use server name instead of ip address

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http://unix.stackexchange.com – installed apache 2 in my ubuntu server and I use many web application like osc , glpi. to brows these applications I have to write @ip/glpi in browser. my purpose is to use servername instead of ip address. what is the way to do this action thank, system info: Ubuntu 11.10 PHP 5.3.6 Apache 2.2.20 MySQL 5.1.67 (HowTos)