LDAP User authrntication failed on 3rd party application (or) DCdiag failed return value = 81 (or) Naming information cannot be located.

Error's:
LDAP User authentication failed on 3rd party application connecting to AD for authentication.
DCdiag CMD failed.
Naming information cannot be located


Issue:
Customer reported Unable to login to tools applications console's.


Resolution:

First check the replication status, using below cmd
CMD>> repadmin /showrepl * /csv >showrepl.csv
run the above cmd on any domain controller, it will generate a report, check if you have any replication error and when the last sync was happened in the report.
if some error reported, then note the destination & source DC name.
then go to the domain controller rdp, run the below cmd in Command line.
CMD >> dcdiag
if you get below error message, then there is authentication issue on that domain controller.
fix: reboot the DC and re-run "dcdiag" CMD, if it is succussfull, then issue is resolved.
in our case, it was because some patch installed in the DC, which caused the services hanging.


Error:
Performing initial setup:
   Trying to find home server...
   Home Server = XXXXXXXXX
   Ldap search capability attribute search failed on server XXXXXXXXX,
   return value = 81