ＩＰ地址的一些問題

(1a)
To find out the IP address of your own PC, type the command
ipconfig
in DOS prompt

In Unix, the command is ifconfig

(1b)
If your know the hostname of the another computer,
ping hostname
can display the IP address.
But, nowaday some computers has blocked the ping protocol.

(2)
Knowing the IP address can do many things.

When your computer join a network (e.g. a LAN or the internet ocean), you must identify your computer.

IP address is that identifier.
Nowaday, we are using IPv4. The IP address is a 32-bit number displayed as AAA.BBB.CCC.DDD (each part ranges from 0 to 255).

In theory, this 32-bit number can represent many computers.
But, there is some standard that you cannot use up all the 256 numbers from 0 to 255.

Anyway, that number is the identifier of your number, just similar to the case that your HKID number (or your student number) is the identifier of you.

After knowing the IP, the whole world could reach your computer using many different protocols.

For example, in unix, you can telnet the-ip-address to tenet to that computer
Or, you can ftp the-ip-address to use FTP to upload/download files.
If that computer is a web browser, you can http://the-ip-address to get the default web page of that web server.

(3).
Server IP and client IP have no difference. Both are 32-bit numeric number.
The only difference of 2 numeric numbers is the numeric value.
However, in the internet world, some computers start to use IPv6. IPv6 use a 128-bit (?) IP address. Most others are still using IPv4 (32-bit IP address)