Reverse lookup zones (DNS)

What would be the purpose for creating reverse lookup zones in my DNS server? Right now I'm running DNS integrated into active directory. I think it builds the forward lookup tables automatically.  What is the purpose of reverse lookup and is it difficult to implement?

Here's an error I noticed on my sniffer logs related to reverse lookup too.
any ideas?
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The purpose of reverse lookup zones is to provide a translation from numeric IP address to machine name. It is the inverse of the normal forward lookups (name->address).

Reverse lookups are used for a variety of applications.

It is not difficult to implement, the things to remember are:

- reverse DNS uses PTR records, not A records
- the address octets are listed in reverse order.
- the sub-zone must be delegated from your ISP.

- Bob (aka RLGSC)

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hi  dissolved
              Its true to reverse lookup zone translates  machine numeric addr to machine name !

      The pointers should  repersent  1.168.192 ie without subnet in reverse order to  and last degits of your ip ie 68 will be the pointing value for  fully qualified domain name i.e  server<machine name>.<domain name>

         This will directly resolve local query translating   ip address to machine name

  Keep in mind it will be a NS entry .  Do u  have  any master slave configurations ?              
dissolvedAuthor Commented:
Thanks guys. My problem is I dont know how to even begin this.

I am doing this in active directory.

-Do I need to make a new reverse lookup zone for every client PC I have?  Or just a pointer to their network (ie: 1.168.192)
-I'm setting it up now, and it is asking for network ID. I'm assuming I type the IP address of the client?
-Lastly, can someone give me an every day example of when I would use the reverse lookup zone? Thanks!
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dissolvedAuthor Commented:
ok guys, I got it working for one subnet.  I entered a zone 1.168.192-arp etc etc eetc
Now I can do nslookup 192.168.1.x  and it returns a hostname

However, I added a secondary reverse lookup zone for my network, and I cannot get it to work!
I do a nslookup 192.168.2.x from the same PC, and it doesnt find a hostname.

I have a similar situation setting up reverse dns for 5 subnets.
Could you use the following as the reverse lookup zone to cath all the subnets?

ex: 168.192-in-addr-arpa

Thanks in advance
dissolvedAuthor Commented:
Good question scobb13, I'd like to know myself. I'm assuming your using a 16 bit subnet mask?
We are not. I was just using that as an example. I have setup a test to see if that will work. I'll report to you once I have an answer.
dissolvedAuthor Commented:
thanks a lot, look forward to hearing what you find.
So far the test has shown that if you setup your reverse lookup zone like this - ex: 168.192-in-addr-arpa (Do not put any value in the 3rd octet the zone will capture all of the subnets that begin with 192.168).

The different subnets show up in this zone as folders coresponding to the different subnets.
If you have the following two subnets and then you should see a 1 and 2 folder in the zone as well as SOA and NS records.
Remember to give any changes time to replicate.
dissolvedAuthor Commented:
Awesome. Thanks for posting the results of this.  Will definitely make things a little asier.
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