Caching and upper case issue with BIND 9.9.7-P3

cypher Nix ciphernix at
Wed Sep 23 17:44:11 UTC 2015

On Wednesday, September 23, 2015 at 12:18:37 PM UTC-4, Evan Hunt wrote:
> ... that's odd, the new case compression behavior was introduced a fair
> bit earlier than that; are you sure you weren't upgrading a few servers
> older than 9.9.7-P2?
We've ran 9.9.4, 9.9.6, 9.9.7, and 9.9.7-P2. We never had an issue until upgrading to 9.9.7-p3. Only one of the dozen severs we updated to experience this case issue. The issue cleared up once BIND was stopped and then restarted. 

> Those applications should be changed to use strcasecmp() not strcmp().
Application owners have been asked to update their code. However, restarting BIND seem to have corrected the issue we were seeing.

> However, if that's not practical, you can configure named to work the way
> it used to for selected clients, or for all clients.
> The case of the question is preserved in responses, but the case of the
> answer can change. BIND (and most other DNS implementations) used to
> compress names in responses in a way that forced the the answer to
> conform to the case of the question.  But the specification actually
> says to preserve the original owner's case whenever possible, so we
> changed it.
Thanks for clarifying. It seems like our server in question was actually changing the case to upper case for just one domain. This behavior stopped once we bounced the server. However, I feel that the application should account for different case in DNS names.

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