Computer names longer than 15 are blocked, but the limit is 63

Details of the scenario you tried and the problem that is occurring

Renaming a PC with a name that is more than 15 characters will fail. However if you rename the same PC through right-click Start, System, "Rename this PC" you can use up to 63 characters (I understand the 15 character limit comes from NetBIOS).

Verbose logs showing the problem

PowerShell DSC resource DSC_Computer failed to execute Test-TargetResource functionality with error message: Cannot validate argument on parameter 'Name'. The character length of the 16 argument is too long. Shorten the character length of the argument so it is fewer
than or equal to "15" characters, and then try the command again.
+ CategoryInfo : InvalidOperation: (:) [], CimException
+ FullyQualifiedErrorId : ProviderOperationExecutionFailure
+ PSComputerName : localhost

Suggested solution to the issue

To avoid breaking existing behaviour, add a new property that supports the 63 character limit.

The DSC configuration that is used to reproduce the issue (as detailed as possible)

Computer RenamePC
{
	Name = "1234567890123456"
}

The operating system the target node is running

OsName : Microsoft Windows Server 2019 Datacenter
OsOperatingSystemSKU : DatacenterServerEdition
OsArchitecture : 64-bit
WindowsVersion : 1809
WindowsBuildLabEx : 17763.1.amd64fre.rs5_release.180914-1434
OsLanguage : en-US
OsMuiLanguages : {en-US}

Version and build of PowerShell the target node is running

Name Value

PSVersion 5.1.17763.2183
PSEdition Desktop
PSCompatibleVersions {1.0, 2.0, 3.0, 4.0...}
BuildVersion 10.0.17763.2183
CLRVersion 4.0.30319.42000
WSManStackVersion 3.0
PSRemotingProtocolVersion 2.3
SerializationVersion 1.1.0.1

Version of the DSC module that was used ('dev' if using current dev branch)

Latest as installed by PS (8.5.0)

Start with the DSC_Computer resource and reproduce the RenamePC configuration using a name longer than 15 characters. Review how the existing Name property validates and applies computer names; done means a separate property supports names up to 63 characters without changing existing behavior.