Mac OS X 10.6: Editing DNS and search domain settings
You can 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 applications.
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 Finder’s Connect To Server dialog to connect to server1.campus.university.edu.
To enter a DNS server address and search domains:
Choose Apple menu > System Preferences, and then click Network.
Select the network connection service you want to use (such as AirPort or Ethernet, unless you named it something else) from the list, and then click Advanced.
Click DNS, and 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 and enter the search domain, apple.com for example.
When you’re finished, click OK.
Domains are searched in the order you list them, and 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, university.edu.