Hi,
As SeLLeRoNe said you need to get a addon IP address from your hosting provider, most dedicated servers come with at least one extra IP address, so it's possible you already have one (just check with them).
After you have it, you can follow these instructions to set that IP address as a dedicated IP for a specific domain.
1) Login to directadmin from your MAIN IP address
2) Go to IP Management
3) Enter the (new) IP and appropriate netmask (check with your host, or if you are impatient you can try default which usually works for me).
4) Click on "Home" at top.
5) Click "Create Admin" link, make new Admin account (i.e. admin2)
6) Go back to IP management.
7) Click checkbox for the addon IP, then next to 'assign to' button, use drop down to select new admin name, click button 'assign to'.
8) Log out and go to DA panel for new IP (
http://ipaddress/2222)
9) Login to DA using the second admin account you created and the password you assigned it.
10) Follow the instructions:
While logged in as admin, do the following:
Switch to the Reseller Level panel.
Click the List Users link.
Click the Modify your own User data link.
Using the “Set IP To” dropdown list, select the IP address for the main site.
Click the Save button.
I've added dedicated IP addresses countless times using this exact method. Source for this which I bookmarked last year:
Code:
http://www.directadmin.com/forum/showthread.php?t=17739