🌐 Networking Concepts — Core Basics

Ever wondered how your laptop communicates with a website halfway across the globe?
Behind the scenes, networking concepts like IP addresses, subnets, and ports make it all possible. Whether you’re diving into DevOps, cloud computing, or just brushing up your basics, understanding these fundamentals is a must.

In this post, we’ll simplify the core networking concepts—IP Addresses, Subnets & CIDR, and Ports—so that you can grasp them without feeling overwhelmed.

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📍 IP Addresses

An IP address is like a postal address for your device on a network — it uniquely identifies where to send data.

Types of IP addresses

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IPv4 vs IPv6

• IPv4: Most common, e.g., 192.168.0.1

• IPv6: Newer, longer addresses (e.g., 2001:0db8:85a3::8a2e:0370:7334) — designed to solve IPv4 exhaustion.

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🗺️ Subnets & CIDR

What is a subnet?

A subnet divides a big network into smaller parts to:

• Reduce congestion

• Improve security

• Better manage IP allocation

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CIDR notation

CIDR = Classless Inter-Domain Routing.

192.168.1.0/24

• 192.168.1.0 → Network address

• /24 → Number of bits used for the network prefix (remaining bits for hosts)

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How to calculate usable IPs

IPs = 2^(32 - subnet bits) - 2

Example: /24

• Host bits: 32 - 24 = 8

• Usable IPs: 2^8 - 2 = 254

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Visual diagram of /24 subnet

192.168.1.0/24
├─ Network address: 192.168.1.0
├─ First usable:    192.168.1.1
├─ Last usable:     192.168.1.254
└─ Broadcast:       192.168.1.255

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Common subnet sizes

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🚪 Ports

A port is like a door or channel on your device used by different services to communicate.

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Common ports

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Why do we need ports?

A single machine can run multiple services simultaneously — each service listens on a different port, so the OS knows where to route the incoming data.

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Example

ssh user@203.0.113.5

• Uses port 22 by default for SSH.

https://example.com

• Uses port 443 (HTTPS).

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💡 Quick Recap

• IP address: Your device's address on the network.

• Subnet & CIDR: Divide networks and define IP ranges.

• Ports: Entry points for specific services.

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📖 Further Reading

• IANA Service Name and Port Number Registry

• CIDR to IP Range Calculator

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🚀 Wrapping Up

Networking is the foundation of everything we do in the cloud and DevOps world. By understanding IP addresses, subnetting, and ports, you’re building the groundwork for more advanced topics like firewalls, load balancers, and cloud VPCs.

What’s next?
In the next post, we’ll explore Linux fundamentals that every DevOps engineer should know. Stay tuned!