In case you need overview of the Differences between L1, L2, L3 system administrator and exactly what are duties of the Level I: Novice System Administrator, Level II: Junior System Administrator, Level III: Intermediate/Advanced System Administrator, Level IV: Senior System Administrator and Management-level job descriptions I have bumped into a nice document which describes Required Skills, Required Background, Desirable Background and Skills and Appropriate Responsibilities for each role. Check it out at https://www.usenix.org/system/files/lisa/books/usenix_22_jobs3rd_core.pdf