ESXi hosts can be configured to join a Microsoft Active Directory domain, which enables a user to access the host with the same credentials as his Active Directory domain credentials. If Active Directory is in sync with the vSphere environment, then every time a user is prompted to enter the credentials, Active Directory credentials can be used for authentication purposes, eliminating the need of creating host based local accounts.

This service is very useful in managing large server architectures, and all the user accounts can be centrally managed by Active Directory. This architecture provides more security and also ease to manage accounts independently from the hosts. However, local users can still be created and configured as per requirements using the vSphere Web Client. Root user can not be created or synced with an Active Directory account and needs to be separate at all times.

Using Active Directory for managing user accounts also...