e76408fdfb6414.calendar.live.com
> 
> Bind discards the result with the following message in syslog:
> named[1403]: error (FORMERR) resolving
> 'cid-20e76408fdfb6414.calendar.live.com/A/IN': 213.199.180.53#53
> 
> resolving the domain via dig +trace works:
> dig +trace cid-20e76408fdfb6414.calendar.live.com
> 
> ; <<>> DiG 9.8.1-P1 <<>> +trace cid-20e76408fdfb6414.calendar.live.com
> ....
> 
> cid-20e76408fdfb6414.calendar.live.com.	3600 IN	CNAME na.calendar.live.com.
> na.calendar.live.com.	3600	IN	CNAME	calendar.live.com.
> na.calendar.live.com.	3600	IN	CNAME	calendar.live.com.
> calendar.live.com.	3600	IN	A	65.54.251.146
> ;; Received 151 bytes from 65.55.226.140#53(65.55.226.140) in 119 ms
> 
> We guess the problem is in the 2 (identical) CNAME records for the same
> domain received in a single result set from ns*.msft.net, bind9 discards
> these packets as invalid/FORMERR.
> Resolving the CNAME will create a valid cache entry, resolving the A
> record afterwards will work.
> Using unbound, we are able to resolve domains properly directly.
> 
> 
> We are looking for assistance with this, something as easy as a
> configuration option to allow the (invalid?) packet to be processed
> properly as unbound does would be great.
> Of course adjusting the Microsoft nameservers to comply with the RFC
> would be better, but we already tried to contact Microsoft (domains@,
> msnhst@, opsimt@) about the issue, but so far there was no response.
> 
> 
> The cid-*.calendar.live.com domains are used to identify the calendars
> of users, the all point to the same records.
> Using bind9, this does not work, so live.com calendar is broken (for all
> of our users).
> 
> 
> 
> Sincerly,
> Torsten Glaeser
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-- 
Mark Andrews, ISC
1 Seymour St., Dundas Valley, NSW 2117, Australia
PHONE: +61 2 9871 4742                 INTERNET: marka at isc.org