This is some times common you document something and if don't implement or use something since long you might forget knowledge or the issues you resolved earlier. I was automating join domain ESXi servers, while trying joining I was keep getting error: Errors in Active Directory Operations. I already had written article for the same. POWERCLI AND VSPHERE WEB CLIENT: JOIN ESXI INTO ACTIVE DIRECTORY DOMAIN CONTROLLER, here I have mentioned to check few ports. But everything was working. but still getting below error.

After going through my earlier article, As per above screenshot I was using correct credentials, but wrong way. You must not use DomainName\UserName while providing credentials. Instead you must use it as [email protected], As shown it will be successful immediately.

Next if you are using Powercli to deploy this task and using user name same way DomainName\UserName in the credentials, It will throw same error. 

cmdlet Get-Credential at command pipeline position 1
Supply values for the following parameters:
Credential
Set-VMHostAuthentication : 11/25/2017 8:53:36 PM        Set-VMHostAuthentication                The operation for the entity "esxi001.vcloud-lab.com" failed with the following message: "Errors in Active Directory operations."
At line:1 char:59
+ ... d-lab.com | Set-VMHostAuthentication -Domain vcloud-lab.com -Credenti ...
+                 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    + CategoryInfo          : NotSpecified: (:) [Set-VMHostAuthentication], ActiveDirectoryFault
    + FullyQualifiedErrorId : Client20_TaskServiceImpl_CheckServerSideTaskUpdates_OperationFailed,VMware.VimAutomation.ViCore.Cmdlets.Commands.Host.SetVMHostAuthentication

In the second example I used username in email form [email protected] in the credential pop up box. and it was successful.

Useful Blogs
POWERCLI AND VSPHERE WEB CLIENT: JOIN ESXI INTO ACTIVE DIRECTORY DOMAIN CONTROLLER
How to configure DNS on esxi server
VMWARE SECURITY BEST PRACTICES: POWERCLI ENABLE OR DISABLE ESXI SSH
Reset forgotten ESXi root password on Domain joined Esxi using vSphere web client and Powercli