Subject: Re: NetBSD Security Advisory 2003-018: DNS negative cache poisoning
To: Andreas Gustafsson <>
From: David Maxwell <>
List: current-users
Date: 12/18/2003 13:39:41
On Thu, Dec 18, 2003 at 10:33:04AM -0800, Andreas Gustafsson wrote:
> David Maxwell <> said:
> > Bind 9 has limitations for IPv6 users, that makes it a poor candidate
> > for inclusion in the base OS until they are resolved.
> > 
> > For individuals with no IPv6 requirements, it is certainly an
> > appropriate way to go.
> I think you have misunderstood the note in src/doc/3RDPARTY saying
> "9.2.x has some issues (A6 queries for glue, for instance)".
> I believe the note is referring to the fact that when a 9.2 server is
> looking up missing name server addresses, it sends queries of type A,
> AAAA, *and* A6.  Since the use of A6 has been effectively deprecated
> and almost no one actually publishes A6 records, sending these A6
> queries will in practice amount to a waste of some small amount of CPU
> and bandwidth.  It's an issue, but IMO a minor one.
> Saying that this is a "limitation for IPv6 users" is misleading - if
> these A6 glue lookups are indeed an issue, they are just as much an
> issue for IPv4 users as they are for IPv6 users, since they happen
> regardless of the query type and transport.
> As far as I know, there are no actual "limitations for IPv6 users" in
> BIND 9.2.  Lookups of IPv6 addresses, reverse lookups of IPv6
> addresses, and lookups over IPv6 transport all work just fine.

Thanks for the explanation. That's much clearer. It doesn't sound like
it should be an issue against switching to bind9 at all then.

David Maxwell,| --> Although some of you out
there might find a microwave oven controlled by a Unix system an attractive
idea, controlling a microwave oven is easily accomplished with the smallest
of microcontrollers. - Russ Hersch - (Microcontroller primer and FAQ)