THE very thing that makes the Internet a robust system, capable of surviving
lots of random damage, also makes it more susceptible to an intelligent attacker
intent on bringing it down. According to a mathematical model published this
week, if Internet nodes were to start failing at random, 18 per cent could
disappear and most of the Internet would remain connected. But if an intelligent
attacker targeted the most important nodes, the network would quickly break into
isolated fragments and stop functioning.
There are two major classes of networks: exponential and scale-free. In an
exponential network, all the nodes have…
