Which three are needed to run VRF lite for IPv6 on a router？ （）

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

What is the STP root guard feature designed to prevent？（）

IEEE 802.1w is a Rapid Spanning Tree Protocol （RSTP） that can be seen as an evolution of the 802.1 standard. What are the port roles described by 802.1w？（）

You are the network administrator of a Layer 3 switched network. Users in one VLAN are complaining that access to the server VLAN is very slow from time to time. Traffic in the local VLAN works without any issue， and users in other VLANs do not have any complaint to reach the server VLAN. What is most likely the cause of this issue？（）

When a BGP router is not capable of understanding 4-byte AS numbers， it will see 4-byte AS numbers as a special， reserved， 2-byte AS number in the AS path. Which 2-byte AS number is this reserved one？（）

Which three statements are true about policing？ （）

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？（）

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

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