Networks and the internet practice questions.

In January 2022 a volcanic eruption severed the single submarine cable serving Tonga, leaving the country on limited satellite capacity for several weeks. What the event shows about the internet is that

• satellite links can replace submarine cables at an equivalent capacity
• data held abroad is destroyed when a cable connecting to it is cut
• international traffic depends on a small number of physical routes
• the internet was designed so that no single physical failure can ever isolate a country

Answer: international traffic depends on a small number of physical routes

Almost all intercontinental traffic travels through submarine cables, and redundancy is a matter of how many cables an economy can justify rather than a guarantee built into the protocols. Routing around damage only works where an alternative physical path exists.

In February 2016 India's telecommunications regulator prohibited operators from charging different data prices according to the content accessed, which ended a scheme that offered a selected set of applications free of data charges. The principle the regulator was protecting is best described as

• the right of users to encrypt the traffic they send
• the obligation of operators to publish measured network speeds
• the duty of platforms to remove unlawful content within a fixed period
• equal treatment of traffic whichever service it carries

Answer: equal treatment of traffic whichever service it carries

Differential pricing lets the operator decide which services are cheap to reach, which is the network neutrality question rather than a content or security question. Supporters of such schemes argue they widen access, and that trade-off between more access and a narrower internet is the examinable tension.

A rural clinic is offered two connections: a geostationary satellite link at 50 Mbit/s with a round-trip delay of about 600 ms, and a fixed wireless link at 20 Mbit/s with a delay of about 25 ms. For live consultations with a specialist the clinic should prefer

• the satellite link, because greater bandwidth always improves live video
• the fixed wireless link, because conversation quality depends on delay
• either link, because the two figures describe the same property
• the satellite link, because delay only affects large file transfers

Answer: the fixed wireless link, because conversation quality depends on delay

Bandwidth sets how much data can flow per second while latency sets how long each exchange takes, and interactive speech breaks down once the round trip approaches half a second. The satellite delay is imposed by the 35 786 km orbit, so no upgrade to capacity removes it.

Before a new national network can be reached from abroad, a country-code domain and a block of internet addresses have to be allocated to it. How is that allocation made?

• The International Telecommunication Union assigns both, because it is the United Nations agency responsible for all forms of communication
• The country's own government assigns both, because names and addresses used inside its territory are a matter of national law
• The largest network operator in the country assigns them to itself and then to its customers
• A non-governmental coordinating body allocates them under contract, working through regional registries

Answer: A non-governmental coordinating body allocates them under contract, working through regional registries

Names and numbers are coordinated by ICANN and the five regional internet registries under contract rather than by treaty, which is why internet governance disputes are argued in a body no electorate chose. Its legitimacy, not its competence, is what governments contest.

A video watched in Nairobi is delivered from a cache held inside a Kenyan network rather than from the publisher's servers in Europe. Which statement best describes what follows?

• The publisher can no longer tell how many people have watched the video at all
• The video falls outside the law of every country, because the file never crosses an international border on its way to the viewer
• It arrives faster and international capacity is spared, but the cache becomes a place where it can be blocked
• The video must be paid for twice, once by the publisher and once by the network operator hosting the cache

Answer: It arrives faster and international capacity is spared, but the cache becomes a place where it can be blocked

Caching content close to users cuts both delay and the expensive international leg, which is why operators host it willingly, and it also concentrates delivery at a national point that a national authority can order to act. Performance and control are bought in the same decision.

A shopper sees the padlock icon in the browser's address bar while paying on an online shop. What does the padlock actually confirm?

• the shop behind the site is honest and will deliver the goods
• traffic between the browser and the site is encrypted in transit
• the site cannot be a phishing copy of another shop
• the shopper's own computer is free of malware

Answer: traffic between the browser and the site is encrypted in transit

The padlock shows an encrypted connection to whatever site the browser reached — nothing more. A fraudulent shop or a convincing phishing copy can present a padlock too, which is exactly why 'padlock = safe' is a dangerous shortcut.