Calculating IP Address Version (4)
There are four octet in IPV4. Each octet has 8 bits. So, there are 32 bits in IPV4. IPV4 is based on binary (0, 1) and decimal (0 to 9).
| First Octet | Second Octet | Third Octet | Fourth Octet |
|---|---|---|---|
| 8 bits | 8 bits | 8 bits | 8 bits |
| 2726252423222120 | 2726252423222120 | 2726252423222120 | 2726252423222120 |
| 255.255.255.255 | 255.255.255.255 | 255.255.255.255 | 255.255.255.255 |
How to become 255.255.255.255 ? As each octet has 8 bit and is based on binary.... 27 = 128, 26 = 64, 25 = 32, 24 = 16, 23 = 8, 22 = 4, 21 = 2, 20 = 1 128 + 64 + 32 + 16 + 8 + 4 + 2 + 1 = 255
| Decimal | = | Binary | ||||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 1st Octet | 2nd Octet | 3rd Octet | 4th Octet | | 1st Octet | 2nd Octet | 3rd Octet | 4th Octet | ||||||||||
| 192 | . | 168 | . | 1 | . | 0 | | 11000000 | . | 10101000 | . | 00000001 | . | 00000000 |
Let's explore 192.168.1.0/24.... Network Address = 192.168.1.0 Subnet Mask = 255.255.255.0 Usable IP Addresses = 192.168.1.1 to 192.168.1.254 Broadcast Address = 192.168.1.255
Let's explore 192.168.1.0/25.... 1nd Network Address = 192.168.1.0 Subnet Mask = 255.255.255.128 Usable IP Addresses = 192.168.1.1 to 192.168.1.126 Broadcast Address = 192.168.1.127 2nd Network Address = 192.168.1.128 Subnet Mask = 255.255.255.128 Usable IP Addresses = 192.168.1.129 to 192.168.1.254 Broadcast Address = 192.168.1.255
Let's explore 192.168.1.0/26... 1st Network Address = 192.168.1.0 Subnet Mask = 192.168.1.192 Usable IP Addresses = 192.168.1.1 to 192.168.1.62 Broadcast Address = 192.168.1.63 2nd Network Address = 192.168.1.64 Subnet Mask = 192.168.1.192 Usable IP Addresses = 192.168.1.65 to 192.168.1.126 Broadcast Address = 192.168.1.127 3rd Network Address = 192.168.1.128 Subnet Mask = 192.168.1.192 Usable IP Addresses = 192.168.1.129 to 192.168.1.190 Broadcast Address = 192.168.1.191 4th Network Address = 192.168.1.192 Subnet Mask = 192.168.1.192 Usable IP Addresses = 192.168.1.193 to 192.168.1.254 Broadcast Address = 192.168.1.255 (Note: The Subnet Mask is reverse proportional to host range. The larger the subnet mask, the smaller the host range.)
The following table is formula for Ipv4 addresses (Class C). I've made it when I was in Singapore Polytechnic.
| Binary | Decimal | Prefix | Subnet Mask | Count of Networks | Usable IP Range |
|---|---|---|---|---|---|
| - | - | /24 | 255.255.255.0 | 1 | 254 |
| 27 | 128 | /25 | 255.255.255.128 | 2 | 126 |
| 26 | 64 | /26 | 255.255.255.192 | 4 | 62 |
| 25 | 32 | /27 | 255.255.255.224 | 8 | 30 |
| 24 | 16 | /28 | 255.255.255.240 | 16 | 14 |
| 23 | 8 | /29 | 255.255.255.248 | 32 | 6 |
| 22 | 4 | /30 | 255.255.255.252 | 64 | 2 |