CIDR prefix
/30
255.255.255.252
2 usable hosts · 4 addresses
The mask for /30 is 255.255.255.252 — 4 addresses, 2 usable hosts. The classic router point-to-point link (2 hosts).
Mask
255.255.255.252
Wildcard
0.0.0.3
Addresses
4
Hosts
2
Worked example: 192.168.0.0/30
Network address192.168.0.0/30
Broadcast address192.168.0.3
First host192.168.0.1
Last host192.168.0.2
FAQ — /30
What is the subnet mask for /30?
The subnet mask for /30 is 255.255.255.252 (wildcard: 0.0.0.3). The first 30 bits are the network part, the remaining 2 are the host part.
How many hosts fit in a /30?
A /30 block holds 4 addresses, of which 2 are usable hosts (the network and broadcast addresses are excluded).
How many /30 subnets fit in a /24?
A /24 network divides into 64 /30 subnets.
What is a /30 used for?
The classic router point-to-point link (2 hosts).