2014-02-18 - News - Chris Thompson
The most recently released BIND versions (9.9.5, 9.8.7, 9.6-ESV-R11) have implemented a more pedantic interpretation of the RFCs in the area of compressing responses. It is just possible that this will cause problems for some resolving software. ISC have written a Knowledge Base article about it, which can be found at https://kb.isc.org/article/AA-01113
In particular, the name in the answer section of a response may now have a different case from that in the question section (which will always be identical to that in the original query). Previously they would (after decompression) have been identical. Resolvers are meant to use case- insensitive comparisons themselves, but this change could expose non- conformance in this area.
However, experiments we have performed so far, and information from the DNS community at large, suggests that such non-conformance is quite rare. We are therefore planning to upgrade the CUDN central nameservers (both authoritative and recursive) to BIND 9.9.5 over the next few days. Please keep an eye out for any problems that might be caused by the change, and let us (hostmaster at ucs.cam.ac.uk) know as soon as possible, while we still have the option of backing off.