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description: IP Classes and Ranges
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# IP Classes and Ranges

IP Classes and Ranges

IP addresses are assigned to differentiate organization and blocks.

These blocks are divided into 5 classes but we will learn only about 3.

Class - A First Octet Address - 1-126 Default Subnet Mask - 255.0.0.0

Class - B First Octet Address - 128-191 Default Subnet Mask - 255.255.0.0

Class - C First Octet Address - 192-223 Default Subnet Mask - 255.255.255.0

127 is reserved for loopback testing.

Class A supports 16 million hosts on a 126 networks.

This class (A) is mainly given to large organizations because of the tremendous amount of ip address it can give out.

Class B supports 65 thousand host on 16 thousand networks.

This class (B) is given to medium size organization.

Class C supports 254 hosts on two million networks.

This class ( C ) given to small organizational.

Public ip addresses are publicly registered on the internet which basically means that if you have a public ip address, you have access to the internet.

Private IP -

Not publicly registered.

Cannot directly access the internet with a private ip.

The RFC-1918 standard created private ip addressing to prevent the shortage of public ip address available to ISPs and subscribers (10 Computer - 10 Private ip and 1 public ip)

Private ip addresses are typically used on local networks such as home, schools and businesses.

Private IP Ranges -

Class - A IP Range - 10.0.0.0-10.255.255.255 Subnet Mask - 255.0.0.0

Class - B IP Range - 172.16.0.0- 172.31.255.255 Subnet Mask - 255.255.0.0

Class - C IP Range - 192.168.0.0 - 192.168.255.255 Subnet Mask - 255.255.255.0
