When I boot my Macbook Pro while holding the F1 button a globe shows up and after a while the computer resumes to boot just as if nothing happened.
What does this button trigger?
It seems like an easy enough question to put into google, yet the only thing I found was this.
Unfortunately the question left unanswered.
Holding F1 during boot tells the computer to look for a special startup disk located on the network (using NetBoot on Mac OS X Server), just like how C looks for a startup volume on the CD/DVD inserted or N looks for a normal Mac OS X NetBoot image Option opens up the interface to choose your startup disk.
F1 looks for the EFI Hardware Diagnostic startup available on the network: It’s primarily designed for running Xserve Diganostics (See More: Apple). As far as I know only the Xserve’s diagnostics are able to be netbooted.
You can find more about NetBoot on Wikipedia.
I read some where that:
You can also set the default as
Network Boot Volumes by holding F1
(Intel Macs). A ‘globe icon’ will
appear on the screen while it is
searching for a server.
and if no network find:
Holding down F1 during boot (after
chime) makes a planet appear, which
blinks three times. Then it continues
booting as usual.