📡 Paper 1 · 1.2 Communication and Internet Technologies
1.2.9 Cloud Computing and Internet Services
Cambridge 9618 · International A Level Computer Science · ~14 min read
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Cloud Computing

Cloud computing means storing and processing data on remote servers (owned by a third party) accessed over the internet, rather than on local hardware. Resources are available on demand from anywhere with internet access.

Service models — IaaS, PaaS, SaaS

ModelStands forWhat's providedExample
IaaSInfrastructure as a ServiceVirtual hardware: servers, storage, networking. Customer manages OS, middleware, apps.AWS EC2, Microsoft Azure VMs, Google Compute Engine
PaaSPlatform as a ServiceHardware + OS + development environment. Customer manages apps and data only.Google App Engine, Heroku, Azure App Service
SaaSSoftware as a ServiceComplete application delivered over the internet. Customer just uses the software.Google Docs, Microsoft 365, Dropbox, Salesforce

Memory tip: IaaS = bottom (hardware) → PaaS = middle (platform) → SaaS = top (complete application)

Advantages of cloud computing

  • Scalability — resources can be scaled up or down on demand without buying new hardware
  • Cost — pay-as-you-go; no large upfront hardware investment; reduced maintenance costs
  • Accessibility — data and applications accessible from any device with internet access
  • Automatic updates — provider manages hardware and software updates
  • Reliability/redundancy — providers offer high uptime SLAs; data backed up across multiple data centres
  • Collaboration — multiple users can work on documents simultaneously

Disadvantages of cloud computing

  • Internet dependency — no internet = no access
  • Security concerns — data stored on third-party servers; risk of unauthorised access or breaches
  • Privacy — data outside your physical control; subject to laws of host country
  • Vendor lock-in — difficult to migrate data/services to a different provider
  • Ongoing costs — subscription costs accumulate; can exceed traditional costs long-term
  • Latency — network delays may be unacceptable for real-time applications

Internet Services

World Wide Web (WWW)

A system of interlinked hypertext documents accessed via the internet using HTTP/HTTPS. Web pages are stored on web servers; web browsers retrieve and display them. The WWW is a service that runs over the internet — the internet is the infrastructure; the web is one of many services using it.

Email

Electronic mail uses SMTP to send and POP3/IMAP to receive (covered in 1.2.4). Email servers store messages until retrieved by the client.

FTP (File Transfer Protocol)

Used to transfer files between computers over TCP/IP. FTP uses ports 20 (data) and 21 (control). Not encrypted by default.

VoIP (Voice over IP)

VoIP transmits voice calls as digital packets over the internet (e.g. Skype, WhatsApp calls, Teams). Advantages: cheap/free calls; disadvantages: call quality depends on bandwidth and latency, requires power (no telephony backup).

Streaming

Data (video/audio) is received and displayed in real time without downloading the entire file first. Uses buffering — a small amount stored temporarily to handle network variations. Examples: Netflix, Spotify, YouTube.

Content Delivery Networks (CDNs)

A CDN is a geographically distributed network of servers that deliver web content to users from the server closest to them. Benefits: reduced latency, improved load times, reduced load on origin server, better resilience. Examples: Cloudflare, AWS CloudFront, Akamai.

Exam tip: Cambridge questions often ask students to distinguish IaaS/PaaS/SaaS with examples, or to give advantages and disadvantages of cloud computing. For 6+ mark questions, discuss both benefits AND drawbacks with specific examples. VoIP and streaming may appear as short "describe" questions — include the key technical term (packets, buffering) in your answer.
⚠️ Common Mistakes
  • Confusing the internet and the World Wide Web — the internet is the global network infrastructure; the web is a service that runs over it using HTTP
  • Saying SaaS provides hardware — SaaS provides software only; the provider manages everything underneath
  • Not mentioning "internet dependency" as a disadvantage of cloud computing — always include this
  • Saying VoIP uses circuit switching — VoIP uses packet switching (IP packets)
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Worksheet — 1.2.9 Cloud Computing and Internet Services

8 questions · instantly marked · Cambridge 9618 standard

Q1Explain the difference between IaaS, PaaS, and SaaS, giving one example of each.[6]
✅ Mark scheme
Mark scheme
IaaS — provides virtual hardware (servers, storage, networking); customer manages OS and above; example: AWS EC2 [2]; PaaS — provides hardware + OS + development environment; customer manages only apps and data; example: Google App Engine / Heroku [2]; SaaS — complete software application delivered over internet; customer just uses it; example: Google Docs / Microsoft 365 [2].
Q2State three advantages of cloud computing for a business.[3]
✅ Mark scheme
Mark scheme
1 mark each for any three: scalability — resources can be scaled up/down on demand; reduced costs — no upfront hardware investment, pay-as-you-go; accessibility — data accessible from anywhere with internet; automatic updates by provider; high availability/redundancy; improved collaboration — multiple simultaneous users.
Q3Describe two disadvantages of cloud computing for a business storing sensitive customer data.[4]
✅ Mark scheme
Mark scheme
2 marks each for any two: security risk — data stored on third-party servers increases risk of unauthorised access or data breach [2]; privacy/compliance — data subject to laws of the host country; may be difficult to comply with data protection regulations [2]; internet dependency — no internet access means no access to the data/applications [2]; vendor lock-in — difficult to migrate data/services to a different cloud provider [2].
Q4Describe how streaming video works, including the role of buffering.[4]
✅ Mark scheme
Mark scheme
Video is sent as a continuous stream of data packets from the server [1]; content is displayed in real time as data arrives — the full file does not need to be downloaded first [1]; a buffer temporarily stores a small amount of incoming data [1]; if the network slows temporarily, the buffer provides continuity so playback doesn't pause immediately [1].
Q5Explain how VoIP works and state one advantage and one disadvantage compared to traditional telephony.[4]
✅ Mark scheme
Mark scheme
VoIP converts voice into digital packets and transmits them over the internet using IP protocols [1]; advantage: calls are free/cheap — uses existing internet connection [1]; disadvantage: call quality depends on network bandwidth and latency; requires internet (no calls during outage) [1]. [Award 1 mark for correct explanation of VoIP mechanism].
Q6State the difference between the internet and the World Wide Web.[2]
✅ Mark scheme
Mark scheme
The internet is the global network infrastructure connecting millions of computers worldwide [1]; the World Wide Web is a service/system of interlinked hypertext documents accessed over the internet using HTTP/HTTPS — it is one service that uses the internet [1].
Q7Explain what a CDN (Content Delivery Network) is and state one benefit it provides.[3]
✅ Mark scheme
Mark scheme
A CDN is a geographically distributed network of servers [1] that caches and delivers web content from the server closest to the user [1]; benefit (any one): reduced latency/faster load times; reduced load on origin server; improved resilience — if one server fails, others serve the content [1].
Q8A small startup decides to use SaaS for their productivity tools instead of installing software locally. Evaluate this decision.[6]
✅ Mark scheme
Mark scheme
Advantages: no large upfront software licensing costs — pay monthly/per user [1]; always up to date — provider handles updates automatically [1]; accessible from any device anywhere — supports remote working [1]; scalable — easy to add/remove users as business grows [1]. Disadvantages: internet dependency — no access if connection fails [1]; ongoing subscription cost may exceed one-time licence cost over time [1]; data stored on provider's servers — security and privacy concerns [1]. Conclusion: for a small startup SaaS is likely beneficial due to low initial cost and scalability — accept any reasonable justified conclusion [1]. Maximum 6 marks.
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Mini Test — 1.2.9 Cloud Computing

10 questions · 10 marks · 10 minutes

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