If during the PPP authentication process, the authenticatee sends the wrong user name and password to the authenticator, what type of message will the authenticator send to the authenticatee?

The IP addresses of the VLANIF interfaces of the same switch cannot be the same.

In the network shown in the figure below, all links are Ethernet links, and all interfaces of all routers run OSPF protocol, how many DRs are elected in the entire network?

The device port running STP protocol is in Forwarding state. Which of the following statements is correct?

Link aggregation is a common technology in enterprise networks. Which of the following descriptions are the advantages of link aggregation technology? (Multiple Choice)