Without IPv6 half of the queries yield SERVFAIL

[sthaug at nethelp.no]

> ! I tried to use this recommendation, https://kb.isc.org/docs/aa-00206,
> ! marking all IPv6 addrs as bogus, but it does not make a difference in
> ! behaviour.
> 
> Update: Actually there is a difference if this recommended
> configuration is present or not - only the NXDOMAIN outcome is the
> same in both cases.

Have you tried:

listen-on-v6    { none; };

Steinar Haug, Nethelp consulting, sthaug at nethelp.no