Duplicate PTR records


D

Dale Nemec

Hello,
I am ending up with duplicate PTR records on my DNS
servers (AD Integrated).

I have Dynamic DNS set with the DHCP server to create the
A and PTR records. I'm seeing current PTR records in the
Reverse Lookup zones, but I'm also seeing older PTR
records from previous DHCP assignments.

Is this a DHCP server issue? Is it a DNS server issue?
Is there a registry key to set somewhere so that only one
PTR record can exist at a time?

Thanks in advance!
Dale
 
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K

Kevin D. Goodknecht Sr. [MVP]

Dale said:
Hello,
I am ending up with duplicate PTR records on my DNS
servers (AD Integrated).

I have Dynamic DNS set with the DHCP server to create the
A and PTR records. I'm seeing current PTR records in the
Reverse Lookup zones, but I'm also seeing older PTR
records from previous DHCP assignments.

Is this a DHCP server issue? Is it a DNS server issue?
Is there a registry key to set somewhere so that only one
PTR record can exist at a time?

Thanks in advance!
Dale

It is likely the issue is cause from laptop users and users who just power
off their computer without going through shutdown. There isn't much you can
do for this except reduce the lease time.
DHCP should remove the records it registers when the lease expires. Default
is 8 days on a lease.
 
G

Guest

-----Original Message-----


It is likely the issue is cause from laptop users and users who just power
off their computer without going through shutdown. There isn't much you can
do for this except reduce the lease time.
DHCP should remove the records it registers when the lease expires. Default
is 8 days on a lease.


--
Best regards,
Kevin D4 Dad Goodknecht Sr. [MVP]
Hope This Helps
===================================

Thanks for the quick reply, Kevin.

I forgot to mention in my earlier post that the DHCP
Lease time is currently set to 1 hour, so they are
already as reduced as I want to go.

Is there nothing else to do then?

Dale
 
D

Deji Akomolafe

This is the expected behavior if you don't align your lease period with your
scavenging period properly. There is a documentation on scavenging on MS
site somewhere.

I have also discussed this lease period/scavenging interval collision on one
of the .dns NGs a while back. My archive doesn't go far back enough.
However, the doument I mentioned above should help you get started on
understanding the reasons for duplicates.

BTW, 1 hour is too short a lease period.

--

Sincerely,
Dèjì Akómöláfé, MCSE+M MCSA+M MCP+I
Microsoft MVP - Directory Services
www.readymaids.com - we know IT
www.akomolafe.com
Do you now realize that Today is the Tomorrow you were worried about
Yesterday? -anon
-----Original Message-----


It is likely the issue is cause from laptop users and users who just power
off their computer without going through shutdown. There isn't much you can
do for this except reduce the lease time.
DHCP should remove the records it registers when the lease expires. Default
is 8 days on a lease.


--
Best regards,
Kevin D4 Dad Goodknecht Sr. [MVP]
Hope This Helps
===================================

Thanks for the quick reply, Kevin.

I forgot to mention in my earlier post that the DHCP
Lease time is currently set to 1 hour, so they are
already as reduced as I want to go.

Is there nothing else to do then?

Dale
 
K

Kevin D. Goodknecht Sr. [MVP]

Deji said:
BTW, 1 hour is too short a lease period.

I agree, one day is as short as you want to go. Check your DHCP server to
see if it is set to remove the records when the lease expires.
 
H

Herb Martin

Kevin D. Goodknecht Sr. said:
I agree, one day is as short as you want to go. Check your DHCP server to
see if it is set to remove the records when the lease expires.


It's short but....

Some organizations have a need for such short leases (or shorter).

The class example is the University where students frequently
move their laptops from one room, floor, building.

Also examples are some highly mobile populations with
wireless networks.
 
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P

ptwilliams

We use a 12 hour lease, due to the number of users coming and going between
sites...
 
H

Herb Martin

ptwilliams said:
We use a 12 hour lease, due to the number of users coming and going between
sites...

I have seen a case made -- even if I didn't like it --
for 15 minutes.
 
H

Herb Martin

ptwilliams said:
Fifteen minutes?!?!?!

A major university Business School (really an IT Business
School) where they required EVERY graduate student to
buy a laptop with networking, and encouraged the undergrads
to do the same. (Now they all are required I think.)

People moving from area to area would take all of the leases
with them.
 
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G

Guest

I've got a similar issue with duplicate PTR records, but I have the "Remove
the records when lease expires" and several of them are kept WELL beyond the
scavenging schedule. I don't see any errors or related warnings in the
System or DNS logs. Anyone got any clue where to look for why I have some
PTR's going back over 4 months?

Thanks,
-SMFX
 
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