To create subnetworks you take bits from the host portion of the ip address & reserve them to define the subnet address.
This means fewer bits for hosts, so the more subnets the fewer bits available for defining hosts.
- One for each subnet.
- One for each wide area network connection.
2. Determine the number of required host IDs per subnet:
- One for each TCP/IP.
- One for each router interface.
3. Based on the above requirements, create the following:
- One subnet mask for your entire network.
- A unique subnet ID for each physical segment.
- A range of host IDs for each subnet.