Does an SEP 12.1 client pull def updates when it starts?

I've always assumed that if a workstation has been shut down, that when it's restarted, it will query the SEP managmement server for A/V definition updates.  Is this true?  What if the LU policy says that the Retry Windows is X hours and it's been more than that since the workstation was turned off? 

I'm just trying to understand how the SEP agent behaves.

Thanks!
Mark