Are you seeking a career in Linux system administration? If yes, then you need to be thorough with the basic knowledge of Linux and should be confident enough to answer Linux based questions. To help you out, we have selected the top 20 questions for Linux system administration and presented in four parts -- each section dealing with 5 questions. The first section deals with the basic level questions that anyone who has completed Red Hat Certification course will be able to answer, but it's ow you present it matters the most. Q1. Define Linux and give the reason behind its popularity An operating system based on UNIX and Linux Kernel and was first introduced by Linus Torvalds. This can be run on various hardware podium which are manufactured by IBM, HP, Intel, MIPS, SPARC and Motorola. A penguin figure called Tux is the mascot of Linux. Linux is popular because of being A free and open source Huge amount of libraries and utilities Very sturdy and adaptable. Q2. How are Linux and UNIX different from each other? Linux is a free and intended to be a non-propriety operating system for general people whereas UNIX is a propriety operating system originally from Bell Laboratories and can only be used under the copy right of UNIX. Q3. Define LILO Being a boot loader for Linux it is used to load Linux system into the memory to start the operation. Q4. Name the core of Linux. Kernel is the core of Linux which can be further broken into: Shell—a command line interpreter Command –user instruction to computer Script –collection of commands saved in a file Terminal- a command line interface. Q5. Distinguish between Bash and DOS. They are different in three areas. BASH commands are case sensitive but DOS are not BASH follows no convention in naming files but DOS follows, 8 character file name followed by a dot along with 3 character for extension. Under BASH, /is a directory separator and is an escape character whereas for DOS / is an argument delimiter command and a directory separator. In the following segments you will find the other questions frequently asked during the Linux system administration interview.