IP ADDRESS DAN SUBNETING

Following is a list of all Class B and C subnet masks and their maximum hosts and subnets. The last two octets (16 bits) of Class B and the last octet (8 bits) of Class C addresses are divided between hosts and subnets. At the end, all Class C masks are shown in more detail.

CLASS B SUBNET MASKS
How 16
Bits Are  Maximum   Maximum
Subnet Mask       Divided   Subnets   Hosts
255.255.192.0      2/14          2    16,382
255.255.224.0      3/13          6     8,190
255.255.240.0      4/12         14     4,094
255.255.248.0      5/11         30     2,046
255.255.252.0      6/10         62     1,022
255.255.254.0      7/9         126       510
255.255.255.0      8/8         254       254
255.255.255.128    9/7         510       126
255.255.255.192   10/6       1,022        62
255.255.255.224   11/5       2,046        30
255.255.255.240   12/4       4,094        14
255.255.255.248   13/3       8,190         6
255.255.255.252   14/2      16,382         2
CLASS C SUBNET MASKS
How 8
Bits Are   Maximum   Maximum
Subnet Mask       Divided    Subnets   Hosts
255.255.255.192    2/6           2        62
255.255.224.224    3/5           6        30
255.255.240.240    4/4          14        14
255.255.248.248    5/3          30         6
255.255.252.252    6/2          62         2

Class C Subnet Masks

The last 8 bits of the mask are divided between subnets and hosts. Using a Class C address, a network administrator has to determine how best to split up the network: more subnets and fewer hosts or more hosts and fewer subnets.

Networks, Subnets and Hosts

An IP address is first divided between networks and hosts. The host bits are further divided between subnets and hosts. See subnet mask.