The If-Range header, which specifies that only the specified range of the requested resource should be sent, if the client's cached copy is current.
Syntax
HttpRequestHeader IfRange
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