Explain how rescue media is used to boot a system.

What will be an ideal response?

If the system does not boot at all (e.g., due to a misconfigured /etc/fstab file or a damaged boot manager), rescue media (CDs, DVDs or USB keys) can be used to recover the system. Normally, these media boot a Linux system which you can log into as the root user without specifying a password. You should then be able to mount the file systems and have write access to all files to correct the configuration errors.