The big idea: Digital infrastructure is the shared plumbing that applications are built on top of — networks, servers and services nobody rebuilds each time.
Each kind solves one problem well and brings one cost with it.
The internet is not the web: The internet is the global network of networks — the connections themselves.
The worldwide web is one service running on it, made of pages fetched with HTTP. Email, video calls and games are other services on the same internet.
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The internet
A global network of networks, using agreed protocols so any device can reach any other.
Benefit — near-universal reach, and no single owner.
Limit — speed and reliability vary, and nothing is private unless you encrypt it.
Cloud computing
Renting computing from a provider instead of buying machines.
Benefit — resources on demand, no hardware to maintain.
Limit — you depend on the provider's uptime and your own connection, and costs recur forever.
Distributed systems
Many machines cooperating on one job, with no single machine in charge.
Benefit — no single point of failure, and it scales by adding machines.
Limit — keeping them agreed on the same answer is genuinely hard. A cryptocurrency blockchain is one.
Edge computing
Processing the data where it is produced rather than sending it away first.
Benefit — an answer in milliseconds, and far less data on the network.
Limit — many small machines to maintain, each with limited power. Smart traffic lights work this way.
Mobile networks
Wireless coverage over a wide area, through masts, so devices stay connected while moving.
Benefit — connectivity anywhere there is signal.
Limit — bandwidth is shared with everyone nearby, and coverage has gaps.
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The question is how far the data must travel: Cloud means sending data away to be processed. Edge means processing it where it is.
That single difference decides response time, network load and what happens when the connection drops.
Cloud
- Huge processing power and storage available on demand
- Data travels to the provider and back, so there is delay
- Stops working if the connection is lost
- Right for big jobs that can wait a moment — analysis, backups, training models
Edge
- Limited power in each device, but an answer in milliseconds
- Far less data crosses the network
- Keeps working when the connection is lost
- Right for anything that must react immediately — traffic lights, vehicles, machinery
A traffic light cannot wait: A smart traffic light deciding whether to change must answer in milliseconds, and must keep working if its link fails.
Sending its camera feed to a data centre would be slower, more fragile, and would flood the network. So it processes at the edge.
How this is tested — you must give a benefit AND a limitation, and tie both to the described situation. It comes up two ways:
Paper 1 Section A
- Describe an infrastructure's purpose, benefits and limits, 3-4 marks
- Distinguish two of them
- Say which suits a stated application
Paper 1 Section B — case study
- Identify the infrastructure the case study relies on
- Evaluate whether it is the right choice
The classic trap: Treating "the internet" and "the cloud" as the same thing. The internet is the connection; the cloud is computing rented over it. A question about one is not answered by describing the other.
A city fits its traffic lights with cameras that decide when to change the signals. Describe why edge computing suits this better than cloud computing.
Model answer plan
See the answer broken into clear points, with guidance on how each point earns marks.