单项选择题 While attempting to expand a file system, an administrator receives an error message indicating that the filesystem is not recognized. Running the lsfs command fails to display any output, but the df command is working and displays normal filesystems. What is the likely cause of the problem?（）

单项选择题 The server host1 has been set up as a backup system with the following /etc/exports./backups -rw. How can a second server regularly use this disk space?（）

单项选择题 Which communication protocols are valid between the NIM master and standalone clients?（）