At which layer of the OSI model dose PPP perform?（）

Three switches are connected to one anther via trunk ports.Assuming the default switch configuration,which switch is elected as the root bridge for the spanning-tree instance of vlan 1?（）

Which address is the IPV6 all-RIP-routers muticast group address that is used by RIPng as the destaion address?（）

How are VTP advertisements delivered to switches across the network?（）

You have been asked to come up with a subnet mask that will allow all three web servers to be on the same network while providing the max number of subnets.Which network address and subnet mask meet this requirement?（）

Which pairing reflects a correct protocol-and-metric relationship?（）

The network administrator cannot to switch 1 over a telnet session,although the hosts attached to switch 1 can ping the interface Fa0/0 of the router.Given the information in the graphic and assuming that the router and switch2 are configured properly,which of the following commands should be issued on switch 1 to correct this problem?（）

Which command is used to display the collection of OSPF link states?（）

If all OSPF routers in a single area are configured with the same priority value,what value dose a router use for the ODPF router ID in the absence of a loopback interface?（）

Which encapsulation type is a Frame Relay encapsulation type that is supported by Cisco routers?（）