Quick Summary
- IP addresses uniquely identify devices on the internet (WAN) — they can change.
- MAC addresses uniquely identify devices on a local network (LAN) — they never change.
- Device names are human-friendly labels, not used for actual communication.
- Ethernet cables carry electrical signals for wired LANs; fibre optic carries light for fast, secure, long-distance WAN links.
- A WAP lets wireless devices join a LAN; a booster extends signal range.
- A router directs data between networks and assigns IP addresses; a gateway translates between different network types.
- A switch intelligently connects multiple wired devices on a LAN.
- A server is a dedicated computer sharing resources (file, web, print, authentication, application) with clients.
- A web browser locates and displays content from the World Wide Web.
- An ISP is the company that actually connects you to the internet, usually for a fee.
- Search engines crawl, index, and rank web pages so you can find things.
- Filter software uses whitelists/blacklists to block or allow access to sites.
1. Identifying Devices
IP Addresses
Think of an IP address like your postal address — it's how data knows where to be delivered on the wider internet (a Wide Area Network, or WAN). Every device that talks to the internet needs one, otherwise servers wouldn't know where to send the web page, email, or video you requested back to.
IP addresses can be handed out in two ways: manually by a network administrator (fixed, "static" addresses — common for servers that need to always be found at the same place), or automatically by a DHCP server (Dynamic Host Configuration Protocol) — this is what happens most of the time on home Wi-Fi, where your phone or laptop is just given the next available address when it joins.
Here's the catch students often miss: if a device moves to a different network, its IP address changes. Your phone has one IP address on your home Wi-Fi, and a completely different one the moment you connect to a café's Wi-Fi down the road. The device hasn't changed, but which network it belongs to has, so the "postal address" system it's part of is different.
IPv4 — 4 blocks of denary (0-255), separated by full stops
12 . 123 . 225 . 32
8bits 8bits 8bits 8bits
(1 byte)(1 byte)(1 byte)(1 byte)
Total = 32 bits = 4 bytes
Max addresses = 2^32 ~ 4.3 billion
IPv6 — 8 blocks of 4 hex digits, separated by colons
2001:0DB8:3333:4444:5555:6666:7777:8888
each block = 16 bits, x 8 blocks
Total = 128 bits = 16 bytes
Max addresses = 2^128 ~ over 1 billion per person on Earth
Why did we need IPv6?
IPv4 only offers about 4 billion unique addresses. With over 7 billion people, and most of us owning several internet-connected devices (phone, laptop, smart TV, watch...), we ran out of room. IPv6's 128-bit addresses give a practically limitless supply.
Memory Hook
IPv4 = 4 groups of numbers (dot-separated) → think "4 for IPv4". IPv6 = uses hexadecimal and colons, and is the newer, bigger version built to solve IPv4's address shortage.
Practice Question
Q: Why does a laptop's IP address change when it moves from a home network to a school network, even though nothing about the laptop's hardware has changed?
MAC Addresses
MAC address
fingerprint
local
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