Is the Internet Broken Google’s Gmail system, which serves millions of customers around the world, shut down yesterday. Twitter, the micro-blogging service used by tens of millions of people, went off-line last month. It blamed the trouble on a malicious programmer in Russia who was trying to shut down the account of a user in neighboring Georgia. It is astonishing the local actions of a small number of programmers call bring an entire Internet service to its knees, but that have been the case. The Internet as it is set up now operates at three levels. The first is the servers that store data and content for use by customers. Google and other large companies keep massive server farms. These are well-protected from outside programmers by sophisticated software, but clearly that does not always work. The protection devices may fail more and more often as hackers get more skillful. The second part of the Interact is the "pipes" that carry data, video, e-mail messages, and text of websites from companies such as Google, Yahoo!, and Twirler, that make up Interact content and services to customers. Some of these" pipe" providers, specifically telecom and cable companies, are already complaining that the amount of data that they have to move is rising too rapidly for them to accommodate. Video files, which are particularly large, have posed significant problems to cable companies. The last piece of the Interact is the end user, the companies and consumers who have tire PCs. Perversely, these PCs are also the tools by which hackers build malicious code that they send out to compromise the effectiveness of the servers to destroy the data transport system which is at the core of the worldwide web’s operations. The problem of online outages is as old as the internet itself, AOL’s dial-up 56k service would go down regularly in the mid-1990s. The company did not have enough modems to keep up with demand. The Internet for the last decade may not be the Internet for tire future. The prophylactic software that was meant to protect the web is less effective. Like anything else that is used regularly whether it is a car, a light bulb, or a PC, the Internet is going to have to be upgraded more often now. It won’t work every hour of every day anymore. According to the passage, which description about internet is right
A．The internet operates at three levels, all of which are servers kept by internet operators. B．The servers are so well protected that they are seldom hit by hackers. C．The demand for improving protection devices is urgent as hackers get more and more skillful. D．Google and Twitter keep large farms for customers.