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

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

On which options are standard access list based?（）

An administrator must assign static IP addresses to the servers in a network.For network 192.168.20.24/29, the router is assigned the first usable host address while the sales server is given the last usable host address. Which of the following should be entered into the IP propertied box for the sales server?（）

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?（）

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?（）

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

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

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?（）