In the Google Webmaster technical guidelines the following statement is made "Make sure your web server supports the If-Modified-Since HTTP header. This feature allows your web server to tell Google whether your content has changed since we last crawled your site. Supporting this feature saves you bandwidth and overhead."

How do we add this functionality to DotNetNuke?

7/8/2011 - DNN 5.6.2
To cathal connolly: You are talking about .. in IIS, right-click on a website name & choose Properties on the menu... which opens the website's Properties window.
On the HTTP Headers tab it normally says "expire after 30 days".
What Mike Lawell is talking about is a specific If-Modified-Since HTTP header in DNN.
Since DNN websites are drawn from a SQL DB, it is likely impossible for IIS to identify a date when a Tab has been changed.

The Importance of having a correct & current If-Modified-Since header is shown on https://www.google.com/support/webmasters/bin/answer.py?answer=35769

Evidence that DNN does not currently support the reporting of when a tab has been updated is by taking the test at http://www.feedthebot.com/tools/if-modified/
and his basic info is at http://www.feedthebot.com/ifmodified.html

So will the DNN Core Staff please consider this as a Feature Request to include the If-Modified-Since header on all page requests.

BarryZ
www.1usa.com

After updating to DNN 5.6.2, in the Text-html module, when you are editing, there now appears a Version History with a date last edited... at the bottom of the edit screen before you save your changes. If there is only one Text-html module on a page, or if there are multiple modules on a page, wouldn't it be possible to update the Page's Page Settings properties with a date every time you click to update a module on a page?
Yes, it won't be accurate for all pages, but at least it would show the search engines that the website is being edited from time to time.

The date on the Page Settings properties can then be published as the If-Modified-Since header. Partial search engine compliance is better than none.

Each Page Settings tab already has a "Last Updated By System On 6/18/2011 8:14:46 AM"
Maybe this alone can be published as the If-Modified-Since header ??

BarryZ
1USA