How do you have dhcpd reload its configuration file?

At this time, the dhcpd server doesn't have any reload mechanism. It doesn't handle HUP signal nor have a 'soft' reconfiguration method. The server has to be stopped and restarted, for example:

kill `cat /var/run/dhcpd.pid`

/usr/local/sbin/dhcpd

If you have a startup script for dhcpd, you may be able to reload the configuration (by restarting) such as:

/etc/init.d/dhcpd restart

Depending on the use, this is usually not a problem in terms of service outages because clients retransmit and it is hard for anyone to notice a problem in the time it takes the server to start back up again.