IP addressing is one of the most fundamental concepts in computer networking. Every device connected to a network needs a unique identity to send and receive data, and this identity is provided through an IP address. Whether you are learning networking basics or preparing for network engineer interviews, understanding IP addressing is essential.

This article explains what IP addressing is, its types, IP classes, and real-world examples in a simple and interview-friendly way.

What Is IP Addressing?

IP addressing is a method used to uniquely identify devices on a network. An IP address allows devices such as computers, servers, routers, and mobile devices to communicate with each other over a network.

In simple terms, an IP address works like a home address. Just as a postal address ensures that letters reach the correct destination, an IP address ensures that data packets reach the correct device.

Why IP Addressing Is Important

IP addressing plays a critical role in network communication and management.

It helps to:

  • Identify devices uniquely on a network
  • Enable communication between systems
  • Route data across local and wide-area networks
  • Support network security and access control
  • Troubleshoot network connectivity issues

Without IP addressing, devices would not be able to locate or communicate with each other.

Types of IP Addresses

IP addresses are categorized in multiple ways based on usage, scope, and protocol version.

The most common classification of IP addressing is based on IP versions.

IPv4 Addressing

IPv4 uses a 32-bit address format written in decimal numbers separated by dots.

Example:

  • 192.168.1.1
  • 10.0.0.5

IPv4 provides a limited number of addresses, which led to the development of IPv6.

IPv6 Addressing

IPv6 uses a 128-bit address format written in hexadecimal and separated by colons.

Example:

  • 2001:0db8:85a3::8a2e:0370:7334

IPv6 supports a very large address space and is designed to solve address exhaustion and improve routing efficiency.

Public and Private IP Addresses

IP addresses are also classified based on their accessibility.

Public IP Address

A public IP address is globally unique and accessible over the internet. It is assigned to devices that need to communicate outside a private network.

Example:

  • 8.8.8.8

Public IPs are typically assigned by internet service providers.

Private IP Address

A private IP address is used within internal networks and is not directly accessible from the internet.

Common private IP ranges include:

  • 10.0.0.0 – 10.255.255.255
  • 172.16.0.0 – 172.31.255.255
  • 192.168.0.0 – 192.168.255.255

Private IPs are widely used in homes, offices, and enterprise networks.

Static and Dynamic IP Addresses

IP addresses can also be assigned in two different ways.

Static IP Address

A static IP address remains fixed and does not change over time. It is commonly used for servers, network devices, and systems that require consistent access.

Dynamic IP Address

A dynamic IP address is assigned automatically and can change over time. It is managed using DHCP and is commonly used for end-user devices.

IP Address Classes

Before modern subnetting techniques became common, IPv4 addresses were divided into classes. Understanding IP classes is still important for interviews and networking fundamentals.

Class A IP Addresses

Class A addresses are designed for very large networks.

  • Range: 1.0.0.0 to 126.0.0.0
  • Default subnet mask: 255.0.0.0
  • Supports a large number of hosts

Example:

  • 10.1.2.3

Class B IP Addresses

Class B addresses are used for medium-sized networks.

  • Range: 128.0.0.0 to 191.255.0.0
  • Default subnet mask: 255.255.0.0

Example:

  • 172.16.5.10

Class C IP Addresses

Class C addresses are commonly used in small networks.

  • Range: 192.0.0.0 to 223.255.255.0
  • Default subnet mask: 255.255.255.0

Example:

  • 192.168.1.100

Class D and Class E IP Addresses

These classes serve special purposes.

Class D

Used for multicast communication.

  • Range: 224.0.0.0 to 239.255.255.255

Class E

Reserved for experimental and research purposes.

  • Range: 240.0.0.0 to 255.255.255.255

CIDR and Modern IP Addressing

Classful addressing has largely been replaced by CIDR (Classless Inter-Domain Routing). CIDR allows flexible subnet sizes and efficient IP usage.

Example:

  • 192.168.1.0/24

CIDR improves scalability, routing efficiency, and address management in modern networks.

IP Addressing in Real-World Networks

In practical environments, IP addressing is used everywhere.

Examples include:

  • Assigning IPs to routers and switches
  • Configuring servers and cloud instances
  • Enabling communication in LAN, WAN, and MAN networks
  • Supporting firewall rules and VPN connections
  • Load balancing and high availability setups

IP addressing forms the backbone of network architecture.

Common IP Addressing Interview Questions

Interviewers frequently test IP addressing concepts.

Common questions include:

  • Difference between IPv4 and IPv6
  • Public vs private IP addresses
  • What are IP classes and their ranges
  • What is CIDR notation
  • Difference between static and dynamic IP

Being clear with examples helps answer these confidently.

Conclusion

IP addressing is the foundation of computer networking. From identifying devices to enabling secure communication and efficient routing, IP addresses play a vital role in every network. Understanding IPv4, IPv6, IP classes, and public versus private addressing is essential for both real-world networking and interview preparation. A strong grasp of IP addressing concepts builds confidence in designing, managing, and troubleshooting networks.