Port

In Apache versions prior to 2.0, the Port entry points to the default port used when self-referential URLs in any of your virtual hosts attempt to connect back to the server (without explicitly appending a port number in their URLs). We'll discuss self-referential URLs in more detail later in this appendix. You can specify only one port. You should use either port 80 (the default) or port 443. Use port 443 if you want the default value for self-referential URLs to point to the secured content; otherwise, use port 80.