Subnets
Networking
Subnets Mask Cheat Sheet
Subnets Masks and Address Details
| CIDR | Subnet Mask | # of Addresses | Wildcard Mask | Binary Subnet Mask |
|---|---|---|---|---|
| /32 | 255.255.255.255 | 1 | 0.0.0.0 | 11111111.11111111.11111111.11111111 |
| /31 | 255.255.255.254 | 2 | 0.0.0.1 | 11111111.11111111.11111111.11111110 |
| /30 | 255.255.255.252 | 4 | 0.0.0.3 | 11111111.11111111.11111111.11111100 |
| /29 | 255.255.255.248 | 8 | 0.0.0.7 | 11111111.11111111.11111111.11111000 |
| /28 | 255.255.255.240 | 16 | 0.0.0.15 | 11111111.11111111.11111111.11110000 |
| /27 | 255.255.255.224 | 32 | 0.0.0.31 | 11111111.11111111.11111111.11100000 |
| /26 | 255.255.255.192 | 64 | 0.0.0.63 | 11111111.11111111.11111111.11000000 |
| /25 | 255.255.255.128 | 128 | 0.0.0.127 | 11111111.11111111.11111111.10000000 |
| /24 | 255.255.255.0 | 256 | 0.0.0.255 | 11111111.11111111.11111111.00000000 |
| /23 | 255.255.254.0 | 512 | 0.0.1.255 | 11111111.11111111.11111110.00000000 |
| /22 | 255.255.252.0 | 1,024 | 0.0.3.255 | 11111111.11111111.11111100.00000000 |
| /21 | 255.255.248.0 | 2,048 | 0.0.7.255 | 11111111.11111111.11111000.00000000 |
| /20 | 255.255.240.0 | 4,096 | 0.0.15.255 | 11111111.11111111.11110000.00000000 |
| /19 | 255.255.224.0 | 8,192 | 0.0.31.255 | 11111111.11111111.11100000.00000000 |
| /18 | 255.255.192.0 | 16,384 | 0.0.63.255 | 11111111.11111111.11000000.00000000 |
| /17 | 255.255.128.0 | 32,768 | 0.0.127.255 | 11111111.11111111.10000000.00000000 |
| /16 | 255.255.0.0 | 65,536 | 0.0.255.255 | 11111111.11111111.00000000.00000000 |
| /15 | 255.254.0.0 | 131,072 | 0.1.255.255 | 11111111.11111110.00000000.00000000 |
| /14 | 255.252.0.0 | 262,144 | 0.3.255.255 | 11111111.11111100.00000000.00000000 |
| /13 | 255.248.0.0 | 524,288 | 0.7.255.255 | 11111111.11111000.00000000.00000000 |
| /12 | 255.240.0.0 | 1,048,576 | 0.15.255.255 | 11111111.11110000.00000000.00000000 |
| /11 | 255.224.0.0 | 2,097,152 | 0.31.255.255 | 11111111.11100000.00000000.00000000 |
| /10 | 255.192.0.0 | 4,194,304 | 0.63.255.255 | 11111111.11000000.00000000.00000000 |
| /9 | 255.128.0.0 | 8,388,608 | 0.127.255.255 | 11111111.10000000.00000000.00000000 |
| /8 | 255.0.0.0 | 16,777,216 | 0.255.255.255 | 11111111.00000000.00000000.00000000 |
| /7 | 254.0.0.0 | 33,554,432 | 1.255.255.255 | 11111110.00000000.00000000.00000000 |
| /6 | 252.0.0.0 | 67,108,864 | 3.255.255.255 | 11111100.00000000.00000000.00000000 |
| /5 | 248.0.0.0 | 134,217,728 | 7.255.255.255 | 11111000.00000000.00000000.00000000 |
| /4 | 240.0.0.0 | 268,435,456 | 15.255.255.255 | 11110000.00000000.00000000.00000000 |
| /3 | 224.0.0.0 | 536,870,912 | 31.255.255.255 | 11100000.00000000.00000000.00000000 |
| /2 | 192.0.0.0 | 1,073,741,824 | 63.255.255.255 | 11000000.00000000.00000000.00000000 |
| /1 | 128.0.0.0 | 2,147,483,648 | 127.255.255.255 | 10000000.00000000.00000000.00000000 |
| /0 | 0.0.0.0 | 4,294,967,296 | 255.255.255.255 | 00000000.00000000.00000000.00000000 |
Subnet Classes and Addresses
| Class | Starting IP | Ending IP | Subnet Mask | Wildcard Mask |
|---|---|---|---|---|
| A | 10.0.0.0 | 10.255.255.255 | 255.0.0.0 | 0.255.255.255 |
| B | 172.16.0.0 | 172.31.255.255 | 255.240.0.0 | 0.15.255.255 |
| C | 192.168.0.0 | 192.168.255.255 | 255.255.255.0 | 0.0.0.255 |
| D | 224.0.0.0 | 239.255.255.255 | Not used for subnetting | Not used for subnetting |
| E | 240.0.0.0 | 255.255.255.255 | Not used for subnetting | Not used for subnetting |
| Localhost | 127.0.0.0 | 127.255.255.255 | 255.0.0.0 | 0.255.255.255 |
| Zeroconf | 169.254.0.0 | 169.254.255.255 | 255.255.0.0 | 0.0.255.255 |
Terminology
CIDR (Classless Inter-Domain Routing)** notation was developed to provide more granularity than legacy classful addressing. CIDR
notation is expressed as /XX.
Wildcard Mask** indicates which parts of an IP address are available for examination.
Binary Subnet Mask** provides a clear representation of the subnet mask in binary format, illustrating the network and host portions.
IP Address Classes**: Classes A, B, and C are used for unicast addressing. Class D is reserved for multicast, and Class E is reserved for experimental purposes.
Localhost (127.0.0.0/8)** is used for loopback testing within a host.
Zeroconf/Automatic Private IP Addressing (APIPA)**: 169.254.0.0/16 is used for self-assigned addresses when DHCP fails.
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