The current config syntax allows a single kind of listening address, `listen-address`. This sets the `local-address` option in `/etc/powerdns/recursor.conf`. Unfortunately, `local-address` is only for IPv4 addresses; a separate `local-ipv6` setting in recursor.conf is required for IPv6 addresses. As a result, this configuration:
# show service dns
creates this setting in `recursor.conf`:
The server does not, in fact, listen on any of the IPv6 addresses, although it does listen on the IPv4 addresses without complaint.
There should probably be a separate `listen-address-v6` config option, or something similar.