The Proxy-Authenticate header, which specifies that the client must authenticate itself to a proxy.
Syntax
HttpResponseHeader ProxyAuthenticate
Requirements
Namespace: System.Net
Assembly: System (in System.dll)
Assembly Versions: 2.0.0.0, 4.0.0.0
Since: .NET 2.0
Assembly: System (in System.dll)
Assembly Versions: 2.0.0.0, 4.0.0.0
Since: .NET 2.0