Can I use Adsense as back-up ads?
 

Some ad networks have options to show other ads if there are no ads available. Can I use Adsense the back-up ads for these networks? One good example is Chitika. If Chitika has no available ads, they can either fill the space with a solid color, collapse the space or display ads from other networks. Can I use Adsense as back-up? Is it against Adsense TOS?

I think you can.
Adsense TOS says you cannot use any other contextual ad network along with adsense within same page at the same time.
but you can use them in same page at different time or at different pages at same time.
BTW Chitika is not a contextual ad network so you can use chitika along with adsene at the same time without violating Adsense TOS.

yes you can,.. but I not recommended that. since google doesn't like to be 2nd http://s.dpstatic.com/smilies/smile.png lol

You should update your information, it's been several YEARS this rule has changed..

So what's the current rule then?

The one in adsense policies, it's better I don't tell you so you can read them again. It's not a waste of time.

I will read it some time~~~