DHCP server issues lease with wrong subnet mask

[Richard Falt]

We are using the DHCP Server on HP-UX 11.11. Sometimes when Win9x clients renew their leases they get a Class A subnet mask instead of a Class C. A simple release/renew takes careof the problem but what might be causing this, any ideas?

dhcptab:
dhcp_pool_group: pool-name=MYPOOL: addr-pool-start-address=10.27.64.1: addr-pool-last-address=10.27.64.254: reserved-for-other=10.27.64.150 10.27.64.254: lease-time=604800: lease-policy=accept-new-clients: allow-bootp-clients=FALSE: hn: subnet-mask=255.255.255.0: gw=10.27.64.228: ns=10.27.64.229 10.27.64.230: ds=10.27.64.231: lg=10.27.64.232: dn=mydomain.com: na=10.27.64.228 10.27.64.229 10.27.64.230

Sincerely,

Richard Falt

[Steven Gillard_2]

Your configuration certainly looks ok - is that the only pool group in dhcptab? A few things to check:

* Make sure you're not running another DHCP server on the network that might be responding first in some cases.

* Are you relaying the requests through a gateway or router? If so you might want to double check the configuration there, and check with the vendor for any firmware updates that might fix DHCP related problems.

* It could also be a client problem, so check the MS site for patches.

* If all else fails try to get a trace of the problem using dhcptools -t (see the dhcptools man page) or a packet sniffer like tcpdump. That might be tricky but is usually the only way to track down these types of problems.

Regards,
Steve