How to find your DHCP Server Address under Mac OS X

From “Automatica Blog—Specialist Apple Mac support for creative professionals, Melbourne Australia”, edited slightly for clarity and grammar:

Use this command to determine the IP address of the DHCP server your Mac is currently using:

ipconfig getoption en0 server_identifier

You can also do more with ipconfig, such as determine the router address for an interface:

ipconfig getoption en0 router