You should know how to use the mksysb command to create a backup image of the system and how to restore from it.
You can use the AIX System Management Interface Tool (SMIT) utilities to install software and configure devices. If you haven't used SMIT before, look through the IBM IBM Knowledge Center.
You need some understanding of how AIX handles device definitions, how it structures file systems and directories, and how it uses processes and page space. All this information is available in System User's Guide; Operating System and Devices.
You also need to know how to use a text editor to edit files.