Classless zones - & Dynamic Updates

Kevin Darcy kcd at
Thu Mar 30 02:45:49 UTC 2000

Barry Margolin wrote:

> In article <F2413A849CC9D211AC3500805FFE3E97099352 at swan.bcsc.GOV.BC.CA>,
> Evans, Lorne R ISTA:EX <Lorne.Evans at> wrote:
> >       I took a quick peek at both the archives and  RFC 2317 - but came up
> >empty.  Are there any restrictions on Dynamic Updates of Classless
> > zones?  The W2K MSFT Server Resource Kit doc states:
> >
> >               "NOTE Dynamic update does not work with classless
> > zones.  If you need to dynamically update PTR resource records,
> >do not use classless zones".
> >
> >               I am curious as to whether this is a generic DNS Server
> >restriction - BIND and W2K DNS Server - or - just a  W2K DNS client / DHCP
> >Server  restriction.  As well - could somebody possilby provide insight as
> >to why this might be a restriction?
> The general problem is that the client doesn't know the name of the reverse
> domain to update.  Classless reverse domains are essentially a trick that
> someone discovered.  With normal reverse DNS, if you have the address
> w.x.y.z, you can assume that you need to update an entry in the
> zone, but with classless the reverse zone
> can be just about anything.

A sensible DynUpdate client should be able to *figure* *out* what zone to update,
of course, by simply looking at the Authority section of a query response. But
then this is Microsoft we're talking about here...

- Kevin

More information about the bind-users mailing list