Apex domains cannot have CNAME records.
Question and response
Question
dig static.bbserv.nl. NS
Answer
static.bbserv.nl. 5 NS ns2.u-servers.net.
static.bbserv.nl. 5 NS ns1.u-servers.net.
Authority
The response has no authority records.
Additional
ns1.u-servers.net. 5 A 84.53.82.82
ns2.u-servers.net. 5 A 195.216.224.224
ns1.u-servers.net. 5 AAAA 2a02:120:320:851:0:0:1:53
ns2.u-servers.net. 5 AAAA 2001:67c:294:0:0:0:0:53
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0