Communication Layer
IB Syllabus: A2 – Networks
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)