Add an alias for the system in /etc/hosts file on the logcollector i.e. prefix or suffix a unique string to the hostname portion of the fqdn. eg. NW-Test.DELL.CORP.EMC.IN (added NW- as a prefix to hostname portion of fqdn)
Run below setspn command on Windows Server. This will add a new unique spn to Active directory and map it to the hostname. setspn -A HTTP/NW-Test.DELL.CORP.EMC.IN Test
On Netwitness W UI, add the event source to the collector using the new alias as the hostname i.e. NW-Test.DELL.CORP.EMC.IN and test connection to get success.