The administrator should perform an antivirus scan on all servers within the cluster and reboot each server, and block access to 208.206.12.9 from all servers on the network. These actions will help to remove any malware that may have infected the application server and prevent any further unauthorized traffic to the known-bad public IP address. An antivirus scan can detect and remove malicious software that may be sending data to an external source, and a reboot can clear any temporary files or processes that may be related to the malware. Blocking access to 208.206.12.9 from all servers on the network can prevent any future attempts to communicate with the malicious IP address.

User activity reports were used to identify the security breach in the human resources department. User activity reports are records of the actions and events performed by users on a system or network, such as login/logout times, files accessed or modified, commands executed, or websites visited. User activity reports can help monitor and audit user behavior, detect and investigate security incidents, and enforce policies and compliance. User activity reports can be generated by various tools, such as log management software, security information and event management (SIEM) systems, or user and entity behavior analytics (UEBA) solutions. Reference: [CompTIA Server+ Certification Exam Objectives], Domain 5.0: Security, Objective 5.2: Given a scenario, apply logical access control methods.

Explanation
The loud noises from the servers are most likely caused by failing hard disk drives, which can produce clicking or grinding sounds. Replacing the drives with new ones can prevent data loss and downtime.
Replacing the drives can be done without shutting down the server if they are hot-swappable, which means they can be removed and inserted while the server is running. References: CompTIA Server+ Certification Exam Objectives, Domain 3.0: Storage, Objective 3.1: Given a scenario, install, deploy, configure and update physical storage devices.

Explanation
Secure Sockets Layer (SSL): SSL and its successor Transport Layer Security (TLS) enable client and server computers to establish a secure connection session and manage encryption and decryption activities.