A quick tip (script) how to list all the .Net (major) versions of a list of machines.

$serverListFile = "<Path to file>\computers.txt";
$computers = Get-Content -path $serverListFile

$BASEDOTNETPATH = "\c$\Windows\Microsoft.NET\Framework\"

function CheckNet45($computerName){
  $NETROOTKEY = "SOFTWARE\\Microsoft\\NET Framework Setup\\NDP\\v4"
  $keyname = $NETROOTKEY + "\\Full"
  try{
    $reg = [Microsoft.Win32.RegistryKey]::OpenRemoteBaseKey("LocalMachine", $computerName)
    if ($reg -ne $null){
      if ($reg.OpenSubKey($keyname).GetValue("Version").ToString().StartsWith("4.5")){
        return $True
      }
    }
  }
  catch {
    #do nothing
  }
  return $False
}

foreach($computer in $computers)
{
  $computer
  $ok = Test-Connection $computer -Count 1 -Quiet
  if ($ok) {
    $computerBasePath = "\\" + $computer + $BASEDOTNETPATH
    $versionStr = ""
    if (Test-Path ($computerBasePath + "v1.0.3705")){
      $versionStr = $versionStr + "1.0,"
    }
    if (Test-Path ($computerBasePath + "v1.1.4322")){
      $versionStr = $versionStr + "1.1,"
    }
    if (Test-Path ($computerBasePath + "v2.0.50727")){
      $versionStr = $versionStr + "2.0,"
    }
    if (Test-Path ($computerBasePath + "v3.0")){
      $versionStr = $versionStr + "3.0,"
    }
    if (Test-Path ($computerBasePath + "v3.5")){
      $versionStr = $versionStr + "3.5,"
    }
    if (Test-Path ($computerBasePath + "v4.0.30319")){
      $versionStr = $versionStr + "4.0,"

      if (CheckNet45($computer)){
        $versionStr = $versionStr + "4.5,"
      }
    }
    $versionStr = $versionStr.TrimEnd(',')
    "  Installed version(s): " + $versionStr

  }
  else{
   " Is not pingable!"
  }
}

All you have to do is create a text file with a list of machine names (one name per line). It does assume you have Admin rights so you can access the C$ share and read the remote registries.