How urgent is this? At this time, I see only an optimization to
avoid sending a query about an IPv4 client address to a DNSXL service
that provides reputation only about IPv6 addresses (and vice versa).
With postscreen parallel DNSXL lookups that is not a disaster.
I am concerned about the potential explosion of complexity with:
(query with A or AAAA)
* (service provides reputation for IPv4 or IPv6 clients).
I think that we can do better than maintaining multiple parallel
lists. For example, use one list and indicate per DNSXL that they
can be only used for one kind of client IP address. The default
should remain both as it is now.
Wietse
