To restart an unresponsive Citrix ADC MPX appliance and capture a core dump, which action should the administrator take?

• A. Turn off the appliance using the power button.
• B. Use the reset button on the front of the appliance.
• C. Use a USB port to issue a restart command.
• D. Use the NMI button on the back of the appliance.

Answer: (D)

When an unresponsive Citrix ADC MPX appliance needs debugging, you want a method that guarantees a diagnostic memory dump is created before the system restarts. The Non-Maskable Interrupt button on the back is designed for this scenario. Pressing it forces the system to generate a crash dump (core dump) and then reboots, making the dump available for analysis by support or engineering. This approach is specifically meant for capturing diagnostic data from a hung state.

Other options don’t reliably produce a core dump or can cause data loss. Powering off abruptly may corrupt files and won’t guarantee a dump; a front-panel reset can simply reboot without capturing the necessary memory state; and a USB restart command typically requires the OS to respond, which isn’t possible when the device is unresponsive. The NMI button directly triggers the crash dump process, providing the needed diagnostic data to understand and resolve the issue.