The /24 subnet mask is the default subnet mask for a class C network, which includes all networks from 192.0.0.0 to 223.255.255.0.
/24 subnet mask has a dotted decimal of 255.255.255.0, and this is obtained by converting its binary representation, 11111111.11111111.11111111.00000000, into a dotted decimal.
A /24 subnet mask gives 256 ranges of IP addresses. The first IP address in this range is reserved for the network address, and the last IP address in this range is reserved for the broadcast IP address. Hence, a /24 subnet mask has 254 usable IP addresses.
A /24 subnet can be further subneted with a /25 subnet mask, a /26 subnet subnet, and higher prefix lengths, which we covered earlier.
/24 subnet mask can be used to subnet lower prefix length networks like class B and class A network to divide the network into small networks (subnetworks). For example, a class B network subnet mask with a binary value of 111111111.11111111.00000000.00000000 can be subneted with a /24 subnet mask into 256 subnetworks by borrowing 8 bits from the host bits to add to the network bits to have 11111111.11111111.11111111.00000000.
If we subnet the network; 192.168.0.0/16 which is a class B network with a /24 subnet mask, the network address for the first subnet is 192.168.0.0, the usable IP address range is 192.168.0.1 to 192.168.0.254 and the broadcast IP address is 192.168.0.255. The network address for the second subnet is 192.168.1.0, the usable IP range is 192.168.1.1 to 192.168.1.254 and the broadcast IP address is 192.168.1.255.
Here is a table of IP address of a Class B network subnetted with /24 subnet mask.
| Network Address | Usable IP Range | Broadcast Address |
|---|---|---|
| 192.168.0.0 | 192.168.0.1 to 192.168.0.254 | 192.168.0.255 |
| 192.168.1.0 | 192.168.1.1 to 192.168.1.254 | 192.168.1.255 |
| 192.168.2.0 | 192.168.2.1 to 192.168.2.254 | 192.168.2.255 |
| 192.168.3.0 | 192.168.3.1 to 192.168.3.254 | 192.168.3.255 |
| ... | ... | ... |
| 192.168.252.0 | 192.168.252.1 to 192.168.252.254 | 192.168.252.255 |
| 192.168.253.0 | 192.168.253.1 to 192.168.253.254 | 192.168.253.255 |
| 192.168.254.0 | 192.168.254.1 to 192.168.254.254 | 192.168.254.255 |
| 192.168.255.0 | 192.168.255.1 to 192.168.255.254 | 192.168.255.255 |
/24 Subnet Mask Usable IP Address
In /24 subnet mask, there are 256 ranges of IP addresses; the first IP in this range is reserved for a network address, and the last IP address in this range is reserved as a broadcast IP address. Hence, there are 254 usable IP addresses in the /24 prefix length.
/24 Subnet Mask Dotted Decimal Notation
The dotted decimal notation for a /24 subnet mask is 255.255.255.0. This is gotten by setting the first 24 bits of the 32-bit IPV4 address to “1s” and the remaining 8 bits to “0s.”
Subnetting Class B Network with /24 Subnet Mask
To subnet class B networks with /24 subnet mask, 8 bits are borrowed from the host bits and added to the network bits.
Therefore, a /24 subnet mask will divide a class B network into 256 subnetworks. This value is gotten from the math: 2^8 = 256. Where 8 is the number of borrowed bits.
Subnetting Class A Network with /24 Subnet Mask
To subnet a class A network with a /24 subnet mask, 16 bits need to be borrowed from the host bits and added to the network bits.
Therefore, when a Class A network is subnetted with a /24 subnet mask, it will produce 65536 subnetworks. This value is gotten from the math: 2^16 = 65536. Where 16 is the number of borrowed bits.
How many hosts are in 24?
There are 256 ranges of IP addresses in a /24 prefix length; the first IP address in this range is the network ID, and the last IP address in this range is the broadcast address. Hence, there are 254 IP addresses available to be assigned to a host in a /24 subnet mask.
How Many Subnets in /24
The number of subnetworks in a /24 subnet mask depends on the class of the network being subneted.
Class B networks yield 256 subnetworks, and class A networks yield 65536 subnetworks when subneted with a /24 prefix length.
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