Which of the following is a way to protect server operating systems from a short term contractor？（）

A. Policies and procedures
B. Encryption
C. Locked doors
D. Security personnel
E. Backup tapes

A. Online troubleshooting tools
B. Service Level Agreement （SLA）
C. Vendor website
D. Support forums

A. Survey users to get their response to the potential server change.
B. The change should be approved by management.
C. Switch over to the alternate site so users are not affected.
D. Implement RAID so the server does not go offline.