RhinoFish - 8:29 pm on Mar 3, 2013 (gmt 0)
It's a live auction, so they'd need to know the IPs that make your page dynamically 404... hence the IP entry area.
Your work around posed here, ends up needing to know the IP -before- they show the ad.
If they don't understand that it is the IP causing the 404, they'll assume it's down for many, and shut off your ads for bad landing pages. Once you tell them it's for certain IPs, they'd need to know which ones, to prevent serving your ads to people from those IPs. See, it's a circle.