Class C
#Bits
0
1
2
3
4
5
6
Subnet
Mask
255.255.255.0
255.255.255.128
255.255.255.192
255.255.255.224
255.255.255.240
255.255.255.248
255.255.255.252
Effective
Subnets
1
2
4
8
16
32
64
Effective
Hosts
254
126
62
30
14
6
2
If we don’t subnet and use 255.255.255.0 as our subnet mask then we
use all of our IP addresses on one network.
This is not an efficient use of our Class C network.
For each network you loose two IP address, one for the network and
one for the broadcast.
11111111.11111111.11111111.00000000 = 255.255.255.0 = class C mask
11111111.11111111.11111111.11111111 = 255.255.255.255 = broadcast
192.168.100.96
255.255.255.240
192.168.100.97 thru 192.168.100.111 are valid IP address for the 96 network
255.255.255.240 = 11111111.11111111.11111111.11110000
11110000 – 96 network
11110001
11110010
11110011
11110100
11110101
11110110
11110111
11111000
11111001
11111010
11111011
11111100
11111101
11111110
11111111 - broadcast
We’ll use the 192.168.100.0 network
192.168.100.0 is our network and we have 254 total IP addresses
Building C – 40 users – 62 hosts – 255.255.255.192 – subnet 1
Building B – 20 users – 30 hosts – 255.255.255.224 – subnet 2
Building A – 08 users – 14 hosts – 255.255.255.240 – subnet 3
Firewall – 02 users – 04 hosts – 255.255.255.252 – subnet 4
subnet 1
192.168.100.0
255.255.255.192
0 is the network
63 is the broadcast
subnet 2
192.168.100.64
255.255.255.192
64 is the network
95 is the broadcast
subnet 3
192.168.100.96
255.255.255.240
96 is the network
111 is the broadcast
subnet 4
192.168.100.112
255.255.255.252
112 is the network
115 is the broadcast
192.168.100.116
is the next usable network