A2.1 Network fundamentals: notes and practice

What you need to know

Our summary of the topic in our own words, not the IB guide. Points marked HL are for Higher Level only.

• Explain what a computer network is for and what characterises one
• Distinguish LAN, WAN, PAN and VPN by scale and purpose
• Describe modern digital infrastructures including the internet, cloud, distributed systems, edge computing and mobile networks
• Evaluate the benefits and limitations of a given digital infrastructure for a scenario
• State the function of a router, switch, modem, gateway, network interface card, wireless access point and firewall
• Choose the right network devices for a described network and justify the choice
• Distinguish a protocol from a standard
• Compare TCP and UDP and say when each is the right transport protocol
• Describe the purpose of application protocols including HTTP, HTTPS and DHCP
• Name the four layers of the TCP/IP model and state what each is responsible forHL
• Trace a piece of data down and back up the TCP/IP layers, describing encapsulationHL

Practice questions

Original questions written for the 2027 course, marked as you go. Easiest first.

• Switch, router and wireless access pointWritten · Warm-up
• TCP or UDP for video calls and uploadsWritten · Core
• The four layers of the TCP/IP modelWritten · Core
• Encapsulation through the network layersWritten · Stretch

Exam tips for A2.1

• Know one job for each device in a sentence: a switch forwards frames inside a LAN, a router forwards packets between networks.
• TCP versus UDP is a favourite comparison: reliability and ordering against speed and low overhead.
• For the TCP/IP model, practise describing what gets added at each layer as data goes down the stack.