Help please {No Such host is known} error

Question

I am using the following code under windows 2016 Standard Server IIS10 - .NET Framework 4.0

Goal to obtain the remote client computer name. 

 

C# Code Behind  

Default.aspx.cs 

var RemoteClient_DevineName = System.Net.Dns.GetHostEntry(HttpContext.Current.Request.ServerVariables["REMOTE_HOST"]).HostName;

Result is this error message below

 

Server Error in '/' Application.

No such host is known

Description: An unhandled exception occurred during the execution of the current web request. Please review the stack trace for more information about the error and where it originated in the code.

Exception Details: System.Net.Sockets.SocketException: No such host is known

Source Error:

An unhandled exception was generated during the execution of the current web request. Information regarding the origin and location of the exception can be identified using the exception stack trace below.

Stack Trace:

[SocketException (0x2af9): No such host is known]

System.Net.Dns.InternalGetHostByAddress(IPAddress address, Boolean includeIPv6) +2943591

System.Net.Dns.GetHostEntry(String hostNameOrAddress) +8625688

 

Thank you for your help.