Option D is the best answer because the server is still operational , cannot be shut down , and may contain volatile evidence that could disappear quickly. Under CHFI principles, when a system must remain running and critical data in memory or live state may be lost, the investigator should perform a live acquisition while respecting the order of volatility .
This is exactly the kind of situation where live acquisition is required. It allows the examiner to collect RAM contents, active processes, network connections, logged-in sessions, open files, and other transient artifacts that would be lost if the system were powered down or delayed. Since the question explicitly highlights volatility, immediate live acquisition is the most appropriate forensic response.
Option A is not a substitute for forensic acquisition because ordinary backups do not necessarily preserve volatile evidence or forensic integrity in the same way. Option B delays the response and risks losing critical data. Option C may provide useful supporting network information, but it does not capture the server's internal volatile state. Therefore, the correct CHFI-aligned next step is to conduct a live acquisition immediately .