Simple And Fast Subnetting IP Address Class A, B & C ~ JFA

As an engineer you demanded to be fast and accurately to calculate an IP Addresses such as Network ID, Broadcast, Available IP, Subnet Mask. Here we will examine the fastest way to know IP Address even when the address is difficult to know the Subnet ID.

Some basic knowledge is required to use this way.
1. Class A IP Address
IP : 0-127
Prefix : /8
Bit : 11111111.00000000.00000000.00000000

2. Class B IP Address
IP : 128-191
Prefix : /16
Bit : 11111111.11111111.00000000.00000000

3. Class C IP Address
IP : 192-223
Prefix : /24
Bit : 11111111.11111111.11111111.00000000

Important to remember that 1s is and Network portion and 0s is Host portions. Every octed is consist 8 bit and sparate by dot. While host portion you can manipulate it and change it as you need depend on your need.

One more thing you need to remember :
1 1 1 1 1 1 1 1
128 192 224 240 248 252 254 255

This is all you need to know what is the subnet mask.

Now we will try some scenario to examine the IP Address.

1. 192.168.131.45/29 (Class C)
=> 29 - 24 = 5 (11111111.11111111.11111111.11111000) = 255.255.255.248 (Netmask)
=> 8-5 = 3 (0s)
=> 2^3 = 2+2+2 = 8 (Size)
192.168.131.45/29 focus on bold and red text.
Since it's class C you can only manipulate bit on 4th octet, so focus on 4th octed.
0, 8, 16, 24, 32, 40, 48,.......X
192.168.131.40/29 (Network)
=> 2^3 - 2 = 6 = 192.168.131.41 - 192.168.131.46 (Available IP)
Broadcast is the last IP in the segment
=> 192.168.131.47 (Broadcast)

2. 172.31.92.1/19 (Class B)
=> 19-16 = 3 (11111111.11111111.11100000.00000000) 255.255.224.0 (Netmask)
=> 8 - 3 = 5 (0s)
=> 2^5 = 32 (Size)
172.31.92.1/19 focus on bold and red text.
Since it's class B you can only manipulate bit on 3th octet, so focus on 3th octed.
0, 32, 64, 96, 128.....X
172.31.64.0/19 (Network)
=> 172.31.95.255 (Broadcast)
=> 2^13-2 = 8190 = 172.31.64.1 - 172.31.95.254 (Available IP)

3. 10.14.5.40/14
=> 14-8 = 6 (11111111.11111100.00000000.00000000) 255.252.0.0 (Netmask)
=> 8-6 = 2 (0s)
=>2^2 = 4 (Size)
10.14.5.40/14 focus on bold and red text.
Since it's class A you can only manipulate bit on 2th octet, so focus on 2th octed.
0, 4, 8, 12, 16, 20....X
10.12.0.0/14 (Network)
=> 10.15.255.255 (Broadcast)
=> 2^18 -2 = 262.142 = 10.12.0.1 - 10.15.255.254 (Available IP)

JFA

Simple And Fast Subnetting IP Address Class A, B & C

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