IGCSE Computer Science 0478 — 3.4 Network Hardware Hangman

The 26 key terms

1network

A group of digital systems connected together so they can share data, files, printers and an internet connection. Each connected device is called a node.

2LAN vs WAN

A LAN connects devices in one small area like a home or school. A WAN connects many LANs over a large distance. The internet is the largest WAN.

3network interface

The internal part of a device that lets it send and receive data on a network, using an Ethernet port for wired links or a wireless adapter for Wi-Fi.

40123456789ABCDEF

The 16 hex digits: 0-9, then A=10, B=11, C=12, D=13, E=14, F=15. Each digit stands for one 4-bit value, and F (15) is the largest single hex digit.

5hexadecimal

Base-16 notation that shortens binary so people can read and write it. Used in colour codes, MAC addresses, memory addresses and error codes.

6MAC address

A unique hardware address given to one network interface card (NIC). Each NIC has its own, so a device with Wi-Fi and Ethernet has two. It identifies the hardware, not the network.

7MAC address set at manufacture

A MAC address is set by the manufacturer when the NIC is made and stored in the NIC, so it normally stays the same on any network the device uses.

800:1A:2B:3C:4D:5E

A MAC address is six pairs of hex digits (two digits per pair, 48 bits in total), separated by colons or hyphens, such as 00:1A:2B:3C:4D:5E.

118-bit binary: 128 64 32 16 8 4 2 1

A byte has 8 bits with place values 128 down to 1. Add the place values that are 1s. The smallest number is 0 and the largest is 11111111 = 255, so a byte stores 0 to 255.

12IP address

A unique number that identifies a device on a network, like a postal address, so data knows where to go. IPv4 looks like 192.168.1.5.

13IP address allocation

A device is given its IP address by the network it joins, not by the manufacturer, so it can change on a new network. Unlike a MAC address, it is not built into the NIC.

14IPv4 address

32 bits written as four denary numbers from 0 to 255 separated by full stops, such as 190.0.5.20. Each number is a group of 8 bits.

15invalid IPv4 address

An address without exactly four groups, or with a group outside 0 to 255. Examples: 256.1.1.1 (too big), 192.168.1 (too few groups), 10.-5.2.1 (negative) and 10.a.2.1 (letter).

17IPv6 address

A 128-bit address written as eight groups of four hex digits separated by colons, e.g. 2001:0DB8:0000:0000:0000:FF00:0042:8329

19IPv6

A 128-bit address written in hex with colons. It gives vastly more addresses than 32-bit denary IPv4, which solves the shortage of IPv4 addresses.

20static IP address

An IP address that is set once, usually by hand, and stays the same every time the device connects, so the device always has a predictable address.

21dynamic IP address

An IP address given to a device automatically by the network each time it connects, so it may change and can later be reused by another device.

22static or dynamic IP

Use static for devices others must always find, like web servers and printers; use dynamic for phones and laptops because it needs less set-up work.

23MAC address vs IP address

MAC is fixed by the manufacturer and stays the same, written in hex. IP is given by the network and can change, written in denary (IPv4) or hex (IPv6).

24IP address and MAC address

The IP address shows where a device is on the network so routers can route data to it. The MAC address identifies its physical NIC for local delivery. Both are used to deliver data.

25router

A device that directs data between networks, such as joining a home LAN to the internet and choosing the path data packets take. A home Wi-Fi router also shares the connection wirelessly.

26destination address

The address in a packet header of the device the packet must be delivered to. Routers read it to choose where to send the packet. It is usually an IP address.

27routing

A router reads each packet's destination address in its header and picks the next router to send it to, so every packet's route is decided one step at a time.

28router assigns IP

A router on a local network gives each device that joins its own IP address automatically, so nobody sets it up by hand. Every device gets a different address.

29data path

The route data takes across a network, passing through devices like a router and ISP from the sender to the receiver (a server), then the reply travels back along the route.

30term + because + reason

A full-mark answer uses the correct terms (NIC, MAC address, IP address, router) and links each point to a reason, using 'because'.