After the initial restart, a menu with different boot options will be displayed, as shown in the following screenshot:
If no button is pressed within 5 seconds, the option used on the previous boot is automatically chosen. The different boot options are as follows:
default boot: This is the best option for most servers, and provides you with the best graphical experience.
safe video mode: This is another video configuration that may work if the default option fails. It attempts the most basic video configuration in a low resolution (1024 x 768).
kern video mode: This is another video configuration that may work if the previous options fail.
hardware safe mode: This is another option that might be better for some hardware. It disables APIC and ACPI, and hides the bootsplash screen.