What does a unicast prefix-based IPv6 multicast address start with？（）

Choose two commands that are required to enable multicast on a router， when it is known that the receivers use a specific functionality of IGMPv3.（）

You are the network administrator of an enterprise company that just deployed a global IP telephony environment. In order to guarantee good voice quality， you asked your provider to implement QoS on the CE routers of your MPLS network. On your LAN， you have also deployed QoS. Users， however， keep complaining about bad voice quality， and the provider does not see matches on the DSCP values that you have asked him to match upon. What is most likely the problem？（）

For the following ports， which port is on every bridge in a Spanning Tree Protocol IEEE 802.1w network except the root bridge？（）

Which statement is correct about an OSPF sham-link？（）

In GLBP， which router will answer on client ARP requests？（）

Two directly connected routers， R1 and R2， are both configured for OSPF graceful restart. R2 is able to switch packets in hardware， but R1 is not. If a network administrator logs on to R2 and performs a system reload， which will be the result？（）

For the following items，what is the mathematical relationship between the committed information  rate （CIR）， committed burst （Bc）， and committed rate measurement interval （Tc）？（）

Which three protocols should be explicitly managed by using Control Plane Policing on an Internet border router？（）

Which IOS security feature is configured by the ip inspect inspection-name {in  out} command？（）