The Layer 2 Ethernet switch searches the MAC address table for an entry that matches the destination MAC address of the frame, thereby forwarding the frame from the corresponding interface. If the search fails, the switch will ______.

On the MSR router, if a certain file has been set as the startup file, you can use the ______ command to check whether the setting is correct.

The XYZ company network is shown in the figure.

There is no logical interface configured on the Router; all hosts can communicate normally. Then there are ___ conflict domains in this network. (Please fill in Arabic numerals)

The two branches of XYZ company are located in different regions, and a wide area network connection must be established between them. According to the plan, the WAN adopts the PPP protocol. Considering network security, it is required that password-type message information is not allowed to be transmitted in clear text on the network. Then which PPP authentication protocol should be adopted?

On the MSR router, you can use the ______ command to clear the NAT session table entries.