Question: How does Sitemap Creator determine the date a page was last modified?
Answer: As Sitemap Creator crawls your website, it generates a snapshot of each page and compares it to the snapshot that was taken the previous time page was crawled. If the snapshot is different, Sitemap Creator knows the page has been updated and updates the Last Modified date accordingly. If the snapshot is the same, it uses the date when the previous snapshot was taken.
The first time you run Sitemap Creator on your site each page will have the current date as the “Last Modified” time. Each additional time you crawl your site the pages will be compared against this initial run. It’s normal for the “Last Modified” date to be the current date for all pages the first time you run Sitemap Creator on a website.
For best results, Sitemap Creator should be configured to crawl your site on a scheduled basis. This will ensure that your sitemap is up-to-date and pages that are modified regularly are reflected in your sitemap.
Note: If your website provides the “Last-Modified” HTTP header, this value will be used instead of the internally generated Last Modified date.