vBulletin allows you to create and submit an XML sitemap to your favorite search engines and website management tools. This facilitates easier indexing of your site and with various tools can even tell you if there are problems with the content on your site. You can find the options for this here: Settings > Options > XML Sitemap
Enable Automatic Sitemap Generation
When enabled this tells vBulletin to generate your sitemaps automatically via the Scheduled Task Manager. If you have a large forum, you may want to leave this disabled as it can be a time consuming task. Even if this is enabled, you can always generate your sitemap files manually by clicking on Rebuild Sitemap. Default Value: No
Automatic Sitemap Generation Frequency (Days)
If automatic sitemap generation is enabled, this option controls the number of days between automatic builds. Default Value: 14
Default Sitemap Priority
The default priority for content in the XML Sitemap. This may be configured on a per-content basis in the XML Sitemap group. Only a limited amount of content should be listed in the sitemap as a high priority, so you shouldn't set this value too high. Default Value: 0.5
Automatic Sitemap Search Engine Submission
Allows you to select one or more search engines to submit your sitemap to. Options include Google, Yahoo!, Bing!/Live Search, Ask.com, and Moreover. Default Value: All selected.
Sitemap File Path
XML sitemap data must be written to the filesystem to function. Enter the full path to the directory the files should be written to. Do not include a trailing slash. This directory must be writable by the webserver. It also must be accessible via a web browser. Default Value: <blank>
URLs Per Page
Enter the number of URLs that will be processed per page (and placed in each sitemap file). Note that only one type of content will be written to a file, so it is possible that there will be files that have less URLs than the number specified here.
Enter a value no larger than 50,000. Larger values may cause more performance impact while the sitemap is being generated. Default Value: 30000