how google crawl last modified time in site map xml

suppose my websites name is www.somewebsite.com

i have a php file in www.somewebsite.com/sitemap.php, this php file will be executed by cron This php file will create a site map for my site www.somewebsite.com/sitemap.xml

<url>
  <loc>http://www.somewebsite.com/some_stupid_content</loc>
  <lastmod>2010-12-10</lastmod>
 </url>

In the above code u can see last modified time is 2010-12-10 , which is not true.

What my sitemap.php file is doing is that, it shows the last modified time of content.php file from my content management system (content.php is used to create all the content(some_stupid_content) in my site)

so the last modified time in my xml file is wrong.

Should i make lastmod as the time in which my cron execute (i know this time also can we wrong). My question is will it create some problem开发者_运维知识库 for google to crawl.

Just make lastmod points the right last modifying time. Google bots does not consider that entry, they know how to crowl in a clever way.

But you can make a change to make the sitemap.xml to show right lastmod.

The sitemap won't do you much good for Google sake even if you update it manually. What really matters to Google is human understandable update of site content. If you have that freshly update in your sitemap.php You will be considered higher rank by Google