Forum Moderators: martinibuster
My theory is that it has to do with which pages mediabot is hitting. You may want to make a standard of inserting the new Robots.txt command for Google-Mediabot into all of your pages so that no matter what the display URL is, you will get refreshed often.
Like I said, in my case I got PSAs, so I guess be a little happy that you are still at least getting some sort of ads.
AdSense Tips [google.com] page can tell you more about the command
My theory is that it has to do with which pages mediabot is hitting.
The most important thing for every publisher to understand is that if the URL is different, Google will consider it a different page. www.domain.tld is considered a different host than domain.tld (and rightfully so).
I suspect that it's a combination of the following:
1. The Mediapartners bot hasn't visited the page on one of the hosts yet, but has on the other.
2. Due to changes in the content of the page between when Mediapartners visited it last on one host vs. the other, its algorithms made a different decision about the page in terms of whether to show ads on it and if so which kind of ads.
3. Criteria such as link text to pages pointing to that *exact* URL from *both* within that site and from external pages.
4. For some reason the Mediapartners bot couldn't access the page on one of the hosts (prevented by .htaccess, blocked via robots.txt, site down, some other access control reason, etc.).
The best solution? In my opinion, unless there's a very good reason for maintaining domain.tld and host.domain.tld it's advisable to redirect one to the other using an HTTP status 301 (permanent) redirect. *Lots* of problems will be solved by doing so. There can b e situations where a webmaster may prefer not to do so, but that's neither here nor there.
You may want to make a standard of inserting the new Robots.txt command for Google-Mediabot into all of your pages so that no matter what the display URL is, you will get refreshed often.
I'm not sure what you mean by "new". Can you elaborate? AFAIK, there's nothing new about the two lines recommended to be added to the robots.txt file (see tip #4 [google.com]). Unless you already have a robots.txt file for your host which either blocks all user agents from all pages, all user agents from some pages or Mediapartners from some/all pages, then by default Mediapartners will assume it's allowed to visit all of the pages on that host.
Also, for any newbies be sure to name the file robots.txt (case sensitive), robots.txt should appear in the root of your site (not in your page HTML which is what BennyBlanco's post seemed to suggest) and the frequency with which Mediapartners visits a page has nothing to do with the contents or presence of robots.txt.
apache and we have no root level access.
Using the following solution to do an HTTP 301 (permanent) redirect from domain.tld to host.domain.tld, Apache must be installed with the Apache module mod_rewrite loaded, DNS for domain.tld must point to the same IP as host.domain.tld and the following must be added to either a global Apache configuration file by your host or within .htaccess in the document root of the site (will only work if your host has configured Apache to allow the following Apache directives to be used in .htaccess):
RewriteEngine On
RewriteCond %{HTTP_HOST}!^host.domain.tld
RewriteRule ^/(.*) [host.domain.tld...] [R=301,L]
The following directive is also required, but is likely already in place based on current behavior for your site.
ServerAlias domain.tld (assuming ServerName host.domain.tld, if reverse is true then ServerAlias host.domain.tld)
If you need further assistance, I suggest posting to the Apache Web Server Forum [webmasterworld.com] and mentioning this post/thread since this discussion isn't really AdSense related any longer.