I have a web site hosted in an EC2 instance (2008 r2 + iis7.5 + sql server). I put one linux box running RHEL with varnish. After some configuration trail and error, I found a configuration that works.

Now I want to duplicate the varnish boxes to other availability zones, but continue to pull the pages from the original windows box.

It is my understanding that I can put the varnish boxes in different zones and pull from the windows box via it's external IP. But what do I need to do in order for each user to receive content from the box physically closest to them? Is this even possible?

Thank you!