Ask Dr. Intranet

BOSTON (06/12/2000) - We're using the dynamic host configuration protocol server available from wwwnet. ware/dhcpd/ on a Sun Microsystems Inc. Solaris machine to provide dynamic IP addresses for our intranet workstations running Windows. dhcpd software compiled, and it seems to run now that we've created the files/etc/bootptab and /etc/ dhcpd.conf using the "gen-config" tool that comes with the package. Our Windows workstations get IP addresses from the server, but the subnet mask gets set to rather than The worst part is the workstation can't release the IP address because it can't talk to the network with the bad subnet mask. The bootptab file is a list of entries that look like "dynamic198-150-65-5:ip=". What do we have to add or change to fix the subnet mask setting problem we're having?

Add the subnet mask value to your bootptab entries through the "tc=default" field you have in your bootptab records. Add ":sm=" to the end of the line labeled "default:" in your bootptab file and restart dhcpd. If you don't have a "default" entry yet, add the line "default:sm=" to the top of the bootptab file and restart dhcpd. In addition to the CMU-3.3.7+PU-8 dhcpd you're using, there's a downloadable dhcpd implementation available from the Internet Software Consortium ( that's under development.

Blass is a network architect at Sprint Paranet in Houston. He can be contacted at

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