Free Class B Subnetting Tutorials, How to subnet Class B network, IPv4 address subnetting
This lesson is only a part of a series of IPv4 subnetting lessons. All the basic concepts about subnetting are explained in Class C Subnetting Tutorial - Part 1 lesson. You must visit Class C Subnetting Tutorial - Part 1 lesson to understand the basic concepts of subnetting. Please visit below links in order to learn IPv4 subnetting completely.
• Class C Subnetting Tutorial - Part 1
• Class C Subnetting Tutorial - Part 2
• Class B Subnetting Tutorial - Part 1
• Class B Subnetting Tutorial - Part 2
• Class A Subnetting Tutorial - Part 1
• Class A Subnetting Tutorial - Part 2
• Variable Length Subnet Masking (VLSM)
• Supernetting
Class B 4-bit subnetting tutorial
If we add four bits to the network part from host part in the third octet, for a Class B network, the default subnet mask 255.255.0.0 is changed to 255.255.240.0. The four bits added to the network part from the host part, in the third octet, can have sixteen possible values. Those sixteen possible values are 0000, 0001, 0010, 0011, 0100, 0101, 0110, 0111, 1000, 1001, 1010, 1011, 1100, 1101, 1110 and 1111.
That means, we get sixteen subnets if we do a 4-bit subnetting for a Class B network.
Please refer below image.
| SN No | Description | Binaries | Decimal |
|---|---|---|---|
| 1 | Network Address | 10101100.00010000.00000000.00000000 | 172.16.0.0 |
| First IP Address | 10101100.00010000.00000000.00000001 | 172.16.0.1 | |
| Last IP Address | 10101100.00010000.00001111.11111110 | 172.16.15.254 | |
| Broadcast Address | 10101100.00010000.00001111.11111111 | 172.16.15.255 | |
| 2 | Network Address | 10101100.00010000.00010000.00000000 | 172.16.16.0 |
| First IP Address | 10101100.00010000.00010000.00000001 | 172.16.16.1 | |
| Last IP Address | 10101100.00010000.00011111.11111110 | 172.16.31.254 | |
| Broadcast Address | 10101100.00010000.00011111.11111111 | 172.16.31.255 | |
| 3 | Network Address | 10101100.00010000.00100000.00000000 | 172.16.32.0 |
| First IP Address | 10101100.00010000.00100000.00000001 | 172.16.32.1 | |
| Last IP Address | 10101100.00010000.00101111.11111110 | 172.16.47.254 | |
| Broadcast Address | 10101100.00010000.00101111.11111111 | 172.16.47.255 | |
| 4 | Network Address | 10101100.00010000.00110000.00000000 | 172.16.48.0 |
| First IP Address | 10101100.00010000.00110000.00000001 | 172.16.48.1 | |
| Last IP Address | 10101100.00010000.00111111.11111110 | 172.16.63.254 | |
| Broadcast Address | 10101100.00010000.00111111.11111111 | 172.16.63.255 | |
| 5 | Network Address | 10101100.00010000.01000000.00000000 | 172.16.64.0 |
| First IP Address | 10101100.00010000.01000000.00000001 | 172.16.64.1 | |
| Last IP Address | 10101100.00010000.01001111.11111110 | 172.16.79.254 | |
| Broadcast Address | 10101100.00010000.01001111.11111111 | 172.16.79.255 | |
| 6 | Network Address | 10101100.00010000.01010000.00000000 | 172.16.80.0 |
| First IP Address | 10101100.00010000.01010000.00000001 | 172.16.80.1 | |
| Last IP Address | 10101100.00010000.01011111.11111110 | 172.16.95.254 | |
| Broadcast Address | 10101100.00010000.01011111.11111111 | 172.16.95.255 | |
| 7 | Network Address | 10101100.00010000.01100000.00000000 | 172.16.96.0 |
| First IP Address | 10101100.00010000.01100000.00000001 | 172.16.96.1 | |
| Last IP Address | 10101100.00010000.01101111.11111110 | 172.16.111.254 | |
| Broadcast Address | 10101100.00010000.01101111.11111111 | 172.16.111.255 | |
| 8 | Network Address | 10101100.00010000.01110000.00000000 | 172.16.112.0 |
| First IP Address | 10101100.00010000.01110000.00000001 | 172.16.112.1 | |
| Last IP Address | 10101100.00010000.01111111.11111110 | 172.16.127.254 | |
| Broadcast Address | 10101100.00010000.01111111.11111111 | 172.16.127.255 | |
| 9 | Network Address | 10101100.00010000.10000000.00000000 | 172.16.128.0 |
| First IP Address | 10101100.00010000.10000000.00000001 | 172.16.128.1 | |
