Since vSphere 4.1 VMware has enabled Active Directory integration for ESXi into the GUI. This is a nice feature to elevate your security and make sure that your AD can be used for authentication on the ESXi host.
As with all computer account your need to be sure that the following is correct :
* DNS is configured properly on the ESXi host and can resolve AD
* ESXi host has a FQDN name and can be resolved by DNS (also correct reverse DNS lookup!)
* Time in sync with AD server for Kerberos
You can configure the directory services in the GUI by accessing the Host Configuration –> Authentication Services and then clicking the Properties. A configuration box will pop up and it will ask you for the properties for your Active Directory service.
Note ! If you want your ESXi host to be put into a specific directory in your Active Directory you’ll need to put the OU directory structure after the domain name. In my case devtest.local/Servers/ESXi in which the ESXi hosts reside in directory ou=Servers,ou=ESXi.
Next you will be asked for domain credentials (please use email@example.com) with privilege to join computer account to the domain.The right credentials will add your ESXi host to Active Directory.