| How classful (IP) addressing works



Classful addressing divides the IPv4 address space (0.0.0.0-255.255.255.255) into 5 classes: A, B, C, D, and E. However, only A, B, and C are used for network hosts. Class D, which covers the 224.0.0.0-239.255.255.255 IP address range, is reserved for multicasting, and class E (240.0.0.0-255.255.255.255) is reserved for “future use.”


table picture

As we can see, Class A continues to use the first 8-bits of an address, and may be suitable for very large networks. Class B is for networks much smaller than Class A, but still large in their own right. Class C addresses are suitable for small networks.


How to find the Network Id and Host Id of an IP address

Let’s divide this IP address (192.168.1.1) into four sections:

  1. W = 192
  2. X = 168
  3. Y = 1
  4. Z = 1

For finding the Network Id, first we need to know what class of IP address is. so 192.168.1.1 is class “C” because of it starts with 192, (look at the table - Class C is between 192-223)."

"Now that we know our IP is class C and its Network Id has 24 bits which it means W, X and Y are all Network Id.


Host Id

What's left considered the Host Id. So in this case 192.168.1.1 = Z is the Host Id (The last 1).

IP picture

In other words:

IP picture

  • Source: www.auvik.com
  • Wrote: November 22, 2022 | Azar 1, 1401
  • Updated:
  • Posted: November 22, 2022 | Azar 1, 1401