单项选择题 The network administrator has asked you to check the status of the workstation’s IP stack by pinging the loopback address.Which address would you ping to perform this task？（）

多项选择题 The network administrator of the Oregon router adds the follwing command to the router configuration: ip route 192.168.12.0 255.255.255.0 172.16.12.1. What are the results of adding this command?（）

多项选择题 The OSPF hello protocol performs which of the following tasks?（）