Nintex Workflow Call Web Service Issue “Cannot Resolve Server Name”

I recently ran into the following message when trying to configure the Call Web Service action in Nintex Workflow 2013: “Cannot resolve server name” (see image below). No matter what I tried, I received that error message every time we hit the Refresh button beside the Web method setting.

This issue was due to the Web Front End server not being able to resolve the URL of the web application from the server itself. As many of our sites are public facing, the majority of DNS is handled by external DNS servers, and all URLs are not by default added to internal DNS. This is fine the majority of the time, but there are instances, and this was one, where the server itself needed to resolve the name.

I solved this issue by adding the URL to the Web Front End’s hosts file (we’ll call that “manual DNS”) and verified that we could access the site afterwards from the server itself (which we could). This caused the problem to be fixed within the Nintex UI.