Sharepoint 2010 not able to access with server name in URL from out side the server

Hi,

I am not able to access the Sharepoint 2010 site out side the server which has alternate access mapping and FBA Configured site.

I can access the site with IP Adress in URL from outside the server which has vpn connection.But not able to access same site with server name in URL.

example : able to access site like : http://1.2.3.4:4444

Not able to access site like : http://abcd:4444

i have given host entry in my local machine aswell.

anyone suggest me how to configure the sharepoint 2010 site access out side the server with servername also instead of ipaddress.

Thanks in Advance

Regards

Umamaheswar