First exams 2027 · SL & HL

A2.1.3 · Network fundamentals

Network Devices

The one blinking box in the corner of a house, usually just called "the router," is often several genuinely different devices bundled into a single physical unit. Knowing what each one actually does is the whole point of this statement.

Core for SL & HL Typically 4–6 marks · AO1 Command term: describe

Explainer

Most home networks are sold as a single box, but that box is doing the job of several logically separate devices at once. Each device type below solves one specific problem, and a real network, even a small home one, needs every single one of these jobs done somewhere.

Explainer

A quick look at the TCP/IP layers

The statement also asks how these devices map onto the layers of the TCP/IP model (Transmission Control Protocol/Internet Protocol), the layered set of rules that describes how data actually moves across a network. The full model itself is covered in more depth at HL. For now, it's enough to know the model has four layers, stacked from the physical connection at the bottom up to the actual application at the top, and that most network devices operate at one specific layer.

Layer (bottom to top)Roughly handles
Network interfaceThe physical connection itself: cabling, signals, and addressing devices on the local network
InternetGetting a packet from one network to another, across the wider internet
TransportMaking sure data actually arrives correctly, in order, between the two end devices
ApplicationThe actual program's own data format, the layer closest to what a user sees

Worked example

Seven devices

Click each device to see what it actually does, and which TCP/IP layer it operates at.

Check your understanding

A hotel's WiFi network has one physical device sitting between the guest rooms' wireless devices and the hotel's own internet service provider. It converts the ISP's incoming DSL signal into digital data, and separately, broadcasts a wireless signal guests can join. Which two device functions is this single physical box actually performing?

Common mistake

A recurring confusion between two devices with genuinely overlapping jobs

RecurringA common weak answer treats "gateway" and "router" as interchangeable, since both sit at the boundary between two networks and both direct traffic across it. The real distinguishing mechanism is protocol translation: a router forwards packets between networks that already speak the same kind of addressing, while a gateway specifically exists to translate between two networks using genuinely different protocols or formats.

✕

Treated as the same device: "A gateway and a router both connect a home network to the internet, so they're basically the same thing." Both do sit at a network boundary, but this misses the actual difference in what each one does there.

✓

Names the real distinction: "A router forwards packets between networks that use the same addressing scheme, choosing the most efficient path. A gateway specifically translates between two networks using different protocols or formats, for example converting between a home network's protocol and a different one used by the internet service provider's own equipment." States what each device actually does differently, not just that they're both "at the boundary."

Revision questions

Past-paper style. Write an answer, then reveal the marking points and mark yourself.

Question 1 · 2 marks

[2]Describe the function of a network interface card (NIC).

Question 2 · 3 marks

[3]Distinguish between the roles of a gateway and a router.

Question 3 · 4 marks

[4]A small office wants to connect its own internal devices together, allow them to share one internet connection, and block unwanted traffic from outside. Identify which network devices are needed, and describe the function each one performs.

Flashcards

Active recall for this statement’s key terms.