Unable to Invoke Web API

Question

I am trying to invoke an Appian web-Api using Insomnia, which is a GET method, it queries db and fetches results.
I am passing the Api key as header in insomnia.
I have mapped the service accounts and security every thing correctly, but still i am nit able to invoke the API.
I am getting this error : Error: Couldn't resolve host name

Shubham Aware · Answer

Hostname in your API URL is not reachable or not resolving. Check the exact API URL in Insomnia for typos, ensure your network/DNS can resolve that hostname, and verify no firewall or VPN is blocking access.

Harsha Sharma · Answer

Few things to check and try: 
 
 Test API outside Appian if API works as expected - this confirms your configuration like URL, service account details etc are correct 
 Once configuration is working as expected outside Appian but not in Appian then check network/ infrastructure settings for permissions.