Unhandled Exception: System.Net.Sockets.SocketException: No such host is known
at System.Net.Dns.GetAddrInfo(String name)
at System.Net.Dns.InternalGetHostByName(String hostName, Boolean includeIPv6)
at System.Net.Dns.GetHostEntry(String hostNameOrAddress)
at Replace.Common.AsyncNetwork.AsyncServer.Accept(String host, Int32 port, Int32 outstanding, IAsyncInterface interface, Object user)
at Replace.Certification.Program.Main(String[] args)
this error is how to fix?