Netinstall can be used to

Netinstall is a MikroTik utility used to reinstall or repair RouterOS on RouterBOARD devices. It can be used to:

Reinstall RouterOS while preserving the existing license (✔B)

Install a different version of RouterOS – either older or newer (✔C)

Limitations:

A.✘Incorrect – Netinstall will erase the configuration; it cannot recover a lost admin password without wiping the device.

D.✘Incorrect – You can only install software meant for the specific hardware architecture of the RouterBOARD.

Extract from Official MTCNA Course Material – Netinstall Tool:

“Netinstall can be used to reinstall RouterOS and change its version. It does not erase the license key.”

Extract from René Meneses MTCNA Study Guide – Recovery Tools:

“Netinstall allows you to load any RouterOS version compatible with your device. It does not delete the license.”

Extract from MikroTik Wiki – Netinstall Overview:

“Netinstall reinstalls the OS, can change versions, and retains license. It cannot recover configuration or passwords.”