If a major world war broke out in the 21st century (let's say for the sake of clarity between the USA and China) what would happen to the internet and global communications we all enjoy?
Would it split in half? Would it carry on in much the same way as today?
Based on a general war:
In theory, the Internet is a decentralized network in which there are multiple routes from computer to computer. Even with widespread destruction - from bomb strikes, sabotage, power outages, whatever, this would remain true. But..
Most Internet bandwidth will come from major PoPs (Point of presences) and their high speed lines, owned by major telcos. So a city may have the vast majority of it's internet traffic going through perhaps 2 or 3 major switch centers. Take these out and most of your bandwidth is gone. Take out the fibres connecting these PoPs and again, you lost most bandwidth. No doubt alternative routes will be found but at a fraction of the bandwidth.
Most of the major sites exist on server farms in data centers. Think Google (including all their services), YouTube, Facebook, Wikipedia, Stack Overflow (the horror!), eCommerce, etc. All based in data canters. In a major war, expect most of these to at least lose power if not physically damaged. So you'd be back to running your own server. Most of what we
If the root DNS system is taken down, then IIRC most of the World Wide Web would also go down.
Most of what we think of as the Internet would probably go down. Network geeks would probably be able to use something based on older pre-Web technologies with much lower bandwidth requirements, but the modern internet (which is far more of a centralized model nowadays) would mostly go down.
Considerable amounts of damage can be done by accident.
Since incidents such as this are not deliberate (on an international scale, they certainly are on a national level), it shows that the internet is at least likely to become a battleground and how easily it can become one.
There will be all the usual denial of service, generic hacking and hijacking, but performed by state rather than (or as well as) private or criminal actors.
It could easily be said that for the duration the internet would be either unusable or fundamentally unsafe to use.
There will also be a vast level of propaganda, it'll be easier than ever to communicate with, and affect the moral of, the citizens of the opposing nations.
Since China's Internet is already heavily regulated and isolated, not much would happen in the internet itself probably.
Physically, a lot of cables could be sabotaged. But since the global communication system is decentralized over many cables and satellites, the important channels would not break down.
The internet would be used heavily for propaganda, the USA would probably also control what is distributed ideology-wise in its sphere of control of the internet.
The major change would be internet becoming intranet. Something like https://pl.wikipedia.org/wiki/Kwangmyong_(intranet)
Of course it would not be so visible in the US, but hey would limit access and reduce risk of being infected and attacked by viruses.
Because nowadays you can create net very easily (with your lightbulb being a Bluetooth device and your fridges having access to Wi-Fi or even being a Wi-Fi router) the government and army would like to lower the chance of cyber attack and sabotage with devices being exposed to internet, that we need to assume, is already full of enemies.
Problem: "I do not know how this affects 'The Internet'."
Query: "How does it affect 'The Internet'?"
Answer: your question cannot be answered. It is much too broad and depends heavily on the premise, which is exceedingly vague
– MichaelK May 22 '17 at 11:29