I am getting extra parameters added to my querystring. What causes this? Can this be avoided?
Certain BrowserHawk tests, such as detecting disabled settings, screen size, connection speed, and plugins, require a round trip between BrowserHawk and the client.
By default BrowserHawk adds a bhcp parameter to the query string so that it can keep track of whether it is in the first pass or second pass of its test.
You can change this default behavior by specifying a different requestType parameter when making the extended property check.
However, each requestType has its own advantages and disadvantages. Generally the best approach is to use the default settings, but you should explore these other options to see if one is more suitable for your environment.
For more information on the differences between requestTypes see the topic on Detecting Extended Properties in the documentation.