单项选择题
When making changes to a server, which of the following is the BEST way to troubleshoot a problem?（）
A. Perform root cause analysis and then test the theory to determine the cause.
B. Make changes to the system and document everything once the problem is resolved.
C. Make multiple changes to all affected areas to resolve all potential issues.
D. Make a change and if the problem is not resolved, reverse the change.
多项选择题 Which of the following are examples of physical security measures?（）
单项选择题 A new server was installed. Most clients are located in the same subnet as the server and can successfully access the server. Clients located on different subnets have been unable to access the server, but have no trouble accessing other servers on their subnet. Which of the following is the reason that these clients are unable to access the server?（）
多项选择题 Which of the following are types of biometric devices used in server rooms?（）