We have a Windows 2003 web-server belonging to the domain ss.xx.company.com.
Is it possible to set the Domain name alias of the web-server to the value al.xx.company.com? If yes, how?
You can use DNS to do this. Obviously externally it needs to be done on your domain, and internal resolution needs to be done by your internal DNS server. You will need to make an additional A record for what name you wish to choose.
If you need any more help let me know.