A Beginner’s Guide to IP Addresses

Whether you're just starting in cybersecurity or looking to deepen your understanding of how networks operate, IP addresses are at the core of how our digital world communicates. In this post, we’ll break down the theory and structure behind IP addresses, the difference between IPv4 and IPv6, and how NAT (Network Address Translation) helps us stretch a finite resource.

What is an IP Address?

An IP address (short for Internet Protocol address) is a unique identifier that devices use to communicate over a network. If you’ve ever typed ifconfig in a Linux terminal (or ipconfig on Windows), you've seen something like this:

Here’s the key difference:

• IPv4 is written in decimal format, such as 192.168.57.139.

• IPv6 uses hexadecimal format, like fe80::a00:27ff:fe4e:66a1.

How IP Addresses Work (Behind the Scenes)

IPv4 — The OG

IPv4 is based on 32 bits, typically written as four octets separated by dots (e.g., 192.168.1.1). Each octet is 8 bits (1 byte), which makes IPv4 a total of 4 bytes long.

That gives us:

2^32 = 4,294,967,296 possible IPv4 addresses

Not bad... until you realize we’ve pretty much used them all up.

When you see 192.168.1.1, that’s a human-readable form of binary — under the hood, it’s all 1s and 0s. For example, the number 255 in binary is 11111111, which is all 8 bits turned "on".

IPv6 — The Future (Kinda)

IPv6 solves the problem of IPv4 address exhaustion. It uses 128 bits, which gives us:

2^128 = 340 undecillion addresses (that’s 340 followed by 36 zeroes!)

It’s safe to say we’ll never run out in our lifetime. But despite its promise, IPv6 adoption has been slow, and most networks still rely heavily on IPv4.

Public vs. Private IP Addresses

There are two main types of IP addresses:

• Public IP: The address your device uses to communicate with the internet. It’s assigned by your ISP (Internet Service Provider).

• Private IP: The address your device uses within your home or office network. These usually start with:

  • 192.168.x.x

  • 10.x.x.x

  • 172.16.x.x – 172.31.x.x

You might notice that multiple homes can have a device with the same private IP — and that’s totally fine, because of something called NAT.

Why Aren’t We Out of IPv4 Addresses?

Enter NAT (Get it? Like internet… never mind)

NAT(Network Address Translation) allows multiple devices on a private network (like your home) to share a single public IP address. Your router assigns private IP addresses to your devices, such as:

• 192.168.x.x

• 10.x.x.x

• 172.16.x.x – 172.31.x.x

These ranges are designated as private, meaning they’re not routable on the public internet.

Your router then translates these into one public-facing IP address, making it look like all your devices are coming from the same place. That’s why 20+ devices can use the internet in your house, but only need one public IP.

Here are the key private address ranges:

How Do Domain Names Connect to IP Addresses?

You know how you type google.com instead of an IP address?

That’s thanks to DNS (Domain Name System) — the internet’s phonebook. It converts human-readable names like amazon.com into IP addresses that your device can understand and use to connect.

For example, google.com might resolve to something like 142.250.190.78.

Without DNS, we’d have to memorize numbers instead of names — and that would suck.

Static vs. Dynamic IP Addresses

• Static IPs never change — they’re fixed addresses, often used by servers or important systems.

• Dynamic IPs are assigned by DHCP (Dynamic Host Configuration Protocol) and can change over time. Most home networks use these because they’re easier to manage.

For example, your phone might have one IP today, and a different one next week.

Wrapping Up

Understanding IP addressing — especially the difference between IPv4 and IPv6, and the role of NAT — is fundamental for anyone in cybersecurity or networking. As the world evolves and devices multiply, this knowledge will help you troubleshoot networks, secure your systems, and communicate like a pro.