VMware 6.7 host could not be added as a protected asset, receiving error "the name vCenter-RRC could not be resolved on the network"

SUMMARY

Steps to resolve an issue where a VMware 6.7 host or vCenter instance was attempted to be added prior to updating to v10.3 and failed, but not resolved by updating the appliance, receiving the message "the name vCenter-RRC could not be resolved on the network"

ISSUE

A VMware host or vCenter instance fails to add to the appliance as a protected asset, the error received is "the name vCenter-RRC could not be resolved on the network"

RESOLUTION

To resolve this issue take the following steps:

1. Confirm the appliance's software version is 10.3 or higher, this can be done by navigating to Configure > Appliances and looking at the VERSION column.  If the appliance is not on version 10.3 it must be upgraded before a VMware 6.7 host or vCenter can be protected, for steps to update the appliance please see KB 4218, and if you do not see version 10.3+ as an available version to update please see KB 6303
2. Open the command line of the appliance using a SSH console emulator such as PuTTY and login as "root" to confirm that your appliance can reach the host or vCenter through port 443 by entering the following command, replacing the IP address as listed in red below with your host or vCenter's IP address:

   [root@Unitrends ~]# nmap 192.168.1.5
   
   Starting Nmap 5.51 ( http://nmap.org ) at 2018-11-26 14:19 EST
   Nmap scan report for vcenter.mydomain.local (192.168.1.5)
   Host is up (0.00029s latency).
   Not shown: 987 filtered ports
   PORT STATE SERVICE
   22/tcp open ssh
   80/tcp open http
   443/tcp open https
   
   MAC Address: 00:00:00:00:00:00 (VMware)
   
   Nmap done: 1 IP address (1 host up) scanned in 4.80 seconds
   [root@Unitrends ~]#

   In the example above port 443 is shown as open.  If you see port 443 listed as anything other than "open," for example "closed" or "filtered," please ensure that all of the ports needed by the Unitrends appliance are open and available as described in KB 1151
3. Continuing in the command line confirm that we can retrieve the correct FQDN of the host or vCenter instance:

   [root@Unitrends ~]# nslookup
   > 192.168.1.5
   Server:         192.168.1.2
   Address:        192.168.1.2#53
   
   13.3.159.10.in-addr.arpa        name = vcenter.mydomain.local.
   > exit
   
   [root@Unitrends ~]#

   If you do not return the correct FQDN please check to make sure the correct DNS server is listed in the result (indicated by "Server") and if not you can navigate to Configure > Appliances > Network, select the appropriate adapter and click Edit, then enter the correct DNS IP address.  After performing that step you should be able to find the correct FQDN with the above command, if not additional remediation may need to be done in your DNS server.
4. Navigate in the Unitrends web GUI to Configure > Appliances > Network > Edit Hosts File, then find the entry for localhost (127.0.0.1) select it and click Edit.  Under "Aliases" enter "vCenter-RRC" without the quotes, if another alias already exists it must be proceeded by a comma "," to separate it from prior entries.  Click Save and then Close the "Edit Hosts File" dialog.
5. Navigate to Configure > Protected Assets and attempt to add the host or vCenter to the appliance.