Proxy configuration is required by Citrix Receiver to make the application proxy-aware. If there is no proxy configuration on Citrix Receiver, it tries to directly access the destination IP and resolve the domain from your configured internal DNS and SYN connection directly.

For proxy configuration examples, see the following Citrix documentation:

http://docs.citrix.com/en-us/receiver/windows/4-0/ica-security-wrapper-v2/ica-connect-through-proxy-server-v2.html
http://docs.citrix.com/en-us/appcontroller/2-8/xmob-appc-install-cli-web-proxy-tsk.html

Note: If Citrix changes these links, search the Citrix knowledge base for the articles instead.

For Citrix Receiver to detect the web proxy automatically based on the user’s browser configuration, select User’s browser setting.
Consult your Citrix administrator for more information.

If you have configured the User’s browser setting and see the client is unable to contact the server, refer to the following article for possible issues: TECH241075