If you only use your Mac in one location, such as at home, then this automatic connection may be all you'll need. But if use your Mac in different locations, such as taking a MacBook to work, you must change the network connection settings each time you change locations. This tip assumes you have already been changing the network connection settings manually, and that you have the necessary network configuration information for each location.

Are you tired of changing the network settings manually each time you change locations? You can use the Mac's Network Location service to create multiple "locations." Each location has individual settings to match a specific network port's configuration. You can have one location for your home, to connect to your wired Ethernet network; one location for your office, which also uses wired Ethernet, but with different DNS (domain name server) settings; and one location for the wireless connection at your favorite coffee house.

Read more here: http://trendymediablog.com/2014/11/how-to-set-up-mac-network-locations/