Hi Vinay KN,
You are fully compliant with your current licensing setup and do not require any additional purchases to join your physical Hyper-V hosts to the domain. The Windows Server 2019 Standard licensing model grants you rights to two virtual operating system environments alongside the physical host, provided that the physical operating system is utilized strictly for the Hyper-V role and associated management tasks. Authenticating physical servers against an Active Directory domain is classified natively as a standard management function, meaning you can join servers two through six while keeping your infrastructure completely within Microsoft compliance boundaries.
You can also confidently join your first server to the domain despite the primary domain controller running as a guest virtual machine on that exact hardware. During a host reboot when the domain controller is temporarily offline, the operating system simply relies on secure cached credentials located in the HKEY_LOCAL_MACHINE\Software\Microsoft\Windows NT\CurrentVersion\Winlogon registry hive to process your administrative login. To guarantee seamless operation, you must configure the domain controller virtual machine to power on with the physical server by setting the Automatic Start Action within the Hyper-V virtual machine settings to always start automatically. This ensures the Active Directory services initialize immediately to authenticate the host and service the broader network.
Hope this answer brought you some useful information. If it did, please hit “accept answer”. Should you have any questions, feel free to leave a comment.
VPHAN