Using .NET ping to find devices on a network

I am finding that the PING function that ships in VB.NET seems to not always work on corporate networks, so I want to know what I can do to improve the probability of finding a host at an address.

The program allows the user to enter a list of addresses, and then it pings each address within that range and returns a table of devices

What I'm finding on large corporate networks is

1. The ping doesnt always find a device at an address even when a device is there
2. If I run it multi threaded, the probability of finding a device seems to reduce further
3. I have set default timeout to 100, and TTL=255, but so far I am only pinging each box once, whereas DOS ping obviosuly pings 4 times

Even with timeout upped to 5000, the problem exists.

I dont get many shots are large networks, so really I want to get it right next time..

My questions are:

(a) Would increasing the number of attempts from 1 to 4 or even more help ?
(b) Does it matter what size of data you send. I don't actually tell ping what data to send, so I suppose there must be a default byte array that it sends
(c) What other parameters can I set to get the absolute maximum probability of a ping response
(d) Multi threaded is definitely needed due to the time for each ping on a slow network, so any discussion on parameters related to multithreading would be appreciated




(c)

Public Function Ping(ByRef sAddress As String, ByRef sDataToSend As String, _
            ByVal lTimeOut As Integer, ByVal lTtl As Integer, _
            ByRef lResult As System.Net.NetworkInformation.IPStatus) As Integer
 
        Dim sn As New System.Net.NetworkInformation.Ping
        Dim re As System.Net.NetworkInformation.PingReply
        Dim op As New System.Net.NetworkInformation.PingOptions
 
        If sAddress = "" Then
            Return 0
        End If
 
        op.Ttl = lTtl
 
        Try
            re = sn.Send(sAddress, lTimeOut)
        Catch ex As System.Net.NetworkInformation.PingException
            Return 0
        Catch ex As System.Exception
            Return 0
        End Try
 
 
        lResult = re.Status
        If lResult = System.Net.NetworkInformation.IPStatus.Success Then
            Return 1
        Else
            Return 0
        End If
 
    End Function

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