A system electronic log is the most useful source of information for an IS auditor to review all access attempts to a video-monitored and proximity card-controlled communications room. A system electronic log can provide accurate and detailed records of the date, time, card number, and status (success or failure) of each access attempt. A system electronic log can also be easily searched, filtered, and analyzed by the auditor to identify any unauthorized or suspicious access attempts.

A manual sign-in and sign-out log is not as reliable or useful as a system electronic log, because it depends on the honesty and compliance of the users. A manual log can be easily manipulated, forged, or omitted by the users or intruders. A manual log also does not capture the status of each access attempt, and it can be difficult to verify the identity of the users based on their signatures.

An alarm system with CCTV is not as useful as a system electronic log, because it only captures the events that trigger the alarm, such as unauthorized or forced entry. An alarm system with CCTV does not provide a complete record of all access attempts, and it can be affected by factors such as camera angle, lighting, and resolution. An alarm system with CCTV also requires more time and effort to review the video footage by the auditor.

A security incident log is not as useful as a system electronic log, because it only records the incidents that are reported by the users or detected by the security staff. A security incident log does not provide a comprehensive record of all access attempts, and it can be incomplete or inaccurate depending on the reporting and detection mechanisms. A security incident log also does not capture the details of each access attempt, such as the card number and status.