Ever wondered what the meaning is of the registry entries which you can find under HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Virtual Machine\Guest\Parameters? Well I did so I started digging!

Example Azure Virtual Machine

[HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Virtual Machine\Guest\Parameters]
“HostName”=”RD009CFA1C5432”
“HostingSystemEditionId”=dword:00000008
“HostingSystemOsMajor”=dword:00000006
“HostingSystemOsMinor”=dword:00000002
“HostingSystemProcessorArchitecture”=dword:00000009
“HostingSystemSpMajor”=dword:00000000
“HostingSystemSpMinor”=dword:00000000
“PhysicalHostName”=”RD009CFA1C5432”
“PhysicalHostNameFullyQualified”=”RD009CFA1C5432”
“VirtualMachineId”=”68DDDEBF-E94F-4C3C-9872-35A6BDE52F60”
“VirtualMachineName”=”04820db9-7477-4503-9eeb-df46f0969612”

HostName

The name of the domain name system (DNS) domain assigned to the host operating system. If the host operating system is a node in a cluster, then this is the DNS domain name of the cluster virtual server (not to be confused with Virtual Server).

HostingSystemEditionId

The product type. If the specified operating system is less than the current operating system, this information is mapped to the types supported by the specified operating system. If the specified operating system is greater than the highest supported operating system, this information is mapped to the types supported by the current operating system. 00000008 stands dfor Windows Server Datacenter. More info here.

HostingSystemOsMajor

The major version number of the operating system. The minimum value is 6. For example, Windows Vista and Windows Server 2008 are version 6.0.0.0, Windows 7 and Windows Server 2008 R2 are version 6.1.0.0, Windows Server 2012 is version 6.2.0.0. and Windows Server 2012 R2 is version 6.3.0.0.

HostingSystemOsMinor

The minor version number of the operating system. The minimum value is 0. This is the second number in the version number. For example, Windows Server 2012 would be a 2 and Windows Server 2012 R2 a 3.

HostingSystemProcessorArchitecture

The information regarding this registry entry is very hard to find. So here are some assumptions. It might be used for “Processor Compatibilty” when a virtual machine is part of a cluster or it’s just there to indicate the difference between Intel and AMD. If you know what the usage of this entry is please leave a comment!

HostingSystemSpMajor

The major version number of the operating system service pack. The minimum value is 0.

HostingSystemSpMinor

The minor version number of the operating system service pack. The minimum value is 0.

PhysicalHostName

The DNS host name of the host operating system. Even if the host operating system is a node in a cluster, this is the DNS host name of the host operating system, and not the name of the cluster virtual server.

PhysicalHostNameFullyQualified

The fully qualified DNS name that uniquely identifies the host operating system. Even if the host operating system is a node in a cluster, this is the fully qualified DNS name of the host operating system, not the name of the cluster virtual server. The fully qualified DNS name is a combination of the DNS host name and the DNS domain name, using the form HostName.DomainName.

VirtualMachineId

This is the unique Virtual Machine ID (SID) given to a virtual machine.

VirtualMachineName

The name of the virtual machine in which this guest operating system is running.