Public Sub DoPing()
    ' count for iterations - should be move into a class
    Static iteration As Integer
    Dim msg As String
    Caption = "Ping - " + txtRemoteHost
    
    ' update window title
    If Not Caption = frmMain.Caption Then frmMain.Caption = Caption
    ping.RemoteHost = txtRemoteHost
    ping.Timeout = txtTimeout
    ping.PacketSize = txtPacketSize
    ping.DoHostResolution = chkDoHostResolution.Value
    ping.Blocking = chkBlocking.Value
    ping.DoPing
    iteration = iteration + 1
    
    ' output formatted message
    If ping.RemoteHostIP = "" Then
        msg = "Could not resolve host " + ping.RemoteHost
    End If
    
    Select Case ping.ReplyCode
    Case 0
        msg = ping.PacketSize & " bytes received from {" & _
        ping.RemoteHostName & "} <" & _
        ping.RemoteHostIP & ">, (" & _
        ping.RemoteHost & ") icmp_seq = " & _
        iteration & _
        ", time = " & ping.Delay & " ms, ttl = " & ping.TimeToLive
    Case Else
        msg = ping.ErrorString(ping.ReplyCode) + ": reply code=" & ping.ReplyCode
    End Select
    txtOutput = txtOutput + msg + vbCrLf
    txtOutput.SelStart = Len(txtOutput.Text)
    
    
End Sub