Where Does Start-up Time Come From?

I’m curious how start-up operating system time and date is set. I’ve seen some BBB’s reboot to November 2013 and some reboot to January 2013. How is that date determined? Is it built into the kernel as a static value somewhere or perhaps into u-boot?

Thank you,

It's built into the init scripts. These boards lack a battery backed
real-time clock, so usually we pre-seed the date with a timestamp from
the day we built the image. As long as you have internet access, the
date should be updated by ntp fairly quickly, so most users won't
notice this. For those that notice, it's still better then having a
default date of 1970.