Apex domains cannot have CNAME records.
Question and response
Question
dig suddenlink.net. NS
Answer
suddenlink.net. 5 NS authns1.alticeusa.com.
suddenlink.net. 5 NS authns1.alticeusa.net.
Authority
The response has no authority records.
Additional
authns1.alticeusa.com. 5 A 167.206.13.20
authns1.alticeusa.net. 5 A 167.206.12.12
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0