A search engine receives from a client a representation of a first object that
was returned by a web server to the client in response to a request from the client.
The search engine receives from the web server a second object in response to an
identical request from the search engine, and compares the representation of the
first object to a representation of the second object. The web server is determined
to be cloaked if the representation of the first object does not match the representation
of the second object. Typically, the client receives a URL embedded in a response
to a search request submitted to the search engine. A toolbar operating in conjunction
with the web browser on the client processes the URL. The processing includes:
directing the web browser to obtain an object corresponding to the URL from a web
server addressed by the URL; converting the object to a feature vector; and delivering
the feature vector and the URL back to the search engine.
