amazon.co.ukNetworks and Internet
A-Level Computer Science revision: Networks and Internet. Learning objectives, key points, worked examples and practice questions across AQA, Edexcel, OCR, WJEC and CCEA.
📌 Key Points
Key Fact: Topologies: Star (central hub), Mesh (all connected), Bus (shared cable), Ring (token passing)
Key Fact: TCP/IP: App (HTTP, DNS, FTP), Transport (TCP reliable, UDP fast), Internet (IP routing), Link (Ethernet, WiFi)
Key Fact: TCP: 3-way handshake, sequencing, flow control, congestion control; UDP: connectionless, low latency
Key Fact: DNS: hierarchical (root, TLD, authoritative); recursive/iterative queries; records (A, AAAA, MX, CNAME)
Key Fact: IPv4: 32-bit, dotted decimal, classes A/B/C, subnet mask, CIDR (/24); IPv6: 128-bit, hex, no NAT needed
Key Fact: Threats: malware (virus, worm, ransomware), phishing, DoS/DDoS, MITM, SQLi (input sanitisation), XSS (output encoding)
Key Fact: Encryption: Symmetric (AES, same key), Asymmetric (RSA, public/private); TLS: handshake, certificates, CA; Firewall: packet filter, stateful, application; VPN: encrypted tunnel; Auth: MFA, OAuth, JWT
🎯 Learning Objectives
- Compare network topologies: star, mesh, bus, ring, hybrid
- Understand TCP/IP stack: Application, Transport, Internet, Link layers
- Analyse key protocols: HTTP/HTTPS, DNS, TCP, UDP, IP, DHCP, FTP, SSH
- Understand IP addressing: IPv4 (classes, subnetting, CIDR), IPv6
- Describe cybersecurity threats: malware, phishing, DoS, MITM, SQL injection, XSS
- Apply security: encryption (symmetric/asymmetric, TLS/SSL), firewalls, VPNs, authentication
💡 Worked Example
Exam-Style Question
Question: Explain the TLS handshake process
Model Answer:
1. Client hello (supported ciphers). 2. Server hello (chosen cipher) + certificate (public key, CA signed). 3. Client verifies cert (CA trusted, not expired, domain matches). 4. Client generates pre-master secret, encrypts with server public key, sends. 5. Both derive session keys. 6. Encrypted communication begins
❓ Practice Questions
Model answers are being added progressively - questions marked ✗ don't have one yet. Cross-check with your teacher or the official mark scheme.
Questions:
- Subnet 192.168.1.0/24 into 4 subnets✗ answer coming soon
- Compare TCP vs UDP for video streaming✗ answer coming soon
- Explain DNS resolution steps✗ answer coming soon
- Describe SQL injection prevention✗ answer coming soon
- How does RSA key exchange work?✗ answer coming soon
🎬 Video Resources
- Networks and Internet - Overview -- YouTube Search
- Networks and Internet - Exam Questions -- YouTube Search
📄 Past Papers & Exam Resources
🔗 Further Reading & Resources
- Physics & Maths Tutor - Networks and Internet -- Free notes, worksheets, and past paper questions by topic
- Dr Frost Maths - Networks and Internet -- Free resources, slides, and interactive questions
- BBC Bitesize - Networks and Internet -- BBC Bitesize revision resources