[单项选择题]A server has five hot pluggable SCSI disk drives in a RAID 5 array. The server OS crashed and the server will not boot. The administrator noticed that all of the disk drives have gone offline. Which of the following components would MOST likely have caused the problem？（）

[单项选择题]Which of the following is the MOST effective method to restrict staff members from accessing a service on a company server？（）

[单项选择题]There is a power outage and all servers are shut down properly by the uninterruptible power supply（UPS） software. When one of the servers starts up it displays a logical drive failed error. This server has two processors，16GB of memory， and a RAID 5 array with 10 drives. Which of the following is the MOST likely cause？（）

[单项选择题]When load balancing traffic between two web servers， which of the following technologies provides the LOWEST cost solution？（）