response case in-sensitivity?

[Mathew Ian Eis]

Howdy BIND,

We’ve 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 don’t match.

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.

My reading of that article suggests the RFC compliant behavior is to preserve the case in the response, is this correct? https://deepthought.isc.org/article/AA-01113/0/Case-Insensitive-Response-Compression-May-Cause-Problems-With-Mixed-Case-Data-and-Non-Conforming-Clients.html

We’re currently running BIND 9.9.7 (it is likely this issue was introduced when we updated from 9.9.4 a while back), so I’m 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 nau.edu<mailto:mathew.eis at nau.edu>
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