====== IP Subnets (IPv4) ======
[[https://www.iptp.net/en_US/iptp-tools/ip-calculator/|IP Subnet Calculator]]
For an IP Address of 10.10.10.1
^ CIDR Notation ^ Total Hosts ^ Usable Hosts¹ ^ IP Range (Usable) ^ Subnet Mask ^
| /24 | 256 | 254 | 10.10.10.1 - 254 | 255.255.255.0 |
| /25 | 128 | 126 | 10.10.10.1 - 126 | 255.255.255.128 |
| /26 | 64 | 62 | 10.10.10.1 - 62 | 255.255.255.192 |
| /27 | 32 | 30 | 10.10.10.1 - 30 | 255.255.255.224 |
| /28 | 16 | 14 | 10.10.10.1 - 14 | 255.255.255.240 |
| /29 | 8 | 6 | 10.10.10.1 - 6 | 255.255.255.248 |
| /30 | 4 | 2 | 10.10.10.1 - 2 | 255.255.255.252 |
| /31 | 2 | 0 | N/A | 255.255.255.254 |
| /32 | 1 | 0 | N/A | 255.255.255.255 |

¹ Usable number of hosts is always total number of hosts minus 2 - the first IP address in the range is the network address; the last IP address in the range is the broadcast address.

Human readable IP addresses (10.100.101.200) are decimal representations of the binary IP address which consists of 8 ones or zeroes . 8 ones or zeroes . 8 ones or zeroes . 8 ones or zeroes.\\
Example: 11010011.01110101.11101111.00111101\\
Since each of the four segments of the IP address have 8 binary digits (thus the term “octals”) and… \\
since a Class C address is one in which the first 3 octals in the range of addresses never change, then…\\
a Class C address can have no more than 256 nodes in the IP range (because 8 binary digits can only represent values from 0 to 255.

All IP Addresses above are Class C - the first 3 octals stay the same. If an IP range greater than 256 is needed, then the third octal will need to change. These, then are Class B addresses. And the maximum number of hosts is 65,535 (255 x 255)

| /23 | 512 | 510 | 10.10.10.1 - 10.10.11.254 | 255.255.254.0 |
| /22 | 1024 | 1022 | 10.10.8.1 - 10.10.11.254 | 255.255.252.0 |
| /21 | 2048 | 2046 | 10.10.8.1 - 10.10.15.254 | 255.255.248.0 |
|  . . . |||||
| /16 | 65,536 | 65,534 | 10.10.0.1 - 10.10.255.254 | 255.255.0.0 |

Beyond 65,536 hosts in the range, the second octal will need to change; that is Class A which can yield a maximum of 16,581,375 addresses (255 x 255 x 255)