How do I configure a MAC OS X computer for basic connectivity?
By default, MAC OS X is configured as a DHCP client. However, if MAC OS X has been configured with a static (manually configured) IP address, and if the computer needs to receive an IP address automatically, then MAC OS X will need to be reconfigured as a DHCP client. This document describes how to configure for DHCP setup.
Click the Apple icon on the upper-left corner and select System Preferences....
Click the Network icon in the Internet & Wireless section. The Network window appears.
On the Network window, click the Configure IPv4 drop-down menu and select Using DHCP.