Topic 5: Subnetting

• Subnetting - is the practice of dividing a network into two or smaller networks. It increases routing efficiency, which helps to enhance the security of the network and reduces the size of the broadcast domain.
• IP Subnetting - designates high-order bits from the host as part of the network prefix. This method divides a network into smaller schools.
• IPv4 Subnetting - reduces network traffic by eliminating collision and broadcast traffic and thus improves overall performance
• Subnet Mask - is a 32 bits address used to distinguish between a network address and a host address in IP address.
• Two Types of Subnet Masks

  • Default Subnet Mask
  • Custom Subnet Mask
• Default Subnet Mask - is the number of bits which is reserved by the address class. Using this will accommodate a single network subnet in the relative class.
• Custom Subnet Mask - can be defined by an administrator to accommodate many Network.
• In order to subnet a network, it is important to understand:

  • IP Addressing
  • Subnet Mask
• IP address - is a unique identifier assigned to each device on a network.
• If an IP address is 192.168.1.100 and the subnet mask is 255.255.255.0, the first three octets (192.168.1) represent the network portion and the last octet (100) represents the host portion.
• 2 Subnetting Techniques:

  • VLSM
  • CIDR
• VLSM stands for Variable Length Subnet Masking
• VLSM - which allows for different sized subnets within a larger network. This is useful for networks with varying numbers of devices in different locations.
• CIDR stands for Classless Inter-Domain Routing
• CIDR - which allows for more efficient use of IP addresses by using a variable-length prefix instead of a fixed fixed subnet mask. This allows for more flexibility in network design and can help conserve IP addresses.