During a penetration test, you discovered that an organization's server room is protected by a single door requiring a proximity card for entry. During your assessment, you noted several instances where unauthorized personnel could follow authorized personnel through the door without presenting a proximity card (tailgating). Which recommendation would best enhance physical security to mitigate this issue in the future?
Set up a man trap with biometric security features at the server room entrance.
Increase the frequency of security guard patrols in the area of the server room door.
Issue additional proximity cards to all personnel to ensure everyone has their own means of access.
Install an access control vestibule that requires authentication before entry to the secure area.