Apex domains cannot have CNAME records.
Question and response
Question
dig dstatic.de. NS
Answer
dstatic.de. 2 NS matias.ns.cloudflare.com.
dstatic.de. 2 NS josephine.ns.cloudflare.com.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0