Communication Layer
IB Syllabus: A2 – Networks
Table of Contents
Overview
The Communication Layer covers how computing devices exchange data across networks, from local connections to the global internet. It includes network design, protocols, data transmission, and security – the principles that underpin every online interaction.
This layer covers all 17 outcomes of A2 (Networks). A2.1.1–A2.1.4, A2.2.1, A2.2.3–A2.2.4, A2.3.1–A2.3.3, A2.4.1, and A2.4.4 are assessed at both SL and HL; A2.1.5, A2.2.2, A2.3.4, A2.4.2, and A2.4.3 are HL only.
Sub-pages
| # | Topic | Syllabus | Key Concepts | Level |
|---|---|---|---|---|
| 1 | Network Fundamentals | A2.1.1, A2.1.2, A2.1.3 | LAN, WAN, PAN, VPN, digital infrastructure, network devices | SL + HL |
| 2 | Protocols and Layers | A2.1.4, A2.1.5 | TCP, UDP, HTTP, HTTPS, DHCP, TCP/IP model (HL) | SL + HL |
| 3 | Network Architecture | A2.2.1, A2.2.2, A2.2.3, A2.2.4 | Star, mesh, hybrid topologies, client-server vs P2P, segmentation, server types (HL) | SL + HL |
| 4 | Data Transmission | A2.3.1, A2.3.2, A2.3.3, A2.3.4 | IP addressing, transmission media, packet switching, static/dynamic routing (HL) | SL + HL |
| 5 | Network Security | A2.4.1, A2.4.2, A2.4.3 | Firewalls, vulnerabilities (HL), countermeasures (HL), NAT | SL + HL |
| 6 | Encryption | A2.4.4 | Symmetric/asymmetric encryption, digital certificates, SSL/TLS | SL + HL |
Teaching Sequence
These topics follow the classroom teaching order (W09, W15, W18–W19), covering network fundamentals through security:
- Network Fundamentals (W09) – Network types, digital infrastructure, and network devices
- Protocols and Layers (W15, W18) – Network protocols and the TCP/IP model
- Network Architecture (W09, W15) – Topologies, networking models, and segmentation
- Data Transmission (W18) – IP addressing, transmission media, and packet switching
- Network Security (W19) – Firewalls, vulnerabilities, and countermeasures
- Encryption (W19) – Symmetric/asymmetric encryption and digital certificates
Learning Objectives
By the end of this topic, you should be able to:
- Describe the purpose and characteristics of networks, including LAN, WAN, PAN, and VPN (A2.1.1)
- Describe the purpose, benefits, and limitations of modern digital infrastructures (A2.1.2)
- Describe the function of network devices: gateways, firewalls, modems, NICs, routers, switches, wireless APs (A2.1.3)
- Describe network protocols used for transport and application: TCP, UDP, HTTP, HTTPS, DHCP (A2.1.4)
- Describe the function of the TCP/IP model and how its layers interact (HL) (A2.1.5)
- Describe the functions and practical applications of star, mesh, and hybrid topologies (A2.2.1)
- Describe the function of servers: DNS, DHCP, file, mail, proxy, web server (HL) (A2.2.2)
- Compare and contrast client-server and peer-to-peer networking models (A2.2.3)
- Explain the concepts and applications of network segmentation: subnetting, VLANs (A2.2.4)
- Describe different types of IP addressing: IPv4, IPv6, public/private, static/dynamic, NAT (A2.3.1)
- Compare types of media for data transmission: fibre optic, twisted pair, wireless (A2.3.2)
- Explain how packet switching is used to send data across a network (A2.3.3)
- Explain how static and dynamic routing move data across LANs (HL) (A2.3.4)
- Discuss the effectiveness of firewalls at protecting a network (A2.4.1)
- Describe common network vulnerabilities: DDoS, malware, MitM, phishing, SQL injection, XSS (HL) (A2.4.2)
- Describe common network countermeasures: IDS, IPS, MFA, VPNs, encrypted protocols (HL) (A2.4.3)
- Describe the process of encryption and digital certificates (A2.4.4)
Connections
- Hardware Layer – Network devices (NICs, routers, switches) are physical hardware; understanding CPU and memory helps explain how routers process packets (A1.1)
- Information Layer – Binary representation underpins how data is encoded for transmission; IP addresses are binary numbers (A1.2)
- Operating Systems Layer – The OS manages networking functions: NIC drivers, TCP/IP stack, firewall, DHCP (A1.3)
- Programming Layer – Network concepts inform file I/O, client-server programming, and exception handling for network errors (B2, B3)
- Applications Layer – Databases and applications rely on networks for client-server access and distributed systems (A3)
- Ethics – Network security raises ethical questions about surveillance, privacy, and responsible disclosure (A4.4)