Table of Contents

Subnetting

Wednesday, 12 October 2022
1-minute read
147 words

Subnetting takes a network and divides it into subnetworks.

Example:

10.0.0.x/24 splits into 10.0.0.0 to 10.0.0.255

10.0.0.x/25 splits the network into two equal subnets: 10.0.0.0 to 10.0.0.127 and 10.0.0.128 to 10.0.0.255

10.0.0.x/26 further splits those two parts into four equal subnets.

Attributes of Subnetting

  • Number of IP addresses

    • How many addresses in the network

  • CIDR/Subnet

    • The subnet mask that divides a network (and its CIDR notation equivalent)

  • Network ID

    • First IP address in each subnet
    • Not allowed to be assigned to a host

  • Broadcast ID

    • Last IP address in each subnet
    • Not allowed to be assigned to a host

  • First Host IP

    • IP address immediately after the Network ID
    • Assignable to host

  • Last Host IP

    • IP address immediately before the Broadcast IP
    • Assignable to host

  • Next Network

    • Network ID of the next subnet
    • This will always be the IP address one after the current subnet's broadcast IP