Thanks Josh.. I got it figured out. it was due to the role of the admin account on ESXi which was missing. hence those accounts could not be used to add ESXi hosts to VxRail. I updated the roles in ESXi host using the esxcli system permission set command. btw the accounts need "Admin" role on ESXi, which was present on other ESXi hosts but for some reason was missing on the problematic ESXi hosts. Once the permissions were updated and management password updated, it worked like a charm  
Hi Guys,I am having difficulty updating the management password for a couple of ESXi hosts in VxRail Appliance. and these are appliances are reporting "This host is missing. The following data is from cached information and may no longer be accurate. " from health Monitoring page.Followed the below article in updating the password, however once the curl command is run, the status shows OK for few Minutes before becoming INVALID again. -- Dell Article 61400 I have tried restarting the PTAs and verified the communication is OK. even rebooted the host. --Dell Article 52348
updating the management password for a couple of ESXi hosts in VxRail Appliance