OS X Yosemite: Edit DNS and search domain settings
Use Domain Name System (DNS) servers and search domains to avoid typing the complete address of Internet domains you use frequently.
DNS is the way Internet domain names are located and translated into Internet Protocol (IP) addresses.
The search domains you enter in your Network preferences are automatically appended to names you type in Internet apps.
For example, if you specify the search domain apple.com, typing “store” in your web browser takes you to store.apple.com. Or, if you use campus.university.edu as a search domain, you can type “server1” in the Connect To Server dialog in the Finder to connect to server1.campus.university.edu.
Choose Apple menu > System Preferences, then click Network.
Select the network connection service you want to use (such as Wi-Fi or Ethernet, unless you named it something else) in the list, then click Advanced.
Click DNS, then click Add at the bottom of the DNS Servers list. Enter the IPv4 or IPv6 address for the DNS server.
Click Add at the bottom of the Search Domain list, then enter the search domain, for example, apple.com.
When you’re finished, click OK.
Domains are searched in the order you list them; the search stops when a valid name is found.
To search a name hierarchy, use search domains of varying scope. For example: building.campus.university.edu, campus.university.edu, and university.edu.