单项选择题 A web server is running correctly but sending a RST packet to any client trying to connect using HTTP on TCP port 80. Which of the following tools should be used to determine the listening port of the web server?（）

单项选择题 A section of the building has been having intermittent connectivity problems lately. An action plan and solution has been created. Which of the following steps would an administrator perform NEXT?（）

单项选择题 Which of the following is used to identify active hosts along with their network addresses?（）