My understanding is that if you bid on a bunch of URL variations such as ww.domain.com, w.domain.com, etc..... your creative will pop on all of them and you'll just be bidding against yourself
But...
When I compare my stats in 50onRed to my tracker, the number of hits are about the same, and the same IP's do not show up over and over
But let's assume this is the case, that my creative does pop on each. How do I know which URL I should be targeting?
On 50 on red you can either bid on the domain or on the keyword.
If you decide on domain targeting for example: domain.com. That will basically cover every possible variation of that domain. For instance: sub.domain.com or domain.com/dir/index.html
If you decide to target via keyword then it will just pull related domains/content according to that keyword.
So its an either or thing basically, otherwise you would compete against yourself.
What I like to do is target via keyword and then I blacklist all the domains that are not working for that specific keyword and I keep the ones that do.
Hope that helped