PHP & Lynx can't resolve any domains created with WHM

[promixe]

Hi,
I was trying to access a file (located on my local server, different domain name) from a PHP script through HTTP and the script was returning a 404 error. I looked the file up in the browser on my client machine and of course it was there.
Then I launched Lynx in the terminal and typed in my main shared-IP domain name and it said "cPanel - There is no website configured for this address". I typed in the IP address of that site and it popped up right away. Then http://xxx.xxx.xxx.xxx/~username/resource.file worked perfectly while http://username.com/resource.file was returning 404 both in Lynx & PHP and was working fine from any remote machine.
The only name that resolves properly on the serverside is my main dedicated-IP domain.

I'm a newbie so I'm a little puzzled about steps to take to repair that problem. Any help would be greatly appreciated!
Thanks!

 

[promixe]

A little follow up:
I manually typed xxx.xxx.xxx.xxx needed_sharedIP_domain.com in /etc/hosts and it works now. But what I'm wondering about is do I have to enter this for all 40 of my domains? Isn't CPanel somehow supposed to do this automatically? Or am I doing something wrong by manually modifying /etc/hosts to fix this specific problem?
Thanks.