suggested fix for #900; Nick to review please

StackExchange.Redis/StackExchange/Redis/SocketManager.cs

@@ -125,7 +125,12 @@ private void Dispose(bool disposing)
         internal static Socket CreateSocket(EndPoint endpoint)
         {
             var protocolType = endpoint.AddressFamily == AddressFamily.Unix ? ProtocolType.Unspecified : ProtocolType.Tcp;
-            var socket = new Socket(endpoint.AddressFamily, SocketType.Stream, protocolType);
+            var addressFamily = endpoint.AddressFamily;
+            if (addressFamily == AddressFamily.Unspecified && endpoint is DnsEndPoint)
+            {   // default DNS to ipv4 if not specified explicitly
+                addressFamily = AddressFamily.InterNetwork;
+            }
+            var socket = new Socket(addressFamily, SocketType.Stream, protocolType);
             SocketConnection.SetRecommendedClientOptions(socket);
             return socket;
         }

TestConsole/Program.cs

@@ -6,7 +6,14 @@
 
 static class Program
 {
-    static async Task Main()
+    static void Main()
+    {
+        using (var muxer = ConnectionMultiplexer.Connect("localhost:6379", Console.Out))
+        {
+            muxer.GetDatabase().Ping();
+        }
+    }
+    static async Task Main2()
     {
         const int ClientCount = 150, ConnectionCount = 10;
         CancellationTokenSource cancel = new CancellationTokenSource();