invalid netmask from dhcp server

[grunky]

I've setup a dhcp server on a 1605 running c1600-y-mz.122-23.bin

The dhcp srever statement is as follows.

ip dhcp pool 8th_floor

network 192.168.20.0 255.255.255.0

dns-server 209.94.40.2 209.94.48.2

domain-name rockriver.net

default-router 192.168.20.254

option 66 ip 192.168.20.218

option 150 ip 192.168.20.218

The problem is some hosts, xp machines and Cisco 7940 phone are getting very strange broadcast addresses.

ip info on a 7940 is as follows

ip 192.168.20.137

mask 240.255.255.0 <-not a typo

gateway 192.168.20.254

I've also got xp machines w/ the same strange subnet mask.. starting w/ 240..

Anyone have ideas as why this is happening.. The hosts w/ this strange subnet mask can still connect to the outside world.. I've rebooted the router - still same strange ips.

[didyap]

You could take a capture of the dhcp process with the improper mask. Check to see if there is nothing wrong with the router. It could also have something to do with the way the dhcp client is interpreting the packet. Are the PCs getting this mask running any special software version? There are a couple of bugs documented on DHCP issues. You might want to take a look at them also.

[grunky]

The hosts that were effected were a few xp machines, a laptop running win95, and Cico 7940 phones.

I fixed the problem by removing the text and re-inserting it verbaium.

I have no idea what caused this nor why the fixed worked. Copying and comapring the running-config on the router using diff yielded nothing.