Final answer:
When a Web page changes, crawler-based directories update their indexes and databases automatically to reflect the change.
Step-by-step explanation:
When a Web page changes, crawler-based directories update their indexes and databases automatically to reflect the change. Crawler-based directories use automated software programs called web crawlers or spiders to browse the internet and collect information about web pages. These spiders visit websites periodically and update their index with the latest information, ensuring that their search results are up to date.