Our URL categorization team maintains huge database of URL's, by running scripts which repeatedly crawl entire web and classify the domains in appropriate categories. The URL's categories can be re-classified based on the new content scanned by web-crawlers. In today's dynamic web, where thousands of new domains popping up every day - the database cannot be most upto-date always - for the same reason the new URL categorization engine (Cisco IronPort web usage controls) performs dynamic categorization of the domains (if there are not part of the database). As the database gets updates dynamically, the device continues to fetch new URL categorization updates from update servers.
