Hello,
I am trying to figure out why some domain names are not resolving on my instance of Knot resolver over DoH with some clients. I was able to reproduce this issue with [doh](
https://github.com/curl/doh) client built on libcurl. The problem never manifests with kdig (neither with DoH, nor DoT nor Do53).
During this, I noticed something strange. For domain name
github.com (which sometimes returns no A record), I always receive an answer with TTL set to 60. It seems like this name does not get cached at all. See the test output below.
Interestingly, if I delete cache files and restart the resolver, the TTL starts decreasing as expected. Is this a sign that something was wrong with the cache before? Or is this some sort of cache optimization for low TTL records?
Here is the test output:
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Best regards,
Ondřej Caletka