This policy setting allows you to configure scanning mapped network drives.If you enable this setting mapped network drives will be scanned.If you disable or do not configure this setting mapped network drives will not be scanned.
Policy path:
Windows Components\Windows Defender\Scan 
Scope:
Machine 
Supported on:
At least Windows Server 2012 Windows 8 or Windows RT 
Registry settings:
HKLM\Software\Policies\Microsoft\Windows Defender\Scan!DisableScanningMappedNetworkDrivesForFullScan 
Filename:
WindowsDefender.admx 
