There are a few online advertisement opt-out services such as:
Each of those pages connect to several advertising hubs, presumably request a 3rd party cookie to determine if tracking is enabled or not. This process is repeated several times. Screenshot:
I'd like to understand this transaction, how it works for determining status at a given provider, and how the non-track attribute is maintained.
- Does each vendor have a standard way of determining tracking? (e.g. a ./well-known/ RFC based URL?)
- Is the query to that vendor a GET or POST
- What is the return value, and header information?
- Is the return value and header information standardized in any way?
- If a cookie is set on the client, is it a unique identifier of sorts, or is it a generic "don't track me" request?