DHCP & DDNS problem

[Rainer von Bongartz]

I am configuring DHCP and dynamic DNS (DDNS) on HP-ux 11i server.

I have four different subnets and some DHCP clients (laptops) can 'travel' through this subnets.

Every time one of this clients is connected to the network an IP-Address for this client is released.
In /etc/dhcpdb this client may be found with leases for different subnets , i.E.
C 193.16.45.0: 193.16.45.192 00 1 00C017830C2C 3C5E9E18 00 Fluke-830c2c
C 193.16.46.0: 193.16.46.179 00 1 00C017830C2C 3C5E8FD0 00 Fluke-830c2c

In this case the client Fluke-830c2c had leases in 193.16.45 and 193.16.46

The problem is that the dhcp server registered the client to the DNS server in subnet 45 and now cannot assign it in subnet 46 with a new ip address as the lease is not removed from dhcpdb.

How to configure DHCP so that a lease is removed as soon as this client is conneted to a different subnet ??

[Ron Kinner]

Set your lease time very low. 120 seconds is the minimum but that's probably a bit too short. (Max is infinity) Pick a number that makes sense for you. Supposedly you can set this with SAM. Also make sure you have the DNS on the same machine and set DHCP to
dynamically update the DNS server.

"DHCP updates DNS with the host name and IP address of the client. For every client DHCP assigns a name and IP address to, it also adds an address record ("A"), a pointer record ("PTR"), and a resource record ("RR") of that client to the DNS server.
To assign a name for every IP address, there is a new tag known as "pcsn." When this boolean tag is set, the DHCP server gives priority to the name (if any) provided by the client. The name should be a fully qualified domain name (FQDN). If it is not, then the DHCP server will try appending the domain name (if set using "dn" tag) else it appends "." and updates the DDNS."

http://docs.hp.com/cgi-bin/fsearch/framedisplay?top=/hpux/onlinedocs/B2355-90741/B2355-90741_top.html&con=/hpux/onlinedocs/B2355-90741/00/00/62-con.html&toc=/hpux/onlinedocs/B2355-90741/00/00/62-toc.html&searchterms=dhcp%7clease%7ctime&queryid=20020204-130352

Ron