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What is the valid range of a Class A network address?

  • Last Updated : 01 Oct, 2021

Let us know what an IP address is first, if you already know, skip this section. 

IP (Internet Protocol): 
It is one of the fundamental protocols inorder to have communications on the Internet. IP describes how the information is addressed, routed by networking devices. An IP address is a number identifying of a computer or another device on the Internet. A simple example could be mailing address.

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There are 2 types of IP
1. IPv4 : 32 bit long, Ex: 35.244.11.196
2. IPv6 : 128 bit long, it is so much longer than IPv4

Example for IPv4 :



1. Dotted Decimal Notation
 

IPv4: 32 bit long ( Dotted Decimal )

2. Hexadecimal Notation

IPv4: 32 bit long ( Heaxadecimal )

CLASS ADDRESSING :

  • So, In IPv4 addressing, there are 5 classes to range IP Values : Class A, B, C, D and E.
  • The order of bits in the first octet determine the classes of IP address.
  • IPv4 address is divided into two parts:
    1. Network ID 
    2. Host ID
  • The class can determine the bits used for network ID and host ID.
  • The number of total networks and hosts possible in that particular class can be calculated.
  • Only class A, B and C are commonly used. classes D and E are reserved classes, D for multicast groups and E for future purposes.

CLASS A :

  • IP address belonging to class A are assigned to the networks that contain a large number of hosts. Here, class A can support 16 million hosts on 127 networks.
  • Here, the network ID is 8 bits long and the host ID is 24 bits long.
  • IP addresses belonging to class A ranges from 1.x.x.x – 126.x.x.x
  • Default Subnet Mask: 255.x.x.x

Number Of Hosts and Networks:

Number of Hosts: (2^24)-2= 16,777,214 i.e 16 million hosts
Number of Networks: (2^7)-2=126 
Note: Reducing 2 because, 0.0.0.0 and 127.a.b.c are different addresses

>> The range of class A is 1.0.0.1 to 126.255.255.254

Other classes

Class B: 128.1.0.1 to 191.255.255.254
Class C: 192.0.1.1 to 223.255.254.254
Class D: 244.0.0.0 to 239.255.255.255
Class E: 244.0.0.0 to 254.255.255.254

References: https://www.geeksforgeeks.org/introduction-of-classful-ip-addressing/ 

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