Lost Web Shortcuts in Dock on Restart

I created web shortcuts for various cloud based programs in my dock and gave them pictorial icons. When I restarted the Mac they all turned to question marks. Can I restore them? Or if I do them over can I stop this from happening on next restart?
Thanks

You probably only created temporary aliases of the web sites. And yes, they will disappear upon a reboot. This article from Apple explains how to permanently place them on the dock so they remain like other dock icons.