Apex domains cannot have CNAME records.
Question and response
Question
dig newsletter.ipserverone.com. NS
Answer
newsletter.ipserverone.com. 4 NS pdns1.ipserverone.com.
newsletter.ipserverone.com. 4 NS pdns2.ipserverone.com.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0