We have a simple app that we created in our enterprise environment for internal use. The primary PCs that will be accessing the app are restricted from accessing resources outside of our network. I didn't realize the impact of that on the Esri Basemap information in the application and also the search functions.
I'm assuming the only option would be to open port 80 on the computers?
If there's another way or that assumption is incorrect I trust that the community here will confirm :)
You might want to whitelist a few domains. Also enable TLS 1.2 or later, if not already done.
Here is nice document that lists out the required domains. Domain Requirements for ArcGIS Online (esri.com)
The old school way was to create your own cache and search services. Probably not really practical now. Do you have a forward proxy that can be used? You could use a proxy.ashx approach:
So that you can trust your web server (where the JSAPI app is installed), to speak to the internet on the ports mentioned above. That way you consolidate all requests to a known point and create a trust out from there. This can help get things through security, but depends on the reasons why your so locked down in the first place.