Apex domains cannot have CNAME records.
Question and response
Question
dig cid.com. NS
Answer
cid.com. 5 NS ns2.cid.de.
cid.com. 5 NS ns1.cid.com.
Authority
The response has no authority records.
Additional
ns1.cid.com. 5 A 192.174.68.100
ns2.cid.de. 5 A 176.97.158.100
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0