Final answer:
Janet should install an event management tool to automate the management of DNS server security logs. Alternatively, she could increase the maximum log size, but this is a less permanent solution.
Step-by-step explanation:
The best action for Janet, a system administrator troubleshooting an issue with a crowded DNS server security log, would be to install an event management tool. This tool can help automate the process of managing logs, providing a clearer and more scalable solution than manually deleting logs or constantly monitoring the log status. Another sound approach could be to increase the maximum log size to ensure that logs don't fill up as quickly, which would reduce the frequency of having to clear them, but this is a more temporary fix compared to utilizing an event management tool.