Sync 1 xls file between computer and network drive

[olds]

Same file in two places.
When you work in the file on the computer, the file on the network drive gets updated automatically.

Seems like I did this years ago but my brain is failing me...
How do I do this?
TIA

EDIT
I did it with the Briefcase but that's not how I recall doing it.

 

[yinan]

Offline files can do this.

 

[Gooberlx2]

Robocopy can run as a process and monitor folder (not file) changes.

link

Something like:

robocopy /copyall /zb /mon:1 c:\source\ d:\dest\

This will update the folder contents every minute if changes have been made.

You could probably put this in the startup folder, or schedule a task at reboot, or add it to one of the registry areas. The issue is it will run in a command prompt window, which is annoying. Maybe creating a custom service could prevent that...I don't know.