Question : 2003 DNS conf : ClassLess reverse zone

I'm wondering what is the best practice when you are configuring a DNS reverse zone in a classless environment.
I had a look to Microsoft kb174419 and I understand quite well the concept when using class C address and subnetting.

My question is concerning a class B address and subnetting :
exemple : 172.16.8.0/21 and 172.16.16.0/21
in such case :
Are we supposed to create a reverse zone 172.16.in-addr.arpa with two new domain 8/21 and 16/21, or 2 reverse zone named 172.16.8.in-addr.arpa and 172.16.16.in-addr.arpa ?

In the first case, I'm not abble to create  a domain 8/21. Only a new domain named 8. which is problematic because when I try to add a host with an IP 172.16.9.10 who belong to the subnet 172.16.8.0/21, the DNS automatically create a new domain named "9".
(Note that if you are using a subnet /24 instead of /21 it works correctly. or it seems)

So my question is :
What is the best practice to configure DNS reverse zone in a classless environment, with a class B based address, on a 2k3 server.

Note: No delegation involved.

Answer : 2003 DNS conf : ClassLess reverse zone

Classless zones are only applicable when resolving public names because you have no way to address a classless zone except via delegation and aliasing.

You might just be best served by creating 172.16.in-addr.arpa, it's far too large, but the alternative is to create "Class C" zones for each /24 bit subnet within the /21.

Chris