Which port is used for Software Updates on the Apple Server?

Hi All: My company recently bought an Apple Server to use for our websites and e-mail. I have used Apple computers for years, but have no experience on the server. I tried to set the Server Admin panel to update the software using port 80, but the Software Update Service turns off when I try to save the settings using port 80. I can save the settings using a random port number such as port 90, but I want to be sure I am using the correct port number. Does any person know which port to use, to help this newbie? Thank you very much for your time, Jackie EC Corp. USA