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/28 Subnet Mask: 255.255.255.240

A /28 prefix fixes the first 28 bits of the address as the network, leaving 4 bits for hosts. That gives 16 addresses, of which 14 can be assigned to hosts.

CIDR notation/28
Subnet mask255.255.255.240
Wildcard mask0.0.0.15
Binary mask11111111.11111111.11111111.11110000
Hex mask0xFFFFFFF0
Total addresses16
Usable hosts14

Example: 192.168.1.0/28

  • Network address: 192.168.1.0
  • First usable host: 192.168.1.1
  • Last usable host: 192.168.1.14
  • Broadcast address: 192.168.1.15

When to use a /28 subnet

Very small segments such as a DMZ, a group of network devices, or a few servers. /28 is also the smallest subnet AWS allows in a VPC.

  • 1,048,576 /28 subnets fit in a /8.
  • 4,096 /28 subnets fit in a /16.
  • 16 /28 subnets fit in a /24.

Frequently Asked Questions

What is the subnet mask for /28?

The subnet mask for /28 is 255.255.255.240, and its wildcard (inverse) mask is 0.0.0.15.

How many hosts are in a /28?

A /28 contains 16 addresses. Subtracting the network and broadcast addresses leaves 14 usable hosts.