Refer to the exhibit. What does the command channel-group 1 mode desirable do？ （） 

Refer to the exhibit. All network links are FastEthernet. Although there is complete connectivity throughout the network， Front Line users have been complaining that they experience slower network performance when accessing the server farm than the Reception office experiences. Based on the exhibit， which two statements are true？（）

Refer to the exhibit. Based on the output of the show spanning-tree command， which statement is true？ （）

What will occur when a nonedge switch port that is configured for Rapid Spanning Tree does not receive a BPDU from its neighbor for three consecutive hello time intervals？（）

Which statement is correct about RSTP port roles？（）

Refer to the exhibit. Initially， LinkA is connected and forwarding traffic. A new LinkB is then attached between SwitchA and HubA. Which two statements are true about the possible result of attaching the second link？（）

Which two statements are true about BPDU port-guard and BPDU filtering？（）

What two things will occur when an edge port receives a BPDU？（）

Which router redundancy protocol cannot be configured for interface tracking？（）

How are STP timers and state transitions affected when a topology change occurs in an STP environment？（）