2949696 - XSController does not start - UnknownHostException

XSController can not be started. In xscontroller_0.log the followings can be seen:

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Failed to start controller
com.sap.xs2rt.controller.ControllerExceptions$ControllerStartUpException: Could not startup the controller components: The controller is not available via the platform router. The cause for this could be port 31930 is unavailable, wrong proxy settings, an unreachable or incorrect domain or others. Please check the SAP WebDispatcher logs in /hana/shared/<SID>/xs/controller_data/controller/router/webdispatcher/logs and the controller log.
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Caused by: com.sap.xs2rt.core.rest.client.RestException: Error executing request GET https://<hostname1>:31930/v2/info: java.net.UnknownHostException: <hostname1.domain1>
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Caused by: javax.ws.rs.ProcessingException: java.net.UnknownHostException: <hostname1.domain1>
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Caused by: java.net.UnknownHostException: <hostname1.domain1>
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SAP HANA Extended Application Services Advanced Model

XSA, XS, XS advanced, network issue, hostfile, default domain, domain , KBA , BC-XS-RT , XS Advanced Runtime / XS Controller , Problem