Container for the parameters to the ModifyHosts operation. Modify the auto-placement setting of a Dedicated Host. When auto-placement is enabled, AWS will place instances that you launch with a tenancy of host, but without targeting a specific host ID, onto any available Dedicated Host in your account which has auto-placement enabled. When auto-placement is disabled, you need to provide a host ID if you want the instance to launch onto a specific host. If no host ID is provided, the instance will be launched onto a suitable host which has auto-placement enabled.