QA

Q&A

The questions and scenarios in this book are more difficult than what you should experience on the actual exam. The questions do not attempt to cover more breadth or depth than the exam; however, they are designed to make sure that you know the answers. Rather than allowing you to derive the answers from clues hidden inside the questions themselves, the questions challenge your understanding and recall of the subject. Hopefully, these questions will help limit the number of exam questions on which you narrow your choices to two options and then guess.

The answers to these questions can be found in Appendix A.

1.	Why would a unidirectional link be bad?
2.	What condition must be met to keep a switch port in the Blocking state?
3.	If a switch port is shown to be in the root-inconsistent state, what has happened on it?
4.	When root guard has been triggered on a switch port, what must be done to enable the port for use again?
5.	When BPDU guard is enabled on a switch port, what state will the port be put in if a BPDU is received on it?
6.	When BPDU guard has been triggered on a switch port, what must be done to enable the port for use again?
7.	When loop guard is enabled on a switch port, what state will the port be put in if BPDUs are noted to be missing?
8.	Can STP loop guard be enabled on all switch ports?
9.	When UDLD is enabled on a switch port, what else must be done to detect a unidirectional link on the port?
10.	What is the difference between the UDLD normal and aggressive modes?
11.	What command enables UDLD aggressive mode on a switch interface?
12.	If two switches enable UDLD on the ports that have a common link, do their UDLD message times have to agree?
13.	UDLD should be used on switch ports with what type of media?
14.	Can UDLD be used on all switch ports without causing problems?
15.	Is it possible to disable STP on a single switch port without disabling the whole STP instance? If so, how can you do that?
16.	Complete the following command to display all ports that are disabled because of STP protection features: show spanning-tree ______________