You are the network administrator of a branch office of your company. the branch office network is part of a wan that covers most of the united states. the office has two windows 2000 servers, two unix servers, one windows nt server, 90 windows 98 clients, 40 windows 2000 professional clients, and five macintosh clients. users have been complaining that they are unable to access resources over the wan at the main headquarters. you suspect that one of the routers between your office and the main headquarters is not working properly. what tcp/ip utility can you use to see if a router is not working properly?