All tools / Subnet cheat sheet
/30 subnet mask
A /30 block has 4 addresses with the netmask 255.255.255.252. Traditionally used for point-to-point links: two usable addresses.
255.255.255.252| CIDR notation | /30 |
| Netmask | 255.255.255.252 |
| Wildcard mask | 0.0.0.3 |
| Total addresses | 4 |
| Usable hosts | 2 |
| Usable in an AWS subnet | n/a (AWS allows /16 to /28) |
| Example range | 10.0.0.0/30: 10.0.0.0 to 10.0.0.3 |
How /30 fits with other sizes
- A /8 holds 4,194,304 subnets of /30.
- A /16 holds 16,384 subnets of /30.
- A /20 holds 1,024 subnets of /30.
- A /24 holds 64 subnets of /30.
- It splits into 2 subnets of /31.
- It splits into 4 subnets of /32.