updates.opendns.com has no CNAME records.
Question and response
Question
dig updates.opendns.com. NS
Answer
The response has no answer records.
Authority
opendns.com. 2765 SOA auth1.opendns.com. noc.opendns.com. 1771851257 16384 2048 1048576 2560
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0