Summary  
This chapter explains how to calculate and apply subnet masks to partition an IP address range into smaller, appropriately sized subnets based on host requirements.  

General domain of usage  
Enterprise network design and management

## Identify the IP Address and Required Subnet Mask

**Start with the IP address:** begin with the IP address you want to divide, such as `192.168.1.0`.

**Determine the number of subnets:** if you need 4 subnets, decide on the appropriate subnet mask to accommodate them.

## Calculate the Number of Subnets

**Formula:** use the formula `2^n - 2` where `n` is the number of bits borrowed from the host portion of the address to determine the number of subnets. For instance, borrowing 2 bits results in 4 subnets.

## Determine Subnet Ranges

**Assign subnet ranges:** using the subnet mask, assign subnet ranges. If your original subnet mask is `255.255.255.0` and you need to create 4 subnets, your new subnet mask would be `255.255.255.192`.

  - `192.168.1.0 – 192.168.1.63` (Subnet 1)
  - `192.168.1.64 – 192.168.1.127` (Subnet 2)
  - `192.168.1.128 – 192.168.1.191` (Subnet 3)
  - `192.168.1.192 – 192.168.1.255` (Subnet 4)



## Configure Devices

**Assign IP addresses:** devices in the HR department could use addresses from `192.168.1.10 – 192.168.1.30` under Subnet 1 to ensure they are logically grouped.

## Testing and Verification

**Connectivity tests:** after configuration, test connectivity to ensure devices within the same subnet can communicate, and verify isolation between subnets if required.

## Document Your Subnets

**Documentation:** always document the subnet ranges, IP addresses, and configuration settings for future reference and troubleshooting.

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Learn about the history and evolution of networking technologies and how modern communication systems rely on networks. This section provides a comprehensive overview of how devices communicate and share resources efficiently across different types of networks.

Discover the fundamental role of IP addressing in identifying devices on a network and how subnetting helps optimize network efficiency. This section covers the basics of IP addressing, introduces subnetting techniques to segment networks, and explores how these concepts contribute to smooth communication across connected devices.

Explore the foundational rules and protocols that govern how data is transmitted and received over networks. This section delves into essential networking models, such as the OSI Model and the TCP/IP Model, while covering widely-used protocols like HTTP, FTP, and DNS. Understanding these protocols ensures that devices communicate effectively, regardless of their underlying technologies, creating seamless interactions between global networks.

Learn how to protect networks from cyber threats by implementing essential security measures. Explore firewalls, intrusion detection systems, and encryption techniques to safeguard data. This section also covers securing both wired and wireless networks, helping you maintain robust network security in various environments.

Discover the essential tools and techniques used to diagnose and resolve network issues. Learn how to identify and address common network problems, monitor performance, and ensure networks are running optimally. This section will also cover best practices for maintaining a network and keeping it secure.

Practical Subnetting Exercises

Identify the IP Address and Required Subnet Mask

Calculate the Number of Subnets

Determine Subnet Ranges

Configure Devices

Testing and Verification

Document Your Subnets