Wednesday, June 3, 2009

Zombie DNS PTR Records

Zombie DNS PTR Records: Or, The PTR Records That Will Not Die
Do you ever have this problem in your reverse, AD-integrated DNS zones?
  • You discover an old manual PTR record that conflicts with a new dynamic registration and you delete it
  • It comes back

Sure, you can also have that problem even if it doesn't conflict with a new dynamic registration--it's just that you don't normally find this issue until you're looking to see why you're having issues in the first place. And I won't go into all the problems you may have from duplicate PTR registrations.

Anyway...what do you do?

Everytime you delete it, the stupid PTR just comes back.

Here's the trick I use. Let's say the problem record is PTR 10.20.30.40;
i.e. 40.30.20.10.in-addr.arpa.

  • Go into the DNS MMC and drill down to the PTR record.
  • Select the offending record, 40.30.20.10.in-addr.arpa and right-click, delete it
  • Select the parent zone, in this case 30; as in 30.20.10.in-addr.arpa
  • Right click on the parent zone and select to create a New Domain... from the pop-up menu
  • The name of the new domain is the name of the offending record, i.e. 40
  • Let this change replicate
  • Delete the zone, i.e. right-click on 40 and delete it

That will permanently delete the offending PTR record and keep it from appearing again.

Hope this helps someone!

Amy

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