Apex domains cannot have CNAME records.
Question and response
Question
dig membrane.com. NS
Answer
membrane.com. 1 NS parsifal.membrane.com.
membrane.com. 1 NS hugin.membrane.com.
Authority
The response has no authority records.
Additional
hugin.membrane.com. 1 A 70.63.16.147
parsifal.membrane.com. 1 A 98.114.102.244
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0