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/30 Subnet Mask: 255.255.255.252

A /30 prefix fixes the first 30 bits of the address as the network, leaving 2 bits for hosts. That gives 4 addresses, of which 2 can be assigned to hosts.

CIDR notation/30
Subnet mask255.255.255.252
Wildcard mask0.0.0.3
Binary mask11111111.11111111.11111111.11111100
Hex mask0xFFFFFFFC
Total addresses4
Usable hosts2

Example: 192.168.1.0/30

  • Network address: 192.168.1.0
  • First usable host: 192.168.1.1
  • Last usable host: 192.168.1.2
  • Broadcast address: 192.168.1.3

When to use a /30 subnet

Two usable hosts. The traditional choice for point-to-point WAN links before /31 subnets were standardized.

  • 4,194,304 /30 subnets fit in a /8.
  • 16,384 /30 subnets fit in a /16.
  • 64 /30 subnets fit in a /24.

Frequently Asked Questions

What is the subnet mask for /30?

The subnet mask for /30 is 255.255.255.252, and its wildcard (inverse) mask is 0.0.0.3.

How many hosts are in a /30?

A /30 contains 4 addresses. Subtracting the network and broadcast addresses leaves 2 usable hosts.