2009年12月大学英语六级考试模拟考卷(恩波)

　　Then there are significant pockets of cyberspace ----some 5 per cent of all Internet addresses----that are not fully connected to the rest of the net. Dubbed the" dark Internet" ,they are often the result of faulty routers or networks with strict security policies that block traffic.

　　Amongst these dark regions are blocks of seemingly unused Internet addresses that may suddenly and briefly flare into activity. Although this behavior might have an innocent explanation ,it can also hint at dubious activities.

　　A three-year study by online security consultants Arbor Networks revealed that dark Internet addresses can be a source of cyber-attacks and junk email. The study suggests that hackers or spammers hijack routers and use them to create false addresses which are left dormant until the hackers bring them to life to facilitate their nefarious(恶毒的)ends. These dark addresses seem to be multiplying in proportion to the growth of the net, says Arbor Networks' Craig Labovitz.

　　Is the Net Hurting the Environment?

　　Sending an email across the Atlantic Ocean does not burn any jet fuel, but the Internet is not without its own, huge carbon footprint. One estimate suggests it takes a huge 152 billion kilowatt-hours per year just to power the data centers that keep the net running. Add to that the energy used by all the computers and peripherals linked to it and the whole thing could be responsible for as much as 2 per cent of all human-made CO2 emissions, putting it on a par with the aviation industry.

　　The way we use our computers also has an impact. According to Google, the production of the electricity needed for a single Internet search generates 200 milligrams of CO2. This may not sound much, but it adds up:1000 searches produce the same CO2 emissions as an average European car travelling 1 kilometre. Worse, Internet traffic is currently growing at around 50 percent each year. According to the international environmental coalition The Climate Group, total emissions from computers will increase by 380 percent, to the equivalent of 1.4 gigatonnes(十亿吨)of CO2, by 2020.

　　If the IT industry continues with business as usual, there is no question that the Internet's energy consumption will skyrocket, says Bill Weihl, Google's green-energy tsar. As a result, many organizations are turning to so-called green data centers which are far more efficient at cooling computers. At the same time, new computers are becoming more efficient. This has led to the energy needed to send each megabyte of data across the net to fall by about 30 per cent annually, says Jonathan Koomey, an energy expert at the Lawrence Berkeley National Laboratory in Oakland, California.

　　IBM says it is developing carbon-neutral data centres, using a novel form of water cooling which channels the heat given off by chips to provide warmth for nearby homes and offices. In a similar vein, Google has patented the idea of sea-based floating data centres which use wave motion as a power source, while cold water sucked up from the deep ocean could cool the computer chips.