You need multiple port numbers: one for the Administration Server and one for each instance of Sun Java System Web Server. The Administration Server is a special instance of the Sun Java System Web Server that you use to manage your Sun Java System Web Server.
The standard web server port number is 80 and the standard SSL-enabled web server port number is 443, but you can install Sun Java System Web Server to use any port. If you use a port other than the default port (port 80), the URL used to gain access to your home page changes. For example, if your computer is called www.siroe.com and you choose port 9753, the URL of your server will be http://www.siroe.com:9753/.
You should choose a random number for the Administration Server to make it harder for anyone to breach your server. When you configure your server, you use port number of the Administration Server. For example, for server mozilla.com, the server’s URL could be http://www.mozilla.com:2634/.
Make sure the port you choose is not already in use. On UNIX and Linux systems, you can check the file /etc/services on the server machine to make sure you do not assign a port number that is reserved for another service. If you choose a port that is currently being used by another service, the installation program prompts you for another port.
If you use UNIX or Linux, and you choose a server port number lower than 1024, you must be logged in as root to start the server. After the server binds to the port, the server changes from the root user account to the user account you specify. If you choose a port number higher than 1024, you do not have to be the root user to start the server.