Check Internet Connection

To check for an Internet connection in .NET, we can use GetIsNetworkAvailable method defined in the System.Net.Network-Information namespace. But it returns a Boolean value that denotes whether any network connection is available and does not say about Internet connectivity. To make sure we also have Internet access, the reliable method is to attempt to ping a host

Imports System.Net.NetworkInformation 
Public Function IsConnectedToInternet() As Boolean
    Dim host As String = http://www.c-sharpcorner.com
    Dim result As Boolean = False
    Dim p As Ping = New Ping()
    Try
        Dim reply As PingReply = p.Send(host, 3000)
        If reply.Status = IPStatus.Success Then
            Return True
        End If
    End Try
    Return result
End Function

Or we can use a simple API function InternetGetConnectedState. This function takes two arguments:

The first one is an integer used with out keyword, which means that after calling the function, the variable will contain an integer that describes the connection state.

The second one is a reserved variable that must be set to 0.

Imports System
Imports System.Runtime
Imports System.Runtime.InteropServices
Public Class InternetCS
    'Creating the extern function...
<DllImport("wininet.dll")> _
private extern static Boolean InternetGetConnectedState( Integer Description, Integer ReservedValue) 
    'Creating a function that uses the API function...
    Public Shared Function IsConnectedToInternet() As Boolean
        Dim Desc As Integer
        Return InternetGetConnectedState(Desc, 0)
    End Function
End Class