resolver1.opendns.com has no CNAME records.
Question and response
Question
dig resolver1.opendns.com. NS
Answer
The response has no answer records.
Authority
opendns.com. 5384 SOA auth1.opendns.com. noc.opendns.com. 1772019580 16384 2048 1048576 2560
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0