I Found These Images Very Helpful
Best Video for Learning Subnetting
Classes
A – Private – Not routable on the internet
- Range: 1-127
- CIDR: /8
- N.H.H.H
- 255.0.0.0
- 0
B
- Range: 128 – 191
- CIDR: /16
- 172.16.0.0 – 172.31.255.255
- N.N.H.H
- 255.255.0.0
- 10
C
- Range: 192 – 223
- CIDR: /24
- 192.168.0.0 – 192.168.255.255
- N.N.N.H
- 255.255.255.0
- 110
Bit Values
128 64 32 16 8 4 2 1
xxxxxxxx.xxxxxxxx.xxxxxxxx.xxxxxxxx
CIDR – how many bits on. each x is a bit
Network is everything that is on.
Host is everything that is off.
Hosts are numbers on the right subtract 2.
Subnets are from left to right and count how many bits.
Example Breakdown:
192.168.100.97 /27
255 . 255 . 255. 111|00000
1 1 1 0 0 0 0 0
|128 64 32|
32 is increment
x.x.x.32
x.x.x.64
x.x.x.96 +31 = 127
96 subnet
broadcast 127
Examples Breakdown:
255.255.254.0
x.x.11111111|0.0
2 4 8 16 32 64 128
512 – 2 = 510
BIT = Decimal
1 = 128
2 = 192
2 = 224
4 = 240
5 = 248
6 = 252
7 = 254
8 = 255
