Start Here — Networking 101

What is a Network — in plain English?

A network is just a group of devices that can talk to each other. Think of it like a building's postal system — every office (device) has an address, and there are hallways (cables or Wi-Fi) that carry the mail (data) between them.

The Three Big Building Blocks

LAN vs WAN — What's the difference?

A LAN (Local Area Network) is your building — all the devices on your private network. A WAN (Wide Area Network) is everything outside — the internet, your office in another city, a cloud provider. Your router sits at the boundary between the two.

Wired vs Wireless

Network Devices — What does each one actually do?

Here's every device you'll hear about, explained without jargon:

IP Addresses — The network's postal codes

Every device on a network needs a unique IP address — just like every house needs a unique street address so mail gets delivered to the right place. IP stands for Internet Protocol.

A typical IP address looks like: 192.168.1.10 — four numbers 0–255 separated by dots.

Private vs Public IPs

Subnet Masks — What's the neighborhood?

A subnet mask tells a device which part of an IP address is the "neighborhood" (network) and which part is the "house number" (host). You'll see it written two ways — they mean the same thing:

DHCP — The automatic address giver

DHCP (Dynamic Host Configuration Protocol) automatically assigns IP addresses to devices so you don't have to type one in manually on every laptop and phone. Your router or a server runs DHCP. When your laptop joins the Wi-Fi, it shouts "can someone give me an address?" and the DHCP server replies with an IP, subnet mask, default gateway, and DNS server.

DNS — The internet's phone book

DNS (Domain Name System) translates human-readable names like google.com into IP addresses like 142.250.80.46. Without DNS, you'd have to memorise numbers for every website. Common DNS servers: 8.8.8.8 (Google), 1.1.1.1 (Cloudflare).

How data actually gets from A to B

Data doesn't travel as one big blob — it gets chopped into small chunks called packets. Each packet gets wrapped in addressing information, sent across the network, and reassembled at the other end. Think of it like shipping a large painting in multiple small boxes — each box is labelled, sent separately, and reassembled on arrival.

The journey of a packet — ping google.com

The Envelope Analogy — Encapsulation

At each layer of the OSI model, your data gets wrapped in another "envelope" with addressing for that layer. A switch only looks at the innermost envelope (MAC address). A router opens one more layer to see the IP address. This wrapping and unwrapping process is called encapsulation and decapsulation.

TCP vs UDP — Reliable vs Fast

What every junior network engineer should know on Day 1

You don't need to know everything — but these fundamentals will make your first weeks much smoother:

Core Concepts Checklist

First 5 Commands to Know

Jargon You'll Hear in the First Week

Don't panic if you hear these — check the Jargon Decoder tool for plain-English definitions of 100+ terms. Common first-week words:

uplink trunk port access port demarc latency bandwidth throughput loop spanning tree default gateway subnet VLAN 802.1Q NAT ACL