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

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

Which command encrypts all plaintext passwords?（）

What is the purpose of the cisco Vlan Trunking protocol?（）

A network administrator is planning a network installation for a large organization.The design requires 100 separate subnetworks,so the company has acquired a Class B network address.What subnet mask will provide the 100 subnetworks required, if 500 usable host addresses are required per subnet?（）

Which protocol reduces administrative overhead in a switched network by allowing the configuration of a new VLAN to be distributed to all the switches in a domain?（）

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

A router receives information about network 192.168.10.0/24 from multiple sources.What will the router consider the most reliable information about the path to that network?（）

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?（）