post up your pcap of the dhcp conversation, discover, offer, request and ack.
If your saying the dhcpd is sending out the correct mask, and others are using it correctly - then you got something wacked on those clients!
Options shows that there was an option 1 of type Text with a blank value. Option 1 is - tada - subnet mask.
So yeah that would F it up big time!! But you would of seen that in the offer, or lack of the offer containing mask.
