Five routers are to be connected in a point-to-point subnet. between each pair of routers, the designers may put a high-speed line, a medium-speed line, a low-speed line, or no line. if it takes 100 ms of computer time to generate and inspect each topology, how long will it take to inspect all of them?

Let assume are lettered A to E in that order. Thus, there will be 10 potential lines: AB, AC, AD, AE, BC, BD, BE, CD, CE and DE. Each of these potential lines has 4 possibilities. Therefore, the total number of topologies is 4¹⁰=1,048,576. 1,048,576. At 100ms it will take 104,857.6 seconds which is slightly above 29 hours to inspect each and one of them.