Apex domains cannot have CNAME records.
Question and response
Question
dig email.rr.com. NS
Answer
email.rr.com. 5 NS dns6.rr.com.
email.rr.com. 5 NS dns2.rr.com.
email.rr.com. 5 NS dns1.rr.com.
email.rr.com. 5 NS dns5.rr.com.
email.rr.com. 5 NS dns3.rr.com.
Authority
The response has no authority records.
Additional
dns1.rr.com. 5 A 69.134.7.5
dns2.rr.com. 5 A 69.134.147.5
dns3.rr.com. 5 A 69.134.7.6
dns5.rr.com. 5 A 69.134.7.7
dns6.rr.com. 5 A 76.85.228.83
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0