I am wondering if a DDoS attack of URL shortening services will render them unusable. This came to my mind when I gave a dummy URL to bit.ly and it replied back with a short URL.
So, if a service becomes popular, then a DDoS attack which tries to get short links for dummy URLs would quickly make the short URL space run out.
Will they, then, increase the shortened URL length? Or periodically clean the database to rid of dummy URLs?