[dns-operations] TC=1 with RA=0 from a recursive resolver

Florian Weimer fweimer at redhat.com
Fri Mar 18 19:20:04 UTC 2016

We have received a bug report that our stub resolver does not retry over
TCP when asked to do so by some Google DNS resolvers:


The reason is that we check for RA=0 first and treat the server as
unusable if the bit is cleared.  Only after that, we check the TC bit.

We could easily check the TC bit first, but not setting RA=1 on a
recursive response when you are actually willing to provide recursion
looks like a server bug.



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