What are the methods of subnet masking?

Subnet masking methods primarily revolve around different techniques for configuring subnet masks to divide IP address space into smaller, manageable subnets within a network. The main methods include:

1. Classful Subnetting: Based on the original class-based IP addressing scheme (Class A, B, and C), where subnet masks are predetermined depending on the class of the IP address. Classful subnetting divides IP address ranges into fixed-sized subnets, each with its own subnet mask.
2. Classless Inter-Domain Routing (CIDR): Also known as supernetting, CIDR allows flexible subnetting by specifying a subnet mask using slash notation (e.g., /24). CIDR enables efficient use of IP address space by allowing allocation of variable-sized subnets, accommodating network growth and optimizing address allocation.

Subnetting methods involve techniques for dividing a larger network into smaller subnetworks (subnets) to improve efficiency in IP address allocation and network management. The main methods include:

1. Fixed-Length Subnet Masking (FLSM): In FLSM, each subnet within a network uses the same subnet mask. It involves dividing an IP address range into equal-sized subnets, each with a fixed number of host addresses. FLSM is straightforward but less flexible compared to VLSM.
2. Variable-Length Subnet Masking (VLSM): VLSM allows subnets to use subnet masks of varying lengths, enabling more efficient use of IP address space. With VLSM, larger subnets can be further divided into smaller sub-subnets as needed, optimizing IP address allocation and supporting hierarchical network design.

There are primarily two types of subnet masks based on their length and usage in networking:

1. Default Subnet Mask: Each class of IP address (Class A, B, and C) originally had a default subnet mask assigned to it under the classful addressing scheme. These default subnet masks were predetermined based on the class of the IP address and were used for basic network segmentation.
2. Custom Subnet Mask: With the advent of CIDR and classless addressing, custom subnet masks (also known as variable-length subnet masks, or VLSM) can be configured manually to divide IP address space more flexibly into subnets of varying sizes. Custom subnet masks are specified using CIDR notation (e.g., /24 for a subnet mask of 255.255.255.0), allowing precise control over subnet boundaries and IP address allocation.

Examples of subnet masking involve specifying subnet masks in different notations to define network boundaries and allocate IP addresses effectively within a subnet. For instance:

1. CIDR Notation: Using CIDR notation such as /24 to indicate a subnet mask of 255.255.255.0, which divides an IP address range into subnets each accommodating up to 254 hosts.
2. Dotted-Decimal Notation: Specifying subnet masks in dotted-decimal format like 255.255.248.0, which defines network and host portions of IP addresses for subnetting purposes.
3. Prefix Length Notation: Expressing subnet masks with prefix length notation (e.g., /28) to signify the number of network bits in the subnet mask, facilitating efficient IP address allocation and routing table management.

These examples illustrate different ways subnet masks can be applied to configure and manage IP address space effectively within a network, supporting scalable and organized network architectures.