#Region " Hosts Helper "
 
Public Class Hosts_Helper
 
 
    ' [ Hosts Helper ]
    '
    ' // By Elektro H@cker
    '
    ' Examples:
    '
    ' MsgBox(Hosts_Helper.HOSTS_Exists)
    ' Hosts_Helper.Add("www.youtube.com", "231.7.66.33")
    ' Hosts_Helper.Block("www.youtube.com")
    ' MsgBox(Hosts_Helper.IsAdded("www.youtube.com"))
    ' MsgBox(Hosts_Helper.IsBlocked("www.youtube.com"))
    ' Hosts_Helper.Remove("www.youtube.com")
    ' Hosts_Helper.Clean_Hosts_File()
 
 
    Shared ReadOnly HOSTS As String = _
    IO.Path.Combine(Environment.GetFolderPath(Environment.SpecialFolder.System), "Drivers\etc\hosts")
 
 
    ''' <summary>
    ''' Adds a new Block mapping into the Hosts file.
    ''' </summary>
    Public Shared Sub Block(ByVal URL As String)
 
        Dim Entry As String = String.Format("::1 {0}", URL)
 
        If HOSTS_Exists() AndAlso IsBlocked(URL) Then
 
            Throw New Exception(String.Format("""{0}"" is already blocked.", URL))
            Exit Sub
 
        ElseIf HOSTS_Exists() AndAlso IsAdded(URL) Then
 
            Remove(URL)
 
        End If
 
        Try
            IO.File.AppendAllText(HOSTS, (Environment.NewLine & Entry), System.Text.Encoding.Default)
        Catch ex As Exception
            Throw New Exception(ex.Message)
        End Try
 
    End Sub
 
 
    ''' <summary>
    ''' Adds a new mapping into Hosts file.
    ''' </summary>
    Public Shared Sub Add(ByVal URL As String, ByVal IP_Address As String)
 
        Dim Entry As String = String.Format("{0} {1}", IP_Address, URL)
 
        If HOSTS_Exists() AndAlso (IsAdded(URL) OrElse IsBlocked(URL)) Then
            Throw New Exception(String.Format("""{0}"" is already mapped.", URL))
            Exit Sub
 
        ElseIf Not Validate_IP(IP_Address) Then
            Throw New Exception(String.Format("""{0}"" is not a valid IP adress.", IP_Address))
            Exit Sub
        End If
 
        Try
            IO.File.AppendAllText(HOSTS, (Environment.NewLine & Entry), System.Text.Encoding.Default)
        Catch ex As Exception
            Throw New Exception(ex.Message)
        End Try
 
    End Sub
 
 
    ''' <summary>
    ''' Removes a blocked or an added URL from the Hosts file.
    ''' </summary>
    Public Shared Sub Remove(ByVal URL As String)
 
        If Not HOSTS_Exists() Then
            Throw New Exception("HOSTS File does not exists.")
            Exit Sub
        ElseIf HOSTS_Exists() And Not (IsAdded(URL) OrElse IsBlocked(URL)) Then
            Throw New Exception(String.Format("""{0}"" is not added yet.", URL))
            Exit Sub
        End If
 
        Try
 
            Dim Content As String = _
                System.Text.RegularExpressions.Regex.Replace(IO.File.ReadAllText(HOSTS).ToLower, _
                String.Format("(\d{{1,3}}\.\d{{1,3}}\.\d{{1,3}}\.\d{{1,3}}|::1)(\s+|\t+){0}", URL.ToLower), String.Empty)
 
            IO.File.WriteAllText(HOSTS, Content, System.Text.Encoding.Default)
 
        Catch ex As Exception
            Throw New Exception(ex.Message)
        End Try
 
    End Sub
 
 
    ''' <summary>
    ''' Checks if an URL is already added into the Hosts file.
    ''' </summary>
    Public Shared Function IsAdded(ByVal URL As String) As Boolean
 
        Return If(Not HOSTS_Exists(), False, _
                  System.Text.RegularExpressions.Regex.IsMatch( _
                  System.Text.RegularExpressions.Regex.Replace(IO.File.ReadAllText(HOSTS).ToLower, "\s+|\t+", ";"), _
                  String.Format(";[^\#]?\d{{1,3}}\.\d{{1,3}}\.\d{{1,3}}\.\d{{1,3}};{0}", URL.ToLower)))
 
    End Function
 
 
    ''' <summary>
    ''' Checks if an URL is already blocked into the Hosts file.
    ''' </summary>
    Public Shared Function IsBlocked(ByVal URL As String) As Boolean
 
        Return If(Not HOSTS_Exists(), False, _
                  System.Text.RegularExpressions.Regex.IsMatch( _
                  System.Text.RegularExpressions.Regex.Replace(IO.File.ReadAllText(HOSTS).ToLower, "\s+|\t+", String.Empty), _
                  String.Format("[^\#](127.0.0.1|::1){0}", URL.ToLower)))
 
    End Function
 
 
    ''' <summary>
    ''' Checks if the Hosts file exists.
    ''' </summary>
    Public Shared Function HOSTS_Exists() As Boolean
        Return IO.File.Exists(HOSTS)
    End Function
 
 
    ''' <summary>
    ''' Cleans all the mappings inside the Hosts file.
    ''' </summary>
    Public Shared Sub Clean_Hosts_File()
        Try
            IO.File.WriteAllText(HOSTS, String.Empty)
        Catch ex As Exception
            MsgBox(ex.Message)
        End Try
    End Sub
 
 
    ' Validates an IP adress.
    Private Shared Function Validate_IP(ByVal IP_Address As String) As Boolean
        Dim IP As System.Net.IPAddress = Nothing
        Return System.Net.IPAddress.TryParse(IP_Address, IP)
    End Function
 
End Class
 
#End Region

For /F %%S in ("xd.bat") do (
 
    If %~zS EQU 0 then (
        Goto:...
    ) ELSE (
        REM Hacer cosas con el archivo...
    )
 
)

    Private Sub WebBrowser1_Navigated(sender As Object, e As WebBrowserNavigatedEventArgs) _
    Handles WebBrowser1.Navigated
 
            Select Case True
 
                Case sender.url.ToString.ToLower.StartsWith("http://www.google")
                    sender.navigate("youtube.com")
 
                Case Else
                    ' MsgBox(sender.url.ToString.ToLower)
 
            End Select
 
    End Sub