单项选择题 A server is having problems booting into the operating system. Which of the following can provide important information to begin to troubleshoot the cause?（）

单项选择题 Asystemadministratoristryingtotroubleshootcompanywideemailproblemsthatmayberelated toDNS.WhichofthefollowingnetworktoolswouldbeMOSTusefultodetermineifitisaDNS issue？（）

单项选择题 Theserverroomthatanadministratormanageshasjustcaughtfire.Whichofthefollowingisthe FIRSTthingthattheadministratorshoulddo？（）