The no-image Image
In case there is no available image given a set of isbns and client configuration the Cover Image Resolver will return an HTTP redirect to the no-image image. The no-image image is a 1px by 1px transparent gif, so it can be included in the page without an unsightly broken image icon. All no-image images will be redirected to the same URL to make use of caching. In the case of a no-image, the HTTP redirect is temporary instead of permanent.