Hello,

I'm hoping someone can point me in the right direction here. I am new to managing DHCP & DNS and we have DHCP & DNS setup on the domain controller. I have read through many of the technet articles on best practices ect. but have not come across something that addresses my questions.

My current setup is as follows. 

server 2008 R2

On my scopes I have DNS set to enable dynamic updates checked and always dynamically update DNS A and PTR records along with discard A and PTR records when lease is deleted. I do not have name protection setup. I do have credentials setup under the advance tab and I do have the server inside the group DnsUpdateProxy within AD. I also have scavenging turned on the server set to 7 days and I have it setup on  the forward lookup zone to 7 days and reverse lookup zones.  I have a test zone I am working with and it's reverse lookup is set to 1 hour for scavenging. 

Q1. When I log in and grab an IP from my test scope in the RLZ the time stamp is 30 minutes behind when I actually log in why? My actual lease time within DHCP is correct as it matches my server's time.

I am trying to get the following behavior to occur and maybe it's not possible. User comes into location A gets an IP, that workstation gets an A record and PTR record. The user leaves location A and goes to location B before there lease has expired. When they get to location B and get a new IP I want the A record and PTR record to be purged from location A and now be updated with the new info from location B. It's obviously going to be the same host name as these are laptops I'm talking about but with a new IP. The reason for this is I have an application that relies on the A and PTR record and if there's multiple PTR records they won't get into the application.

If I cannot get the above to work as stated, I would like to set my lease time really low and have it purge the records once the lease is up. 

when my lease expires in this setup my PTR record does not get purged automatically, it's not until I tell the server to scavenge stale resource records that it disappears. What's really interesting about this is when I VPN in and get an IP from this same server and my VPN scope is setup exactly like my test scope and it's the same for the reverse lookup zone. When I disconnect my session from VPN my records in DHCP , FLZ and RLZ get purged immediately. I have called Cisco and they confirmed it's not my VPN client or the Firewall making this happen.

I have tested also by properly shutting down my laptop and doing an IPCONFIG /release and both of those things don't force the records to get purged automatically like they do when I leave my VPN session.  

Any help would be appreciated! 

Hi MCU,

By default, the client registers its DNS A record, and the DHCP server registers the DNS PTR record of the client. We could choose Dynamically update DNS A and PTR records only if requested by the DHCP clients. And if it helps.

According to your description, I suppose you are using two different DHCP servers at two sites. Am I right? By default, when client reconnects network, it would request for the same IP address if the lease hasn't expired. You have configured different IP ranges on them?

It would help to analyze the problem if you could provide some information about your network topology.

Best Regards,

Leo