By default IIS redirects to a given domain and/or application.
The web page and query string can be transferred to the destination url by using the respective parameters $S and $Q.
will lead to
In IIS 6 the checkbox "Exact Url" will avoid appending the web page to the query string.
In order to achieve that behaviour in IIS 7 you have to first enable "Redirect all requests to exact destination" and append the sufix $S$Q to the url.
If you rely in the automatic url redirection of IIS (by default, w/o $S$Q in url) the query string is actually cut.