response case in-sensitivity?

Mark Andrews marka at
Thu Jul 30 04:56:26 UTC 2015

In message <23DEE83F-7476-432B-92B9-F8D34D617C2F at>, Mathew Ian Eis writes:
> Howdy BIND,
> Weve been troubleshooting an issue with iOS print discovery using DNS-SD 
> for the last several weeks. We made a little bit of a breakthrough this 
> evening when we observed in a packet trace that the response case was 
> fully lowercase, regardless of the query case. It seems iOS is doing some 
> kind of case sensitive comparison between the query and the response, 
> causing DNS-SD to fail when they dont match.

Then iOS (or the application) is broken.  Domain names should always
be compared case insensitively.  Please report a bug to the app
vendor and / or Apple.

> I noticed change 3645, but my reading of the related article suggests 
> that the change was actually intended to preserve the case in a query 
> response rather than force it to lowercase.

It preserves the case of the of the owner names of the records in
the answers as received.

> My reading of that article suggests the RFC compliant behavior is to 
> preserve the case in the response, is this correct? 
> ompression-May-Cause-Problems-With-Mixed-Case-Data-and-Non-Conforming-Clie
> nts.html
> Were currently running BIND 9.9.7 (it is likely this issue was introduced 
> when we updated from 9.9.4 a while back), so Im wondering why I am 
> running into this. Is there something that I need to turn on to preserve 
> the case in the response, or, alternatively, is there something that we 
> have have inadvertently changed that would cause BIND to force the 
> response to lowercase?
> Thanks in advance,
> Mathew Eis
> Northern Arizona University
> Information Technology Services
> mathew.eis at<mailto:mathew.eis at>

Mark Andrews, ISC
1 Seymour St., Dundas Valley, NSW 2117, Australia
PHONE: +61 2 9871 4742                 INTERNET: marka at

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