windows 2008 reverse dns zone for whole subnet?

Mystical_Ice
Mystical_Ice used Ask the Experts™
on
Hi,
We have a domain that used to be a flat network (172.17.2.0 /24), but was recently changed to include other subnets too, including 172.17.3.0/23 and 172.17.5.0/24.

I created a single reverse DNS zone called:
0.17.172.in-addr.arpa
But when i try to go to a forward DNS Host (A) record and update its PTR (for a host that's now on the 172.17.3.0/24 subnet), i get the error: "Warning: The associated PTR record cannot be created, probably because the referenced reverse lookup zone cannot be found".

What am I doin wrong?
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BillBondo

Commented:
Can you ping all the other subnets from each direction? By IP and name? I dont think you would need a reverse look up zone.
Principal Support Engineer
Commented:
From what I've read, you'll be better off creating separate class-C reverse lookup zones for 172.17.2.x, 172.17.3.x, and whatever other ranges are encompassed in your network than trying to create a single classless reverse lookup zone.  Dynamic updates don't work in a classless reverse zone, for example.
Mystical_Ice

Author

Commented:
This is correct - for future reference if someone is reading this question with the same problem, with reverse DNS in windows 2008 you can only specify /8, /16, or /24 subnets (or 255.0.0.0, 255.255.0.0, or 255.255.255.0 subnets respectively).

Thus even though our 172.17.2.150 /23 (255.255.254.0) contains addresses from 172.17.3.0 through 172.17.4.255, I had to create two seperate reverse lookup zones:

0.4.17.172.in-addr.arpa
and
0.3.17.172.in-addr.arpa

Did that, and right away PTR records started getting created.

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