Networking is an essential component of modern computing, allowing computers to communicate and share data with each other. Whether you're preparing for system design interviews or simply interested in understanding the fundamentals of networking, this guide will cover everything you need to know, and even go a bit more in-depth.

IP Addresses: The Unique Identifier

Imagine two computers, a client and a server, trying to communicate with each other. Just like sending mail from one house to another, computers need to know each other's addresses to send data. This is where IP (Internet Protocol) addresses come into play.

An IP address is a 32-bit integer that uniquely identifies a machine on the public internet. It is usually represented as four sets of numbers separated by dots, like this: Each set can have a value between 0 and 255, making the maximum value for each set 256. With 32 bits, we can have up to about 4 billion unique public IP addresses.

IPv4 vs IPv6

The 32-bit limitation of IPv4 has led to the development of IPv6, which allows up to 128 bits, providing a vastly larger address space. Despite IPv6 being newer, IPv4 is still widely used today.

Internet Protocol (IP) and Transmission Control Protocol (TCP)

While IP allows us to send data between machines, it doesn't handle everything we need for reliable communication, especially when sending large amounts of data. This is where TCP (Transmission Control Protocol) comes in.

Network Layer: IP Packets

An IP packet consists of a header and data. The header contains metadata about the packet, such as the source and destination IP addresses. This metadata helps routers and other devices on the network route the packet to its intended destination.

Transport Layer: TCP Packets

When sending large amounts of data, we can't fit everything into a single IP packet. TCP breaks down the data into smaller segments, each wrapped in a TCP header. This header includes additional information like sequence numbers, which help the receiving end reassemble the data in the correct order.

Application Layer Protocols: HTTP

At the highest layer of the networking stack is the application layer, where protocols like HTTP (Hypertext Transfer Protocol) operate. HTTP is used for sending and receiving web pages, and it lives on top of both the transport (TCP) and network (IP) layers.


Machines communicate not only through IP addresses but also over specific channels called ports. Ports are identified by a 16-bit number, allowing for up to 65,535 unique ports per machine. Many application layer protocols, like HTTP and HTTPS, have default ports (80 and 443, respectively), which are used if not explicitly specified.

Public vs Private IP Addresses

For a server to be publicly accessible, it needs a public IP address. Client machines, on the other hand, typically use private IP addresses within a local network (LAN). Routers handle the translation between public and private IP addresses, allowing multiple devices to share a single public IP address.

Static vs Dynamic IP Addresses

IP addresses can be either static or dynamic. Static IP addresses do not change, which can be useful for servers that need to be consistently accessible. Dynamic IP addresses, on the other hand, can change over time but can still function perfectly fine thanks to technologies like Dynamic DNS.

Localhost and Port Numbers

When developing or testing applications locally, you often use localhost (IP address followed by a port number to access the server running on your machine. For example, localhost:4200 would point to port 4200 on your local machine.

Port Conflicts

It's important to note that each port can only be used by one application at a time. If a port is already in use, you'll need to choose a different port for your application.


Understanding the basics of networking, from IP addresses and packets to TCP and application layer protocols, is crucial for anyone working in software development or system design. While this guide covers the essentials, there's always more to learn as you delve deeper into the world of networking.

Whether you're preparing for interviews or looking to expand your knowledge, mastering these fundamentals will serve as a solid foundation for understanding more complex networking concepts in the future. Stay tuned for more in-depth guides and tutorials as we continue to explore the fascinating world of networking!