ZTNA RDP Application failing using FQDN

Products

• Symantec ZTNA

Issue/Introduction

ZTNA admin created an RDP application referencing an internal IP address, and users could RDP successfully to that host after authenticating to the ZTNA Portal.

ZTNA Admin added a second RDP application, but a DNS name was used instead of using an internal IP address. 

Users could not access this RDP application without getting connectivity errors.

The ZTNA Application page showed the following connectivity warning for the DNS referenced RDP APplication.

The same error is visible for Web or SSH applications referencing a DNS name.

ZTNA configured DNS servers are accessible from the connector.

 

Environment

ZTNA connector installed on Linux host.

Host running connector pointed to DNS 8.8.8.8 to download initially connector, but then changed to point to internal DNS server after that.

Cause

The initial ZTNA connector host setting had public DNS settings (8.8.8.8) in order to download container successfully. These DNS setting were copied to the actual docker container when installed.

After DNS settings were changed on the ZTNA connector to use local DNS servers, those settings were not copied to docker image and docker continued to use public DNS server. 

Resolution

Make sure you restart docker container after changing DNS setting on ZTNA using:

docker stop <docker name>
docker start <docker name>

The docker restart is needed as admin did not have permissions to manually change the DNS settings within docket container.