Default [Q] Windows Phone Ad Server IP?

Is it possible to get the IPs or domain names of the WP ad servers? I tried the known xbox ad servers, but they didn't work. Tested with Microsoft Mahjong and Microsoft Minesweeper. Didn't find anything via the search either.

EDIT: Doesn't know if that matters, but I tried it via changing the DNS Servers of my Router via OpenDNS and blocked
these. But that didn't change anything.