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/8 Subnet Mask: 255.0.0.0

A /8 prefix fixes the first 8 bits of the address as the network, leaving 24 bits for hosts. That gives 16,777,216 addresses, of which 16,777,214 can be assigned to hosts. Before CIDR, /8 was the default mask of a Class A network.

CIDR notation/8
Subnet mask255.0.0.0
Wildcard mask0.255.255.255
Binary mask11111111.00000000.00000000.00000000
Hex mask0xFF000000
Total addresses16,777,216
Usable hosts16,777,214

Example: 10.0.0.0/8

  • Network address: 10.0.0.0
  • First usable host: 10.0.0.1
  • Last usable host: 10.255.255.254
  • Broadcast address: 10.255.255.255

When to use a /8 subnet

Very large private networks. 10.0.0.0/8 is the largest private IPv4 range defined by RFC 1918.

Frequently Asked Questions

What is the subnet mask for /8?

The subnet mask for /8 is 255.0.0.0, and its wildcard (inverse) mask is 0.255.255.255.

How many hosts are in a /8?

A /8 contains 16,777,216 addresses. Subtracting the network and broadcast addresses leaves 16,777,214 usable hosts.