"Do Not Track" just means that the browser sends the DNT
header with every request, that's all it is. It does not provide any additional client functionality. The header has a value of 1
when enabled, and either sends 0
or omits the header when disabled.
You, as a web application developer, do not need to concern yourself with the DNT
header unless you are involved in developing visitor tracking systems, in which case the higher-ups in your organisation will tell you if you should respect the header or not.
In ASP.NET you can retrieve the header like so:
String doNotTrack = Request.Headers["DNT"];
if( doNotTrack == "1" ) {
// Do not track the user
// ...whatever that means.
}