Reverse DNS Zone

jlhct

Hey Everybody,

Is there some kind of way the Reverse DNS zone will automatically get rid of old records. In a couple of cases it seems there are about 3 or 4 Reverse records for an IP address associated with computer names that no longer exist on the network. When we try to do a Ping -a for an IP address we get one of these bogus names so we can't tell which PC really has this address.

Any Ideas? Thanks a lot!

royal

Clients can't automatically register their own PTR records in DNS. What you would need, is to use DHCP. DHCP has the ability to use DDNS and create PTR records for clients that are leasing an ip address. You would also need to configure your DNS server to allow for DDNS. When a client renews a lease, dhcp will keep the dns record up to date. If a client gets a new ip address from dhcp, dhcp will update accordingly. Also, you can turn on scavenging (both at reverse lookup zone level as well as server level) hich will ensure stale records will not become old residue in your dns database. Manual dns entries don't have a timestamp so scavenging wont remove manual entries.

JLL

Take a look at the DNS tab of the DHCP Server properties. Should be an option for discarding old records (or something to that effect).

Let me know how it goes!

JLuna

Slowhand

icroyal wrote:

Clients can't automatically register their own PTR records in DNS. What you would need, is to use DHCP. DHCP has the ability to use DDNS and create PTR records for clients that are leasing an ip address. You would also need to configure your DNS server to allow for DDNS. When a client renews a lease, dhcp will keep the dns record up to date. If a client gets a new ip address from dhcp, dhcp will update accordingly. Also, you can turn on scavenging (both at reverse lookup zone level as well as server level) hich will ensure stale records will not become old residue in your dns database. Manual dns entries don't have a timestamp so scavenging wont remove manual entries.

It depends on if it's a Windows network, or not. On a Windows network, Windows 2000 and XP clients can register their own DNS records. (Server 2000/2003 using DHCP is not recommended). With NT4, Win9x, or *NIX clients, the DHCP server has to register the DNS records for them. (One thing to note, though, is that there is a special security group, the name of which escapes me at the moment, that the DHCP servers should be a part of if they are going to register DNS records. If they're not part of this group, they'll own the DNS records they register, and if the older clients upgrade to 2000 or XP, those clients won't be able to register their own anymore.) On a network running BIND, for example, all bets are off.

jlhct

Everytime I post here I ALWAYS get VERY informative responses and I really APPRECIATE it!

The Scavenging function wasn't enabled, so I enabled that. I also looked in the DHCP service and chose Automatically update DNS, Discard records when lease is deleted & dynamically update for clients that do not request updates. This is a Win2003 network BTW.

I was able to look in DHCP and see the leases for the IP addresses we needed to lookup. They all matched the PC's that are still in the network. So now it's just a matter of DNS giving back the correct info.

royal

Slowhand wrote:

It depends on if it's a Windows network, or not. On a Windows network, Windows 2000 and XP clients can register their own DNS records.

I remember reading in MSPRESS that 2k/xp clients can register their own A records but cannot register their own PTR records. That is why I stated he still needs DHCP to do the DDNS PTR registration. I'm trying to find a document on technet to verify this.

Edit: I'll try to find documentation later on. I'm trying to fix a DC here at work right now.

Also, that group that you were talking about is called dnsupdateproxy.

RTmarc

Group Policy will allow client machines to register their PTR records:

Computer Config > Admin Templates > Network > DNS Client > Register PTR Records

Only XP and Server 2003 are capable of doing this though.

jescab

did you try
start > run >cmd
then type ipconfig /flushdns

jlhct

RTmarc wrote:

Group Policy will allow client machines to register their PTR records:

Computer Config > Admin Templates > Network > DNS Client > Register PTR Records

Only XP and Server 2003 are capable of doing this though.

Wow, I didn't realize this...that would be worth a try!

jlhct

jescab wrote:

did you try
start > run >cmd
then type ipconfig /flushdns

No I didn't try this, at first I didn't know which PC's were giving the wrong info

jlhct

RTmarc wrote:

Group Policy will allow client machines to register their PTR records:

Computer Config > Admin Templates > Network > DNS Client > Register PTR Records

Only XP and Server 2003 are capable of doing this though.

I checked this morning, the purging of records seemed to do the trick...all of the DNS entries seem to be up to date, thanks!