IB Computer Science HL · Year 2 · Lesson 39

Network devices, protocols and TCP/IP model

Networks exist to move data and share resources reliably across connected devices and infrastructures.

Paper 150 minutesA2.1.3 · A2.1.4 · A2.1.5
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Today’s targets

What you need to be able to do

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  • DescribeThe function of network devices
  • DescribeThe network protocols used for transport and application
  • DescribeThe function of the TCP/IP model
A2.1.3A2.1.4A2.1.5
Paper 1 lensMatch the depth of every response to the command term. Previously learned content can move quickly, but retrieval must still be accurate.
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Retrieve

Rapid Recall Deck

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Say the answer aloud before flipping. Mark secure knowledge quickly and spend time on the gaps.

  • What is the main job of a router?: It forwards packets between different networks by choosing an appropriate next route.
  • What is the main job of a switch?: It connects devices within a local network and forwards frames toward the appropriate destination device/port.
  • What do a modem, NIC, and wireless access point do?: A modem adapts signals for an external network link; a NIC provides a device's network interface; a wireless access point connects wireless devices to a network.
  • What is the main difference between TCP and UDP?: TCP provides connection-oriented, ordered, reliable delivery; UDP sends datagrams with lower overhead but without guaranteeing delivery or order.
  • What is the difference between HTTP and HTTPS?: HTTPS is HTTP carried over an encrypted, authenticated TLS connection; HTTP alone does not provide that protection.
  • What does DHCP do?: It automatically supplies network configuration such as IP addressing information to clients.
  • What do a gateway and a hardware firewall do?: A gateway connects or translates between different networks/protocol contexts; a hardware firewall filters network traffic at the network boundary according to security rules.
  • What are the four TCP/IP model layers?: Application, Transport, Internet, and Network Interface.
  • How do TCP/IP layers support network communication?: Each layer provides services to the layer above and adds/uses protocol information so application data can be transported, routed, and transmitted over the physical/network interface.
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A2.1.3 + A2.1.4 · Learn

Core knowledge and application

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A2.1.3Describe

The function of network devices

Networks exist to move data and share resources reliably across connected devices and infrastructures.

Exam moveGive a detailed, accurate account of what happens or what something is like.
Required detail 1Gateways, hardware firewalls, modems, network interface cards, routers, switches, wireless access points
Required detail 2How devices map to the layers of the TCP/IP model

Explain it without notes

Describe: The function of network devices in the context of a school campus connected to cloud services.

  • Gateways, hardware firewalls, modems, network interface cards, routers, switches, wireless access points
  • How devices map to the layers of the TCP/IP model
A2.1.4Describe

The network protocols used for transport and application

Networks exist to move data and share resources reliably across connected devices and infrastructures.

Exam moveGive a detailed, accurate account of what happens or what something is like.
Required detail 1Protocols: transmission control protocol (TCP), user datagram protocol (UDP), hypertext transfer protocol (HTTP), hypertext transfer protocol secure (HTTPS), dynamic host configuration protocol (DHCP)

Explain it without notes

Describe: The network protocols used for transport and application in the context of a school campus connected to cloud services.

  • Protocols: transmission control protocol (TCP), user datagram protocol (UDP), hypertext transfer protocol (HTTP), hypertext transfer protocol secure (HTTPS), dynamic host configuration protocol (DHCP)
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A2.1.5 · Learn

Core knowledge and application

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A2.1.5Describe

The function of the TCP/IP model

Networks exist to move data and share resources reliably across connected devices and infrastructures.

Exam moveGive a detailed, accurate account of what happens or what something is like.
Required detail 1Application, transport, internet, network interface
Required detail 2Role of each layer and the interaction between these layers to ensure reliable data transmission over a network

Explain it without notes

Describe: The function of the TCP/IP model in the context of a school campus connected to cloud services.

  • Application, transport, internet, network interface
  • Role of each layer and the interaction between these layers to ensure reliable data transmission over a network
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Worked model · A2.1.3–A2.1.5

TCP/IP layers, protocols and devices

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ApplicationHTTP / HTTPS / DHCP · user-facing network services
TransportTCP / UDP · end-to-end transport behaviour
InternetIP addressing and routing between networks · routers
Network interfacelocal transmission and access to the medium · NICs / switches / wireless access
Trace a requestA browser requests an HTTPS page. Explain how data moves down the sender’s stack, across the network, and up the receiver’s stack. State where TCP/UDP and IP contribute.

Device reminder

Gateways connect unlike systems/networks; hardware firewalls enforce traffic rules; modems adapt signals for a link; NICs provide network interfaces; routers move packets between networks; switches forward frames within a local network; wireless access points connect wireless devices to the network.

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Apply

Transfer to a new scenario

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ScenarioA school campus connected to cloud services needs a design or technical decision related to today’s topic. Explain what matters and why.
  • Gateways, hardware firewalls, modems, network interface cards, routers, switches, wireless access points
  • How devices map to the layers of the TCP/IP model
  • Protocols: transmission control protocol (TCP), user datagram protocol (UDP), hypertext transfer protocol (HTTP), hypertext transfer protocol secure (HTTPS), dynamic host configuration protocol (DHCP)
  • Application, transport, internet, network interface
  • Role of each layer and the interaction between these layers to ensure reliable data transmission over a network
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Exam lens

Paper 1 practice

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Build the response before checking notesUse precise terminology and match the required depth.
  1. Describe: The function of network devices in the context of a school campus connected to cloud services.
  2. Describe: The network protocols used for transport and application in the context of a school campus connected to cloud services.
  3. Describe: The function of the TCP/IP model in the context of a school campus connected to cloud services.
Self-checkAnswer the exact command term. For explain, include mechanism/reason; for compare, pair criteria; for discuss/evaluate/justify, build supported reasoning and a conclusion.
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Homework

Finish the learning cycle

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IA — main task

Finish Criterion D evidence: development documentation, testing evidence, video planning/recording and full source-code appendix.

Syllabus — short

Complete a short Paper 1 retrieval set based on today’s topic.

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End of Lesson 39.