6.2.1 IP Addresses Explained
IP (Internet Protocol) addresses are expressed as 4 decimal numbers separated by periods, for example:
216.103.126.155
10.1.1.6
Each decimal number must be between 0 and 255. The total IP address is a
cent IP addresses. There are always 2N IP addresses in a local network. The netmask (also called subnet mask) determines how many IP addresses belong to the local network. The netmask is also a
255.255.255.0
This netmask has 8 zero bits in the least significant portion, and this means that 28 addresses are a part of the local network. Applied to the IP address above (216.103.126.155), this netmask would indicate that the following IP addresses belong to the local network:
216.103.126.0
216.103.126.1
216.103.126.2
etc.
216.103.126.254
216.103.126.255
The lowest and highest address are reserved for special purposes. The lowest address (216.102.126.0) is used to identify the local network. The highest address (216.102.126.255) is used as a broadcast address. Usually one other address is used for the address of the gateway out of the network. This leaves 256 - 3 = 253 available IP addresses for the example given.
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