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 name describes an IPV6 host-enable tunneling technique that uses IPV4 UDP,does not require dedicated gateway tunnels,and can pass through existing IPV4 NAT gateways?（）

What is the subnetwork address for a host with the IP address 201.100.5.68/28?（）

Which command displays the CHAP authentication process as it occurs between two routers?（）

Which IPsec security protocol should be used when confidentiality is required?（）

After the show ip route command has been entered,the follwing routes are displayed.Which route will not be entered into the routing table of a neighboring router?（）

Which cisco ios command can help to determine the timing of various debug events,relative to each other,when you are debugging a complicated router issue?（）

A network administrator needs to configure a serial link between the main office and a remote location.The router at the remote office is a non-cisco router. How should the network administrator configure the serial interface of the main office router to make the connection?（）

Which device might be installed at a branch office to enable and manage an IPsec site-to-site VPN?（）

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