We have a reverse proxy server setup (IIS + URLRewrite) that forwards external requests to an internal web application. The reverse proxy simply rewrites the external request and forwards it to the internal server which does its work -- rewrites the response and sends the response back to the client.
Problem is -- we're seeing a 5 second delay introduced on pretty much ALL requests. Without the reverse proxy -- the same request direct to the internal web application work fine (testing from internal clients).
This leads me to think this is a DNS related issue.
The lookups from the internal server must be timing out -- then the DNS server has to go out to the internet to ultimately get a response. How can I confirm this? What is the typical way to handle this issue if this is the problem?!