HttpWebRequest hang while calling ROUND-ROBIN DNS

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VB

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I have multiple Linux servers so we created common DNS for load balancing

if I call any individual server then we got response quickly but if I call common DNS then it request get hang on below line

Using reqStream As Stream = req.GetRequestStream()

below I mention my function to which is working fine with individual server

Dim resp As System.Net.WebResponse = Nothing
Dim req As System.Net.WebRequest = System.Net.WebRequest.Create(address)
Dim byteData() As Byte
            CType(req, HttpWebRequest).KeepAlive = False
            CType(req, HttpWebRequest).Headers.Add("HTTP_ACCEPT_ENCODING", "gzip,deflate,sdch")

            req.Method = "POST"
            req.Timeout = 60000
            req.ContentType = "application/json"

            byteData = Encoding.UTF8.GetBytes(strRequestJSON)
            req.ContentLength = byteData.Length

            Using reqStream As Stream = req.GetRequestStream()
                reqStream.Write(byteData, 0, byteData.Length)
                reqStream.Close()
            End Using

            Dim myHttpWebResponse As HttpWebResponse = CType(req.GetResponse(), HttpWebResponse)

            Return New System.IO.StreamReader(myHttpWebResponse.GetResponseStream(), System.Text.Encoding.UTF8).ReadToEnd()

Please help or suggest if you face same issue with ROUND-ROBIN DNS