Apex domains cannot have CNAME records.
Question and response
Question
dig 194-222.80.34.192.in-addr.arpa. NS
Answer
194-222.80.34.192.in-addr.arpa. 4 NS revp1.bostonfiber.net.
194-222.80.34.192.in-addr.arpa. 4 NS revp2.bostonfiber.net.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0