HTTPfy

/24 subnet mask (255.255.255.0)

A /24 network has 8 host bits, 256 addresses and 254 usable hosts. It is 1 /24 network.

/24 at a glance

Netmask
255.255.255.0
Wildcard mask
0.0.0.255
Hex mask
0xFFFFFF00
Binary mask
11111111.11111111.11111111.00000000
Host bits
8
Total addresses
256
Usable hosts
254 (minus network and broadcast)
Compared with a /24
1 /24 network
Classful equivalent
Class C
Calculate a /24 in the subnet calculator

Typical uses of a /24

The /24 is the default LAN: 256 addresses, 254 usable hosts, and the mask 255.255.255.0 that most home routers ship with. It is also the longest prefix most networks accept in the global BGP table, so it is the smallest block you can announce on the internet. Three /24s are reserved for documentation (RFC 5737).

Well-known /24 blocks

  • 192.0.2.0/24: TEST-NET-1 documentation range (RFC 5737)
  • 198.51.100.0/24: TEST-NET-2 documentation range (RFC 5737)
  • 203.0.113.0/24: TEST-NET-3 documentation range (RFC 5737)
  • 192.0.0.0/24: IETF protocol assignments (RFC 6890)

Example /24 ranges

NetworkNetwork addressFirst usableLast usableBroadcastNext /24
10.0.0.0/24 10.0.0.0 10.0.0.1 10.0.0.254 10.0.0.255 10.0.1.0/24 calculate
172.16.0.0/24 172.16.0.0 172.16.0.1 172.16.0.254 172.16.0.255 172.16.1.0/24 calculate
192.168.1.0/24 192.168.1.0 192.168.1.1 192.168.1.254 192.168.1.255 192.168.2.0/24 calculate
203.0.113.0/24 203.0.113.0 203.0.113.1 203.0.113.254 203.0.113.255 203.0.114.0/24 calculate

How many /24s fit

In aNumber of /24 subnets
/865,536
/16256
/2016

What a /24 contains

Smaller blockHow many
/264
/2816
/2932
/3064
/32256

Splitting a /24

IntoSubnetsUsable hosts each
/252126
/26462
/27830
/281614

/24 in AWS, Azure and Google Cloud

PlatformAllowed subnet sizes/24 allowed?Usable after reservation
AWS VPC/16 to /28 Yes 251 (5 reserved)
Azure VNet/2 to /29 Yes 251 (5 reserved)
Google Cloud VPC/4 to /29 Yes 252 (4 reserved)

Cloud providers reserve addresses in every subnet (first four and the last address (network, VPC router, DNS, future use, broadcast) on AWS), so the usable count there differs from the classic 2^n - 2.