Parsing arp.exe - WaitForExit(60000) times out - vb.net

Question

I'm trying to parse arp.exe's output to get the MAC address for a computer. I'm able to parse ping.exe and obtain the IP address but for some reason arp.exe appears to never exit. If I remove the arguments I it exits almost instantly. If I run the command myself in command prompt it outputs the result in less than one second. I'm not sure why it's not working.
Public Function DNSLookup(ByVal dnsName As String)
#If Not Debug Then
Try
#End If
Dim p As New Process
With p.StartInfo
.FileName = "ping.exe"
.Arguments = "-n 1 -4 " + dnsName 'Send 1 echo/packet (-n 1) and force IPv4 (-4)
.CreateNoWindow = True
.RedirectStandardOutput = True
.RedirectStandardError = True
.UseShellExecute = False
End With
p.Start()
If p.WaitForExit(5000) Then
'Find and parse "Reply from xxx.xxx.xxx.xxx: bytes=xx time=xms TTL=xxx"
Dim result As String = p.StandardOutput.ReadToEnd 'Read the result from the command line
Dim i As Integer = result.IndexOf("Reply from ") + 11 '11 is the length of "Reply from "
result = result.Substring(i, result.IndexOf(": bytes=") - i) 'Get the IP from the command line output
Return result
Else
Throw New System.Exception("DNS lookup failed. Timeout exceeded")
End If
#If Not Debug Then
Catch ex As Exception
MsgBox(ex.Message, MsgBoxStyle.Critical)
End Try
#End If
End Function
Public Function GetMACAddress(ByVal dnsName As String)
Dim ip As String = DNSLookup(dnsName)
#If Not Debug Then
Try
#End If
Dim arp As New Process
With arp.StartInfo
.FileName = "arp.exe"
.Arguments = "-a" ' | find " + Chr(34) + ip + Chr(34) 'Example: arp -a | find "192.168.0.1"
.CreateNoWindow = True
.RedirectStandardOutput = True
.RedirectStandardError = True
.RedirectStandardInput = False
.UseShellExecute = False
End With
arp.Start()
If arp.WaitForExit(60000) Then
MsgBox(arp.StandardOutput.ReadToEnd)
Else
Throw New System.Exception("ARP lookup failed. Timeout exceeded")
End If
Return 1 '### TO DO: Return parsed MAC address
#If Not Debug Then
Catch ex As Exception
MsgBox(ex.Message, MsgBoxStyle.Critical)
End Try
#End If
End Function

Answer 1

I'm not sure why this wasn't working with the arguments just set to "-a" last night as when I ran it this morning that worked. However I realised that the reason my full argument wasn't working is because "| find" isn't an argument recognised by arp.exe. To solve it I've used cmd.exe /c arp. Updated code below works:
Public Function GetMACAddress(ByVal dnsName As String)
Dim ip As String = DNSLookup(dnsName)
#If Not Debug Then
Try
#End If
Dim arp As New Process
With arp.StartInfo
.FileName = "cmd.exe"
.Arguments = "/c arp -a | find " + Chr(34) + ip + Chr(34) 'Example: arp -a | find "192.168.0.1"
.CreateNoWindow = False
.RedirectStandardOutput = True
.RedirectStandardError = True
.RedirectStandardInput = False
.UseShellExecute = False
End With
arp.Start()
If arp.WaitForExit(5000) Then
MsgBox(arp.StandardOutput.ReadToEnd)
Else
Throw New System.Exception("ARP lookup failed. Timeout exceeded")
End If
Return 1 '### TO DO: Return parsed IP address
#If Not Debug Then
Catch ex As Exception
MsgBox(ex.Message, MsgBoxStyle.Critical)
End Try
#End If
End Function