After removing the virus from the server, the administrator should perform the following actions to mitigate the issue from reoccurring and to maintain high availability:
* Run a vulnerability scanner on the server to identify any other potential weaknesses or exposures that could be exploited by attackers.
* Patch the vulnerability that allowed the virus to infect the server in the first place, using the latest updates from the database software vendor or a trusted source.
* Update the antivirus software on the server to ensure it has the most recent virus definitions and can detect and prevent future infections. The other options are either unnecessary or counterproductive for this scenario. Repartitioning the hard drive, reformatting the OS, removing the database software, or air gapping the server from the network would cause downtime and data loss, while enabling a host firewall would not prevent a virus infection from within the network. References: CompTIA Server+ Certification Exam Objectives, Domain 5.0: Security, Objective 5.2: Given a scenario involving a security threat/vulnerability/risk, implement appropriate mitigation techniques.