📡 Paper 1 · 1.2 Communication and Internet Technologies
1.2.8 Network Hardware
Cambridge 9618 · International A Level Computer Science · ~13 min read
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Network Interface Card (NIC)

A Network Interface Card (NIC) is a hardware component that connects a computer to a network. Every NIC has a unique MAC address (48-bit, burned-in at manufacture) used to identify it on a local network. NICs can be wired (Ethernet) or wireless (Wi-Fi).

Hub

A hub is a basic networking device that connects multiple devices in a LAN. When it receives data, it broadcasts it to all ports — every connected device receives the frame, even if it isn't the intended recipient. Hubs operate at the Physical layer (Layer 1) of the TCP/IP model's Network Access layer and have no intelligence.

  • All devices share the same collision domain — only one device can transmit at a time
  • Obsolete — replaced by switches in modern networks

Switch

A switch connects multiple devices in a LAN and is smarter than a hub. It maintains a MAC address table that maps MAC addresses to physical ports. When a frame arrives, the switch reads the destination MAC address and forwards it only to the correct port.

  • Each port is its own collision domain — multiple devices can communicate simultaneously
  • More efficient than a hub — reduces unnecessary network traffic
  • Operates at the Data Link layer (Layer 2) — uses MAC addresses

Router

A router connects two or more networks (e.g. a LAN to the internet). It uses IP addresses to determine the best path for data packets to reach their destination, consulting a routing table.

  • Operates at the Network / Internet layer (Layer 3) — uses IP addresses, not MAC addresses
  • Connects different networks — e.g. home LAN to ISP WAN
  • Provides Network Address Translation (NAT) — allows multiple private devices to share one public IP
  • Can also provide DHCP — dynamically assigning IP addresses to local devices
  • Many home routers combine router + switch + wireless access point in one device

Wireless Access Point (WAP)

A Wireless Access Point (WAP) allows wireless devices to connect to a wired network using Wi-Fi. It transmits and receives radio signals (2.4 GHz or 5 GHz) and bridges wireless devices to the wired LAN.

  • Broadcasts a SSID (Service Set Identifier) — the Wi-Fi network name
  • Enterprise networks have multiple WAPs to cover large areas — devices roam between them
  • Not the same as a router — a WAP doesn't route between networks

Modem

A modem (MOdulator-DEModulator) converts digital signals from a computer into analogue signals for transmission over a telephone line, and converts received analogue signals back into digital. Used to connect to a WAN/internet via DSL or cable.

Bridge

A bridge connects two network segments and uses MAC addresses to filter traffic — only forwarding frames to the segment where the destination device is located. Reduces unnecessary traffic between segments. Operates at Data Link layer (Layer 2).

Repeater

A repeater regenerates and amplifies a signal to extend the range of a network. It operates at the Physical layer (Layer 1) — it does not read addresses, it simply boosts the signal.

Summary table — devices and TCP/IP layers

DeviceLayer (TCP/IP)Addresses usedKey function
HubNetwork Access (Physical)NoneBroadcasts to all ports
SwitchNetwork Access (Data Link)MAC addressForwards to correct port only
RouterInternet (Network)IP addressRoutes between networks
WAPNetwork Access (Physical/Data Link)MAC, SSIDWi-Fi access to wired LAN
BridgeNetwork Access (Data Link)MAC addressConnects/filters two segments
RepeaterNetwork Access (Physical)NoneBoosts signal, extends range
ModemNetwork Access (Physical)NoneConverts digital ↔ analogue
Exam tip: Cambridge frequently asks which layer a device operates at and why. Key distinction: hubs and repeaters are "dumb" (Physical layer, no addresses); switches and bridges use MAC addresses (Data Link); routers use IP addresses (Internet/Network layer). A hub broadcasts to all; a switch uses a MAC table to send only to the correct port.
⚠️ Common Mistakes
  • Confusing a hub and a switch — a hub broadcasts to all ports; a switch sends only to the correct port using a MAC table
  • Saying a router uses MAC addresses — routers use IP addresses; switches use MAC addresses
  • Confusing a WAP and a router — a WAP provides Wi-Fi access to a LAN; a router routes packets between networks
  • Saying a repeater reads addresses — a repeater only regenerates signals at the Physical layer; it has no knowledge of MAC or IP addresses
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Worksheet — 1.2.8 Network Hardware

8 questions · instantly marked · Cambridge 9618 standard

Q1State two differences between a hub and a switch.[4]
✅ Mark scheme
Mark scheme
2 marks for any two differences: A hub broadcasts frames to all ports; a switch uses a MAC address table to send frames only to the correct port [2]; a hub creates one large collision domain; a switch gives each port its own collision domain [2]; a hub is less efficient (more traffic); a switch reduces unnecessary traffic [2]; a hub operates at Physical layer; a switch operates at Data Link layer [2].
Q2Explain what a router does and at which TCP/IP layer it operates.[4]
✅ Mark scheme
Mark scheme
A router connects two or more networks [1] and routes packets between them using IP addresses [1] by consulting a routing table to determine the best path [1]; it operates at the Internet (Network) layer of the TCP/IP model [1].
Q3Describe the function of a Network Interface Card (NIC).[3]
✅ Mark scheme
Mark scheme
A NIC is a hardware component that connects a computer to a network [1]; each NIC has a unique MAC address (48-bit, burned-in at manufacture) [1]; NICs can be wired (Ethernet) or wireless (Wi-Fi) [1].
Q4Explain the difference between a Wireless Access Point (WAP) and a router.[4]
✅ Mark scheme
Mark scheme
A WAP allows wireless devices to connect to a wired LAN via Wi-Fi [1] — it bridges wireless and wired segments but does not route between different networks [1]; a router connects two or more different networks [1] and routes packets between them using IP addresses [1].
Q5State the purpose of a modem and explain why it is needed.[3]
✅ Mark scheme
Mark scheme
A modem converts digital signals from a computer into analogue signals for transmission over a telephone/cable line [1] and converts received analogue signals back into digital [1]; it is needed because telephone lines were designed to carry analogue signals — computers communicate digitally [1].
Q6State the layer at which each device operates and the address type it uses: (a) hub, (b) switch, (c) router.[6]
✅ Mark scheme
Mark scheme
(a) Hub: Physical/Network Access layer — no addresses, broadcasts to all [2]; (b) Switch: Data Link/Network Access layer — uses MAC addresses [2]; (c) Router: Internet/Network layer — uses IP addresses [2].
Q7Explain what a repeater does and why it is needed in large networks.[3]
✅ Mark scheme
Mark scheme
A repeater regenerates and amplifies a network signal [1]; signals weaken (attenuate) over long cable distances [1]; a repeater allows the network to extend beyond the maximum cable length without signal loss [1].
Q8A school has 200 computers across multiple buildings. Describe which networking devices would be needed and why.[4]
✅ Mark scheme
Mark scheme
Switches — to connect computers within each building efficiently using MAC address tables [1]; a router — to connect the school network to the internet [1]; WAPs — to allow wireless devices (tablets/laptops) to connect [1]; repeaters or fibre cable — to extend signals between buildings without attenuation [1].
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Mini Test — 1.2.8 Network Hardware

10 questions · 10 marks · 10 minutes

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