BIND started replying to queries for .com with .COM

[Phil Mayers]

On 30/03/2016 13:15, Tony Finch wrote:
> Phil Mayers <p.mayers at imperial.ac.uk> wrote:
>> On 30/03/16 10:50, Tony Finch wrote:
>>>
>>> Yes, we encountered that problem recently :-) You can revert to the old
>>> behaviour using
>>>
>>> 	no-case-compress { any; };
>>
>> +1 super confusing when we first ran into it (Exim dnslookup.c, by any chance? ;o)
>
> Actually Nagios, and it sounds like Mike Bernhardt encountered it there as
> well. I'm now wondering why we haven't noticed a problem with Exim...

You'll only see it if the resolver your Exim process is using has an 
"unexpected" case version of a label cached (unlikely in normal 
operation) and you look for it in your logs.

We were seeing things like "=> blah at google.COM" one one Exim node, and 
the lower-case on another, and the difference was in the resolver cache, 
not what the client sent.