单项选择题 A project requires a new server to be set up with the ability to automatically fail over its Ethernet connection to a second connection if a network failure occurs. Which of the following provides greatest resiliency？（）

单项选择题 After updating serverB’s network configurations， an administrator notices that serverA， which resides in a different subnet， is unable to communicate with serverB via ssh or telnet. As ping’s to the server fail， the administrator logs onto serverB via a console and finds an available interface en0 in the ‘up’ state.From the console connection， en0 can communicate with other servers in the same subnet. What is the most likely cause of the problem？（）

单项选择题 Whichofthefollowingcananoperatorusetoshutdownasystemintosingle-usermode？（）