Subnet Basics and Subnet Masks

Subnet Basics

• A subnet is a smaller network within a larger network, created by dividing an IP address into two parts: network ID and host ID.
• Subnets are used to organize and structure a network, making it easier to manage and improve communication between devices.

Subnet Mask

• A subnet mask is a 32-bit number that determines the scope of a subnet.
• It is used to differentiate between the network ID and host ID in an IP address.
• The subnet mask is applied to the IP address using a bitwise AND operation.

Subnet Types

• Fixed-Length Subnet Mask (FLSM): uses a fixed subnet mask for all subnets.
• Variable-Length Subnet Mask (VLSM): uses a different subnet mask for each subnet, allowing for more efficient use of IP addresses.

Subnetting Process

1. Determine the number of subnets needed: based on the number of devices and networks required.
2. Determine the number of bits to borrow: from the host ID to create the subnet mask.
3. Create the subnet mask: by setting the borrowed bits to 1.
4. Divide the network into subnets: using the subnet mask to create the subnets.

Subnet Calculations

• Subnet address: the network address of a subnet, calculated by performing a bitwise AND operation on the IP address and subnet mask.
• Broadcast address: the highest address in a subnet, calculated by performing a bitwise OR operation on the IP address and the complement of the subnet mask.
• Number of hosts per subnet: calculated by subtracting the number of subnets from the total number of hosts.

Advantages of Subnetting

• Improved network organization: subnets make it easier to manage and maintain a network.
• Increased security: subnets can be used to isolate sensitive areas of the network.
• Better use of IP addresses: subnetting allows for more efficient use of IP addresses.

Subnet Basics

• A subnet is a smaller network within a larger network, created by dividing an IP address into two parts: network ID and host ID, allowing for better organization and structure of a network.

Subnet Mask

• A subnet mask is a 32-bit number that determines the scope of a subnet, allowing devices to differentiate between the network ID and host ID in an IP address.
• The subnet mask is applied to the IP address using a bitwise AND operation, creating a boundary between the network ID and host ID.

Subnet Types

• Fixed-Length Subnet Mask (FLSM): uses a fixed subnet mask for all subnets, simplifying network design and management.
• Variable-Length Subnet Mask (VLSM): uses a different subnet mask for each subnet, allowing for more efficient use of IP addresses and accommodating networks of varying sizes.

Subnetting Process

• Determine the number of subnets needed based on the number of devices and networks required, ensuring efficient use of IP addresses.
• Determine the number of bits to borrow from the host ID to create the subnet mask, depending on the number of subnets needed.
• Create the subnet mask by setting the borrowed bits to 1, establishing a clear boundary between the network ID and host ID.
• Divide the network into subnets using the subnet mask, creating separate networks for better organization and management.

Subnet Calculations

• The subnet address is the network address of a subnet, calculated by performing a bitwise AND operation on the IP address and subnet mask.
• The broadcast address is the highest address in a subnet, calculated by performing a bitwise OR operation on the IP address and the complement of the subnet mask.
• The number of hosts per subnet is calculated by subtracting the number of subnets from the total number of hosts, ensuring accurate network planning.

Advantages of Subnetting

• Subnetting improves network organization, making it easier to manage and maintain a network by dividing it into smaller, more manageable sections.
• Subnetting increases security by allowing for the isolation of sensitive areas of the network, reducing the risk of unauthorized access.
• Subnetting enables better use of IP addresses, reducing waste and ensuring that IP addresses are allocated efficiently, even in large networks.