At which layer of the OSI model is RSTP used to prevent loops?（）

Which Cisco IOS diagnostics command can disrupt the operation of a router under high-load conditions?（）

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?（）

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

Which statement describes the rule of split horizon?（）

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

An employee of ABC company has move to an office on a different floor. Although the administrator is able to telnet to all of the routers,the address of Switch F is needed in order to verify that the employee remains in the same VLAN.Which action could be used by the administrator to find the IP address of Switch F?（）

A network administrator is trying to add a new router into an established OSPF network.The networks attached to the new router do not appear in the routing tables of the other OSPF routers.Given the information in the partial configuration shown below,what configuration error is causing this problem?（）Router(config)#router ospf 1Router(config-router)#network 10.0.0.0 255.0.0.0 area 0

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?（）

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