Chromecast devices (some? all?) have Google's public DNS servers hard coded. Paul Vixie wrote a nice rant about catching these devices trying to bypass his local DNS servers.
All Chrome based browsers have 8.8.8.8 8.8.4.4 hardcoded under the guise of "helping resolve navigation errors", except its not helping anyone but Google in gathering statistics. Domains like hls.ttvnw.net (no A record) receive perfectly valid DNS reply (NOERROR, response code 0, DNS Query completed successfully) but trigger this feature and call hardcoded Google DNS resolver. Even domains that dont exist at all and browser receives valid response (NXDOMAIN, response code 3, Domain name does not exist) trigger to snitch on the user to hardcoded Google DNS resolver. No errors, google called.