How can you add debug logic to APM iRules for troubleshooting purposes?

Question

Options

• ABy enabling verbose logging in the APM configuration settings
• BBy using the "log" command within the iRule to log specific events
• CBy running the "debug" command from the BIG-IP command-line interface (CLI)
• DBy importing third-party debug modules into the iRule

• A
  4% (1)
• B
  82% (23)
• C
  11% (3)
• D
  4% (1)

Explanation

Using the log command within an iRule is the correct approach because iRules are event-driven scripts that execute on the BIG-IP data plane, and the built-in log command lets you write custom messages (variable values, event names, client IPs, etc.) to /var/log/ltm or a remote syslog server at specific points in the rule's execution.

Why the distractors are wrong:

• A - APM's "verbose logging" setting controls session-level audit logs, not iRule execution flow; it can't insert logic at specific iRule events.
• C - There is no debug CLI command that attaches to live iRule execution; CLI tools like tmsh manage configuration, not runtime script tracing.
• D - iRules use Tcl and do not support importing external modules or packages of any kind; the runtime environment is sandboxed.

Memory tip: Think of iRules like shell scripts - when you want to troubleshoot a shell script, you add echo statements. In iRules, log is your echo. The pattern is log local0. "my message", where local0 is the syslog facility.

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