May be this will help:
http://httpd.apache.org/docs/1.3/vhosts/
Lets say you have a webserver running. To access it, you use
http://hostname:port/
In case you wish the server to be accessed using 2 different hostnames.. then we need to add another DNS name for the new host name Eg:
192.168.1.34 secondhostname
With this change, you will be able to access the app running on web server using the new hostname
http://secondhostname:port/
The real problem is when you want a different app to be running when you access the webserver with different host names
http://hostname/ should display app1
http://secondhostname/ should display app2
With traditional approach, this will not work. For this most of the webservers provide options to add virtualhosts and specify what needs to be run on each virtualhost.
Hope that helps
-eNJay