Which Run Levels Should Never Be Declared as the Default Run Level When Using SysV Init? (Choose TWO Correct Answers.)
Question
Which run levels should never be declared as the default run level when using SysV init? (Choose TWO correct answers.)
Answers
Explanations
Click on the arrows to vote for the correct answer
A. B. C. D. E.AE
In SysV init, run levels define the state in which the system is running. Different run levels have different sets of services running on the system. The default run level is the run level that the system boots into by default.
The run levels that should never be declared as the default run level when using SysV init are 0 and 6. Here's why:
Run level 0 (also known as "halt" or "shutdown") is used to shut down the system. If this is set as the default run level, the system will always shut down when it boots up. This is obviously not desirable, as you won't be able to use the system at all.
Run level 6 (also known as "reboot") is used to reboot the system. If this is set as the default run level, the system will always reboot when it boots up. This is also not desirable, as you won't be able to use the system at all.
On the other hand, run levels 1, 3, and 5 are perfectly valid choices for default run level. Here's why:
Run level 1 (also known as "single user mode") is used for system maintenance tasks, such as resetting passwords or fixing system issues. Setting this as the default run level would mean that the system always boots into single user mode, which can be useful if you need to perform system maintenance frequently.
Run level 3 (also known as "multi-user mode with networking") is the standard operating mode for most Linux systems. In this mode, most services are running and the system is fully functional. Setting this as the default run level would mean that the system boots into a fully functional state, which is what most users want.
Run level 5 (also known as "multi-user mode with networking and GUI") is the same as run level 3, but with the addition of a graphical user interface (GUI). Setting this as the default run level would mean that the system boots into a fully functional state with a GUI, which is what most desktop users want.
So, in summary, run levels 0 and 6 should never be declared as the default run level when using SysV init, while run levels 1, 3, and 5 are perfectly valid choices.
