ok,
let's suppose that usually provides the most appropriate environment for placing the dns servers and their co-infrastructure. taking it only technically, providing the connectivity for the ixp is a detail (to announce or not to announce). maybe the ixp could allocate a 'stub' subnet - separate from the transit subnet - and provide a voluntary mlpa to all the hosted isps. this would not break the isp policies on announcing the transit ixp subnet. all these are details.
i see a space for another topic in this thread - updating the dns infrastrucure a bit. to be more specific:
- would the ixp-located tld dns servers server only a small set of tld's each? if so, would it be region-based or agreement-based?
- would it be worth the effort starting a project similar to irr that would serve as a common source for dns configurations?
it'd be nice to hear your oppinions