Stale cache feature problems
borjam at sarenet.es
Thu Nov 11 09:27:08 UTC 2021
I’ve been trying the stale answers feature out of curiosity (seems to be a useful idea) but I have ran into problems.
I tried at home, so nobody was actually hurt!
I am running BIND 9.16.22 built from ports on FreeBSD 13-STABLE and I didn’t attempt any tuning, I just enabled
First problem: I experienced random SERVFAILS with no apparent reason while i had the feature turned on. I think it
especially affected CDNs with multiple chained CNAMES and complex DNS server infrastructures.
As far as I know I have good connectivity, both IPv4 and IPv6.
The queries that failed a lot were:
doh.xfinity.com A and AAAA
ping.ui.com A and AAAA
gs.loc.apple.com A and AAAA
nv2-namain-deco.netatmo.net A and AAAA
The errors started when I enabled the feature, and they completely went away when I disabled it days later (I feed the
querylog and errors into Graylog)
Second problem: There is a bug. If I comment out the stale-answer-enable line on named.conf and I issue a “rndc
reconfig” the feature does not get turned off. It stays on until I restart the daemon.
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