If you made changes to the configuration of your DHCP (dhcpd) server, you will have to stop and restart the server manually. On OpenBSD and Unix like operating system, you kill the dhcpd server and restart manually. Another option is to send HUP (SIGHUP) to dhcpd server.
Method#1: Find dhcpd PID and kill it
Type the following ps command to find dhcpd PID as root user:
# ps ax | grep dhcpd
USER PID %CPU %MEM VSZ RSS TT STAT STARTED TIME COMMAND _dhcp 13420 0.0 0.1 588 568 ?? Ss 10:27PM 0:00.04 dhcpd re0
You need to kill that process with kill command.
# kill -9 13420
To start dhcpd, type the following commands:
# touch /var/db/dhcpd.leases
# dhcpd -q re0
Method #2: Say hello to /etc/rc.d/dhcpd script
You can skip all of the above commands. Use rc script as follows to start, stop, restart, and check dhcpd server on OpenBSD: