Free Class A Subnetting tutorial, IP Address Subnetting, how to subnet Class A network
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 A 4-bit subnetting tutorial
If we include four bits to the network part from the host part in the second octet, the default subnet mask of a Class A network 255.0.0.0 is changed to 255.240.0.0. The four bits added to the network part from the host part, in the second 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 A network.
Please refer below image.
| SN No | Description | Binaries | Decimal |
|---|---|---|---|
| 1 | Network Address | 00001010.00000000.00000000.00000000 | 10.0.0.0 |
| First IP Address | 00001010.00000000.00000000.00000001 | 10.0.0.1 | |
| Last IP Address | 00001010.00001111.11111111.11111110 | 10.15.255.254 | |
| Broadcast Address | 00001010.00001111.11111111.11111111 | 10.15.255.255 | |
| 2 | Network Address | 00001010.00010000.00000000.00000000 | 10.16.0.0 |
| First IP Address | 00001010.00010000.00000000.00000001 | 10.16.0.1 | |
| Last IP Address | 00001010.00011111.11111111.11111110 | 10.31.255.254 | |
| Broadcast Address | 00001010.00011111.11111111.11111111 | 10.31.255.255 | |
| 3 | Network Address | 00001010.00100000.00000000.00000000 | 10.32.0.0 |
| First IP Address | 00001010.00100000.00000000.00000001 | 10.32.0.1 | |
| Last IP Address | 00001010.00101111.11111111.11111110 | 10.47.255.254 | |
| Broadcast Address | 00001010.00101111.11111111.11111111 | 10.47.255.255 | |
| 4 | Network Address | 00001010.00110000.00000000.00000000 | 10.48.0.0 |
| First IP Address | 00001010.00110000.00000000.00000001 | 10.48.0.1 | |
| Last IP Address | 00001010.00111111.11111111.11111110 | 10.63.255.254 | |
| Broadcast Address | 00001010.00111111.11111111.11111111 | 10.63.255.255 | |
| 5 | Network Address | 00001010.01000000.00000000.00000000 | 10.64.0.0 |
| First IP Address | 00001010.01000000.00000000.00000001 | 10.64.0.1 | |
| Last IP Address | 00001010.01001111.11111111.11111110 | 10.79.255.254 | |
| Broadcast Address | 00001010.01001111.11111111.11111111 | 10.79.255.255 | |
| 6 | Network Address | 00001010.01010000.00000000.00000000 | 10.80.0.0 |
| First IP Address | 00001010.01010000.00000000.00000001 | 10.80.0.1 | |
| Last IP Address | 00001010.01011111.11111111.11111110 | 10.95.255.254 | |
| Broadcast Address | 00001010.01011111.11111111.11111111 | 10.95.255.255 | |
| 7 | Network Address | 00001010.01100000.00000000.00000000 | 10.96.0.0 |
| First IP Address | 00001010.01100000.00000000.00000001 | 10.96.0.1 | |
| Last IP Address | 00001010.01101111.11111111.11111110 | 10.111.255.254 | |
| Broadcast Address | 00001010.01101111.11111111.11111111 | 10.111.255.255 | |
| 8 | Network Address | 00001010.01110000.00000000.00000000 | 10.112.0.0 |
| First IP Address | 00001010.01110000.00000000.00000001 | 10.112.0.1 | |
| Last IP Address | 00001010.01111111.11111111.11111110 | 10.127.255.254 | |
| Broadcast Address | 00001010.01111111.11111111.11111111 | 10.127.255.255 | |
| 9 | Network Address | 00001010.10000000.00000000.00000000 | 10.128.0.0 |
| First IP Address | 00001010.10000000.00000000.00000001 | 10.128.0.1 | |
| Last IP Address | 00001010.10001111.11111111.11111110 | 10.143.255.254 | |
| Broadcast Address | 00001010.10001111.11111111.11111111 | 10.143.255.255 | |
| 10 | Network Address | 00001010.10010000.00000000.00000000 | 10.144.0.0 |
| First IP Address | 00001010.10010000.00000000.00000001 | 10.144.0.1 | |
| Last IP Address | 00001010.10011111.11111111.11111110 | 10.159.255.254 | |
| Broadcast Address | 00001010.10011111.11111111.11111111 | 10.159.255.255 | |
| 11 | Network Address | 00001010.10100000.00000000.00000000 | 10.160.0.0 |
| First IP Address | 00001010.10100000.00000000.00000001 | 10.160.0.1 | |
| Last IP Address | 00001010.10101111.11111111.11111110 | 10.175.255.254 | |
| Broadcast Address | 00001010.10101111.11111111.11111111 | 10.175.255.255 | |
| 12 | Network Address | 00001010.10110000.00000000.00000000 | 10.176.0.0 |
| First IP Address | 00001010.10110000.00000000.00000001 | 10.176.0.1 | |
| Last IP Address | 00001010.10111111.11111111.11111110 | 10.191.255.254 | |
| Broadcast Address | 00001010.10111111.11111111.11111111 | 10.191.255.255 | |
| 13 | Network Address | 00001010.11000000.00000000.00000000 | 10.192.0.0 |
| First IP Address | 00001010.11000000.00000000.00000001 | 10.192.0.1 | |
| Last IP Address | 00001010.11001111.11111111.11111110 | 10.207.255.254 | |
| Broadcast Address | 00001010.11001111.11111111.11111111 | 10.207.255.255 | |
| 14 | Network Address | 00001010.11010000.00000000.00000000 | 10.208.0.0 |
| First IP Address | 00001010.11010000.00000000.00000001 | 10.208.0.1 | |
| Last IP Address | 00001010.11011111.11111111.11111110 | 10.223.255.254 | |
| Broadcast Address | 00001010.11011111.11111111.11111111 | 10.223.255.255 | |
| 15 | Network Address | 00001010.11100000.00000000.00000000 | 10.224.0.0 |
| First IP Address | 00001010.11100000.00000000.00000001 | 10.224.0.1 | |
| Last IP Address | 00001010.11101111.11111111.11111110 | 10.239.255.254 | |
| Broadcast Address | 00001010.11101111.11111111.11111111 | 10.239.255.255 | |
| 16 | Network Address | 00001010.11110000.00000000.00000000 | 10.240.0.0 |
| First IP Address | 00001010.11110000.00000000.00000001 | 10.240.0.1 | |
| Last IP Address | 00001010.11111111.11111111.11111110 | 10.255.255.254 | |
| Broadcast Address | 00001010.11111111.11111111.11111111 | 10.255.255.255 |
The network 10.0.0.0 is divided into sixteen subnets, each subnet has 1,0485,76 total IPv4 addresses and 1,048,574 usable IPv4 addresses. Two IPv4 addresses are used in each subnet to represent the network address and directed broadcast address (first and last IPv4 addresses in a subnet block). As mentioned in previous subnetting tutorial lessons, you cannot use network address or directed broadcast address as the IPv4 address for devices inside your network. The subnet mask to use for 4-bit subnetting for a Class A network is 255.240.0.0.
Class A IPv4 Subnetting can be summerized as below.
| Subnet Bits | Subnet Mask | CIDR | Total Subnets | Usable IP Address/Subnet |
|---|---|---|---|---|
| 0 | 255.0.0.0 | /8 | 1 | 16777214 |
| 1 | 255.128.0.0 | /9 | 2 | 8388606 |
| 2 | 255.192.0.0 | /10 | 4 | 4194302 |
| 3 | 255.224.0.0 | /11 | 8 | 2097150 |
| 4 | 255.240.0.0 | /12 | 16 | 1048574 |
| 5 | 255.248.0.0 | /13 | 32 | 524286 |
| 6 | 255.252.0.0 | /14 | 64 | 262142 |
| 7 | 255.254.0.0 | /15 | 128 | 131070 |
| 8 | 255.255.0.0 | /16 | 256 | 65534 |
| 9 | 255.255.128.0 | /17 | 512 | 32766 |
| 10 | 255.255.192.0 | /18 | 1024 | 16382 |
| 11 | 255.255.224.0 | /19 | 2048 | 8190 |
| 12 | 255.255.240.0 | /20 | 4096 | 4094 |
| 13 | 255.255.248.0 | /21 | 8192 | 2046 |
| 14 | 255.255.252.0 | /22 | 16384 | 1022 |
| 15 | 255.255.254.0 | /23 | 32768 | 510 |
| 16 | 255.255.255.0 | /24 | 65536 | 254 |
| 17 | 255.255.255.128 | /25 | 131072 | 126 |
| 18 | 255.255.255.192 | /26 | 262144 | 62 |
| 19 | 255.255.255.224 | /27 | 524288 | 30 |
| 20 | 255.255.255.240 | /28 | 1048576 | 14 |
| 21 | 255.255.255.248 | /29 | 2097152 | 6 |
| 22 | 255.255.255.252 | /30 | 4194304 | 2 |
If you practice previous lesson examples and the above example in this lesson, you can clearly understand how to subnet a Class A 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, 14-bit, 15-bit, 17-bit, 18-bit, 19-bit, 20-bit, 21-bit and 22-bit Class A subnets.
In this Class A Subnetting Tutorial - Part 2, You have learned how to perform a Class A 4 bit subnetting. Click "Next" to continue.