Cisco Systems CCNA 2 manual Introduction to debug

the troubleshooting process. Students need to realize that there is a lot of output that will be completely unfamiliar to them. The two main reasons for them to use this command are to discover the cable type connected to the serial interface and to see the clock rate on the interface with the DCE cable.

9.3.7 Introduction to debug

The debug command is used to display dynamic data and events. The debug command output gives more insight into the current events of the router. The dynamic output of the debug command has a high performance cost. It produces a high processor overhead that disrupts normal router operation. Debug should be used conservatively. Stress to the students that debug is a very important tool. However, this command can disrupt router operations and cause network performance to decrease drastically. It should only be used to diagnose a problem and then it should be turned off.

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