As server guy who does not deal with subnet masks on a daily basis, whenever I need to find the mask of a given CIDR, I google for “subnet cheat sheet”. As this blog is meant to be “personal cookbook” first, why not create the cheat sheet right here, I thought. I was able to calculate the no. of hosts in my head upto 8190 🙂
| CIDR | Subnet Mask | Hosts |
|---|---|---|
| /8 | 255.0.0.0 | 16777214 |
| /9 | 255.128.0.0 | 8388606 |
| /10 | 255.192.0.0 | 4194302 |
| /11 | 255.224.0.0 | 2097150 |
| /12 | 255.240.0.0 | 1048574 |
| /13 | 255.248.0.0 | 524286 |
| /14 | 255.252.0.0 | 262142 |
| /15 | 255.254.0.0 | 131070 |
| /16 | 255.255.0.0 | 65534 |
| /17 | 255.255.128.0 | 32766 |
| /18 | 255.255.192.0 | 16382 |
| /19 | 255.255.224.0 | 8190 |
| /20 | 255.255.240.0 | 4094 |
| /21 | 255.255.248.0 | 2046 |
| /22 | 255.255.252.0 | 1022 |
| /23 | 255.255.254.0 | 510 |
| /24 | 255.255.255.0 | 254 |
| /25 | 255.255.255.128 | 126 |
| /26 | 255.255.255.192 | 62 |
| /27 | 255.255.255.224 | 30 |
| /28 | 255.255.255.240 | 14 |
| /29 | 255.255.255.248 | 6 |
| /30 | 255.255.255.252 | 2 |
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