IP Addresses

IP addresses consist of a 32 bit number and is represented by the dot-decimal format.
for example: 142.110.237.1 is an IP address.
There are 4 decimal digits separated by three dots. Each digit is allowed the range of 0 to 255 which corresponds to 8 bits (one byte) of information.
A portion of an IP address represents the network address and the remaining portion the host address.
For example: 142.110.237.
1 is the IP address of a firewall.
The network that the firewall resided on is 142.110.237.0 (Note: IP addresses that end in a 0 represent network addresses).
The host address of the firewall is 0.0.0.1 (Note: the network portion of the IP address is represented by 0s). Each host on the network and Internet must have a unique IP address. There are ways around having each host a unique IP address and they are discussed under firewalls. The Network Information Center (NIC) assigns network addresses to the Internet.
You must apply to receive a IP network address. Depending on the class (more on this later) of the IP address, you can then assign as many host IP addresses as allowed.
An alternative is to "rent" IP addresses from your local Internet Service Provider (ISP).
They usually own the rights to a block of IP addresses and will rent them out for a fee.


Class A addresses

IP address range 1.0.0.0 to 127.0.0.0
Number of networks available: 125 (see special addresses below)
Number of hosts per network: 16,777,214
Net Mask: 255.0.0.0 (first 8 bits are ones)
Special Addresses: 10.0.0.0 is used for networks not connected to the Internet

Class B addresses
IP address range 128.0.0.0 to 191.0.0.0
Number of networks available: 16,382 (see special addresses below)
Number of hosts per network: 65,534
Net Mask: 255.255.0.0 (first 16 bits are ones)
Special Addresses: 172.16.0.0 to 172.31.0.0 are used for networks no connected to the Internet

Class C addresses
IP address range 192.0.0.0 to 223.0.0.0
Number of networks available: 2,097,150 (see special addresses below)
Number of hosts per network: 254
Net Mask: 255.255.255.0 (first 24 bits are ones)
Special Addresses: 192.168.1.0 to 192.168.255.0 are used for networks not connected to the Internet

Class D Addresses
IP address range 224.0.0.0 to 239.0.0.0
Use: Multicasting addresses

Class E Addresses
IP address range 240.0.0.0 to 255.0.0.0
Use: Reserved by the Internet for its own use.

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