| Last IP Address | 10101100.00010000.10001111.11111110 | 172.16.143.254 | |
| Broadcast Address | 10101100.00010000.10001111.11111111 | 172.16.143.255 | |
| 10 | Network Address | 10101100.00010000.10010000.00000000 | 172.16.144.0 |
| First IP Address | 10101100.00010000.10010000.00000001 | 172.16.144.1 | |
| Last IP Address | 10101100.00010000.10011111.11111110 | 172.16.159.254 | |
| Broadcast Address | 10101100.00010000.10011111.11111111 | 172.16.159.255 | |
| 11 | Network Address | 10101100.00010000.10100000.00000000 | 172.16.160.0 |
| First IP Address | 10101100.00010000.10100000.00000001 | 172.16.160.1 | |
| Last IP Address | 10101100.00010000.10101111.11111110 | 172.16.175.254 | |
| Broadcast Address | 10101100.00010000.10101111.11111111 | 172.16.175.255 | |
| 12 | Network Address | 10101100.00010000.10110000.00000000 | 172.16.176.0 |
| First IP Address | 10101100.00010000.10110000.00000001 | 172.16.176.1 | |
| Last IP Address | 10101100.00010000.10111111.11111110 | 172.16.191.254 | |
| Broadcast Address | 10101100.00010000.10111111.11111111 | 172.16.191.255 | |
| 13 | Network Address | 10101100.00010000.11000000.00000000 | 172.16.192.0 |
| First IP Address | 10101100.00010000.11000000.00000001 | 172.16.192.1 | |
| Last IP Address | 10101100.00010000.11001111.11111110 | 172.16.207.254 | |
| Broadcast Address | 10101100.00010000.11001111.11111111 | 172.16.207.255 | |
| 14 | Network Address | 10101100.00010000.11010000.00000000 | 172.16.208.0 |
| First IP Address | 10101100.00010000.11010000.00000001 | 172.16.208.1 | |
| Last IP Address | 10101100.00010000.11011111.11111110 | 172.16.223.254 | |
| Broadcast Address | 10101100.00010000.11011111.11111111 | 172.16.223.255 | |
| 15 | Network Address | 10101100.00010000.11100000.00000000 | 172.16.224.0 |
| First IP Address | 10101100.00010000.11100000.00000001 | 172.16.224.1 | |
| Last IP Address | 10101100.00010000.11101111.11111110 | 172.16.239.254 | |
| Broadcast Address | 10101100.00010000.11101111.11111111 | 172.16.239.255 | |
| 16 | Network Address | 10101100.00010000.11110000.00000000 | 172.16.240.0 |
| First IP Address | 10101100.00010000.11110000.00000001 | 172.16.240.1 | |
| Last IP Address | 10101100.00010000.11111111.11111110 | 172.16.255.254 | |
| Broadcast Address | 10101100.00010000.11111111.11111111 | 172.16.255.255 |
The network 172.16.0.0 is divided into sixteen subnets, each subnet has 4,096 total IPv4 addresses and 4,094 usable IPv4 addresses (two IPv4 addresses are used in each subnet to represent the network address and the directed broadcast address). The subnet mask to use for 4-bit subnetting for a Class B network is 255.255.240.0.
Class B Subnetting can be summerized as below.
| Subnet Bits | Subnet Mask | CIDR | Total Subnets | Usable IP Address/Subnet |
|---|---|---|---|---|
| 0 | 255.255.0.0 | /16 | 1 | 65534 |
| 1 | 255.255.128.0 | /17 | 2 | 32766 |
| 2 | 255.255.192.0 | /18 | 4 | 16382 |
| 3 | 255.255.224.0 | /19 | 8 | 8190 |
| 4 | 255.255.240.0 | /20 | 16 | 4094 |
| 5 | 255.255.248.0 | /21 | 32 | 2046 |
| 6 | 255.255.252.0 | /22 | 64 | 1022 |
| 7 | 255.255.254.0 | /23 | 128 | 510 |
| 8 | 255.255.255.0 | /24 | 256 | 254 |
| 9 | 255.255.255.128 | /25 | 512 | 126 |
| 10 | 255.255.255.192 | /26 | 1024 | 62 |
| 11 | 255.255.255.224 | /27 | 2048 | 30 |
| 12 | 255.255.255.240 | /28 | 4096 | 14 |
| 13 | 255.255.255.248 | /29 | 8192 | 6 |
| 14 | 255.255.255.252 | /30 | 16384 | 2 |
If you practice previous lesson examples and the above example in this lesson, you can clearly understand how to subnet a Class B network. Try to practice and find yourself the network address, usable IPv4 address range and the directed broadcast address of remaining 5-bit and 6-bit, 7-bit, 8-bit, 9-bit, 10-bit, 11-bit, 12-bit, 13-bit and 14-bit Class B subnets.
In this Class B Subnetting tutorial Part - 2, you have learned how perform a Class B 4 bit Subnetting. To view Class A Subnetting Tutorials - Part 1, Click "Next".