Better details about when Googlebot last visited a page

Most people know that Googlebot downloads pages from web servers to crawl the web. Not as many people know that if Googlebot accesses a page and gets a 304 (Not-Modified) response to a If-Modified-Since qualified request, Googlebot doesn’t download the contents of that page. This reduces the bandwidth consumed on your web server.

When you look at Google’s cache of a page (for instance, by using the cache: operator or clicking the Cached link under a URL in the search results), you can see the date that Googlebot retrieved that page. Previously, the date listed for the page’s cache was the date Googlebot last successfully fetched the contents of the page. This meant that even if Googlebot visited a page very
recently, the cache date might be quite a bit older if the page hadn’t changed since the previous visit. This made it difficult for webmasters to use the cache date Google displays to determine Googlebot’s most recent visit. Consider the following example:

1. Googlebot crawls a page on April 12, 2006
2. Google’s cached version of that page notes that “This is G o o g l e’s cache of http://www.example.com/ as retrieved on April 12, 2006 20:02:06″
3. Periodically, Googlebot checks to see if that page has changed, and each time, receives a Not-Modified response. For instance, on August 27, 2006, Googlebot checks the page, receives a Not-Modified response, and therefore, doesn’t download the contents of the page.
4. On August 28, 2006, Google’s cached version of the page still shows the April 12, 2006 date — the date Google last downloaded the page’s contents, even though Googlebot last visited the day before.

Google recently changed the date they show for the cached page to reflect when Googlebot last accessed it (whether the page had changed or not). This should make it easier for you to determine the most recent date Googlebot visited the page. For instance, in the above example, the cached version of the page would now say “This is G o o g l e’s cache of http://www.example.com/ as retrieved on August 27, 2006 13:13:37 GMT.”