True it would be an issue for CPC/CPM campaigns but less so for CPA. Not sure what the solution would be for CPC/CPM - off the top of my head maybe a random CN

True it would be an issue for CPC/CPM campaigns but less so for CPA. Not sure what the solution would be for CPC/CPM - off the top of my head maybe a random CNAME that pointed to an ad-server controlled IP so they could cross-audit client IPs via a JS drop in file? Presumably ad-blockers would easily pick that up though.