Published: Tuesday, March 4, 2008
The major search engines - Google, Yahoo! and Microsoft have officially announced the common support of a new protocol for cross-domain sitemap submission. This joint effort, dating back to November 2006 was officially adopted February 27, 2008.
This new standard will make it easier for webmasters to manage sitemaps across multiple domain hosts from a single domain host and letting search engines know the locations of sitemaps via the standardized robots.txt file picked up by search engine robots aka spiders.
Let's say for example you're the webmaster of multiple websites, www.mydomain.com and blog.mydomain.com for technical challenges or simply ease of management you may want to host both sitemaps under one domain host, for example: sitemaps.mydomain.com. Previously each sitemap would have needed to reside within each domain host however; with the new sitemap protocol - the sitemaps can now reside in the single domain host by simply including a common reference in the robots.txt file to establish a trusted relationship amongst the cross-domains.
Example reference for sitemaps in robots.txt file:
Sitemaps can be formatted in the standard sitemap XML, RSS and text format. The maximum recommended file size of robots.txt file should not exceed 1MB. When multiple sitemaps for domain include identical URLs metadata will be disregarded and only the URL will be examined by search engine bots. Sitemap files should not exceed 10MB in file size.