Computers practice questions.

In December 2021 a fault in one region of a large cloud provider took websites, delivery applications and smart home devices offline at the same time. What this event best illustrates is that

• cloud computing removes an organisation's need for physical infrastructure
• encryption failed to protect the data stored in the affected region
• concentrating services on a few providers creates shared points of failure
• the affected organisations had failed to keep any backup copies of their data

Answer: concentrating services on a few providers creates shared points of failure

Renting computing from a small number of providers turns one operator's regional fault into a simultaneous outage for unrelated organisations. Backups and encryption protect data from loss and disclosure, but neither restores availability while the provider is down.

A student writes that storing photographs in the cloud has no environmental cost because nothing physical is involved. The most accurate correction is that

• cloud storage costs no more than the electricity used by the user's own device
• the environmental cost falls entirely on the manufacture of the user's own handset
• the files are compressed on upload, so no further resources are required
• data centres consume electricity, cooling water and land

Answer: data centres consume electricity, cooling water and land

The cloud is a business model layered on buildings full of servers: the IEA put the electricity used by data centres, artificial intelligence and cryptocurrency at around 460 TWh in 2022, almost 2 per cent of global electricity demand. Treating remote storage as immaterial is one of the documented misconceptions in this topic.

A hospital replaces a system that streamed ward camera footage to a remote server with one that analyses each frame on the camera itself and transmits only an alert. Which consequence follows most directly from the change?

• Only the alert travels over the network; the images stay on the camera
• The cameras no longer require a mains electricity supply to operate
• The alerts produced by the cameras become legally binding decisions
• The hospital is exempt from data protection law because processing is local

Answer: Only the alert travels over the network; the images stay on the camera

Processing at the edge changes where the data is handled and cuts the volume sent over the network, which is the direct effect. It does not change the legal status of the footage: patients remain identifiable, so data protection duties still apply.

In 2016 traffic from several hundred thousand home routers, cameras and video recorders was directed at a single infrastructure provider and took major websites offline. The devices had been recruited by trying a short list of factory default passwords that their owners had never changed. Which feature of such devices made an attack of that scale possible?

• They are sold to be plugged in and forgotten, so their settings are never changed and updates are never applied
• They hold far more personal data than a laptop does, which is what made them worth compromising in the first place
• They run no software of their own, so no security measure can be applied to them at all
• They connect through mobile networks rather than fixed lines, which makes them impossible to patch

Answer: They are sold to be plugged in and forgotten, so their settings are never changed and updates are never applied

A connected device with no screen, no owner attention and a default credential is a computer that nobody administers, and there are enough of them for their combined upload capacity to matter. The security problem here is a product design and market problem rather than a fault in any single household.

A manufacturer ties each display and battery to one individual handset by a serial number checked in software, so that a genuine replacement part fitted by an independent shop produces a permanent warning and disables one camera function. What is the effect for the owner?

• The device becomes impossible to repair by anyone, including the manufacturer's own service technicians
• The repair is unaffected in practice, because a warning message has no consequence for how the device is used
• Repair remains possible, but only through the channel that the manufacturer controls and prices
• The owner keeps full control of the device, because the part that was fitted is a genuine one

Answer: Repair remains possible, but only through the channel that the manufacturer controls and prices

Pairing moves the limit on repair from the hardware, where a part either fits or does not, into software the owner cannot change, so the manufacturer keeps a veto over the second-hand and independent repair markets. This is the practice that right-to-repair rules in the EU and several US states have been written to reach.

In December 2023 Tesla recalled just over two million cars in the United States to add safeguards to its driver-assistance software. The fix was delivered as an over-the-air update, and no vehicle visited a workshop. For the people who own these cars, an implication of this way of fixing products is that

• safety defects can no longer occur once a car can receive updates
• owners must approve each change before it can be installed
• the maker keeps shaping how the product behaves long after the sale
• the cars must stay permanently connected to the internet to remain legal

Answer: the maker keeps shaping how the product behaves long after the sale

An over-the-air recall shows that the manufacturer retains write access to the product's behaviour for its whole life — convenient for safety, but it moves control from owner to maker. The mistaken readings are the absolutes: updates neither end defects nor create a legal duty to stay online.