Your ESXi hosts can use a vSphere Authentication proxy if they have the Authentication Proxy certificate information.
You need only authenticate the server once.
Note: ESXi and the Authentication Proxy server must be able to authenticate. Make sure that this authentication functionality is enabled at all times. If you must disable authentication, you can use the Advanced Settings dialog box to set the UserVars.ActiveDirectoryVerifyCAMCertifcate attribute to 0.