Apex domains cannot have CNAME records.
Question and response
Question
dig imimobile.com. NS
Answer
imimobile.com. 5 NS ns-1170.awsdns-18.org.
imimobile.com. 5 NS ns-1660.awsdns-15.co.uk.
imimobile.com. 5 NS ns-162.awsdns-20.com.
imimobile.com. 5 NS ns-883.awsdns-46.net.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0