Today we have released the PowerDNS Recursor 4.1.7. It is an update to relax EDNS compliance requirements from upstream authoritative servers.
Recursor version 4.1.5 (and, by extension, 4.1.6), contains a fix for Security Advisory 2018-07. One part of that fix is a stricter fallback to non-EDNS queries when EDNS queries fail. It turns out that there are several authoritative servers on the Internet that have such bad EDNS handling, that the domains hosted on them stop resolving with 4.1.5. The 4.1.7 release has relaxed the EDNS compliance requirement and includes an alternative fix for 2018-07.
Since reports of this started coming in yesterday, some domains have been fixed by their owners, but a long tail of broken zones remains for now.
We have decided to release this increase in strictness in the PowerDNS Recursor 4.2.0, so that domain owners can work on their server’s compliance. We urge operators of authoritative servers to check their domains and servers with the EDNS compliance tool and act upon its results. Increased EDNS compliance strictness will be added to many DNS resolvers coming next February.
The changelog is as follows:
- #7172: Revert ‘Keep the EDNS status of a server on FormErr with EDNS’
- #7174: Refuse queries for all meta-types