no debug all
Disables all active debug commands on the router to stop excessive console output and reduce CPU load, typically used after troubleshooting is complete.
no debug allWhen to Use This Command
- After finishing OSPF neighbor troubleshooting to stop debug ip ospf events output.
- When a router becomes unresponsive due to high CPU from multiple debug commands.
- Before leaving a production router to ensure no debug commands remain active.
- When a junior engineer accidentally enables debug all and needs to quickly disable all debugging.
Command Examples
Disabling all active debugs
no debug allAll possible debugging has been turned off
The single line confirms that every active debug command on the router has been disabled. No further output is generated.
Verifying debugs are off after disabling
show debugNo active debug commands
After issuing 'no debug all', the 'show debug' command confirms that no debug commands are currently active.
Understanding the Output
The output of 'no debug all' is a single confirmation line: 'All possible debugging has been turned off'. This indicates that every debug command that was previously enabled (e.g., debug ip ospf events, debug ip packet) has been disabled. In a real network scenario, you would use this command to stop the flood of debug messages that can overwhelm the console and degrade router performance. After running it, you should verify with 'show debug' that no active debugs remain. If the router was experiencing high CPU due to debugging, you should see CPU utilization drop in 'show processes cpu'.
CCNA Exam Tips
CCNA exam tip: 'no debug all' is the safest way to disable all debugging; 'undebug all' is an alias and works identically.
CCNA exam tip: Remember that 'debug all' can crash a router; always use 'no debug all' to turn it off.
CCNA exam tip: The exam may test that 'no debug all' is a privileged EXEC command, not available in user EXEC mode.
CCNA exam tip: After troubleshooting, always disable debugs to avoid performance issues; the exam expects you to know this best practice.
Common Mistakes
Mistake 1: Using 'no debug all' in user EXEC mode — it fails because it requires privileged EXEC mode.
Mistake 2: Forgetting to disable debugs after troubleshooting, causing high CPU and potential router crash.
Mistake 3: Typing 'no debug all' but not realizing it only affects the current session; debugs enabled in other VTY lines remain active.
Related Commands
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