Appendix A
Class C Subnet Mask Cheat Sheet
This cheat sheet can come in handy when working with network addresses and subnet masks. A standard netmask is written 255.255.255.0 which is equivalent to the aggregate /24. Using aggregates has become popular because computer people tend to be lazy and it only requires three keystrokes.
Table A.1
Netmasks and Aggregates
| Netmasks and Aggregates | |||
| Subnet Mask | 255.255.255.0 | Hex Mask | 0xffffff00 |
| Subnet Bits/Aggregate | 24 | Host Bits | 8 |
| Number of Subnets | 1 | Hosts per Subnet | 254 |
| Network Address | Host IP Range | Broadcast Addresses | |
| .0 | .1 - .254 | .255 | |
| Subnet Mask | 255.255.255.128 | Hex Mask | 0xffffff80 |
| Subnet Bits/Aggregate | 25 | Host Bits | 7 |
| Number of Subnets | 2 | Hosts per Subnet | 126 |
| Network Address | Host IP Range | Broadcast Addresses | |
| .0 | .1 - .126 | .127 | |
| .128 | .129 - .254 | ||
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