IPv4 Subnets Explained: Concepts, Examples, and Best Practices

1. What Is an IPv4 Subnet?

An IPv4 subnet is a logical subdivision of an IPv4 network that allows administrators to split a large network into smaller, more manageable segments. Subnetting improves network efficiency, reduces broadcast traffic, and enhances security by isolating network segments.

IPv4 addresses are 32-bit values, typically written in dotted decimal format (e.g., 192.168.1.1). These 32 bits are divided into:

• Network portion

• Host portion

Subnetting works by borrowing bits from the host portion to create additional network identifiers.

2. IPv4 Subnet Masks and CIDR Notation

A subnet mask defines which bits belong to the network and which belong to hosts. It is also a 32-bit number, such as:

• 255.255.255.0 → /24

• 255.255.0.0 → /16

CIDR (Classless Inter-Domain Routing) notation simplifies subnet representation by specifying the number of network bits directly.

Common IPv4 Subnet Examples

Note: In IPv4, the first address is the network address and the last address is the broadcast address, making them unusable for hosts.

3. IPv4 Subnetting Benefits

Subnetting IPv4 networks provides several advantages:

• Efficient use of limited IPv4 address space

• Reduced broadcast domains

• Improved performance and fault isolation

• Easier network management and troubleshooting

4. Private IPv4 Subnet Ranges

Private IPv4 subnets are commonly used in internal networks:

• 10.0.0.0/8

• 172.16.0.0/12

• 192.168.0.0/16

These ranges are not routable on the public internet and are typically used with NAT (Network Address Translation).