hit-block.opendns.com has no CNAME records.
Question and response
Question
dig hit-block.opendns.com. NS
Answer
The response has no answer records.
Authority
opendns.com. 4732 SOA auth1.opendns.com. noc.opendns.com. 1772483730 16384 2048 1048576 2560
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0