Apex domains cannot have CNAME records.
Question and response
Question
dig static.cable.qlnet.ch. NS
Answer
static.cable.qlnet.ch. 5 NS ns4.qlns.net.
static.cable.qlnet.ch. 5 NS ns1.qlns.ch.
static.cable.qlnet.ch. 5 NS ns2.qlns.ch.
Authority
The response has no authority records.
Additional
ns1.qlns.ch. 5 A 212.60.60.128
ns2.qlns.ch. 5 A 212.60.62.128
ns4.qlns.net. 5 A 212.60.60.128
ns1.qlns.ch. 5 AAAA 2001:1a88:10:fffe:0:0:0:1
ns2.qlns.ch. 5 AAAA 2001:1a88:10:fffe:0:0:0:2
ns4.qlns.net. 5 AAAA 2001:1a88:10:fffe:0:0:0:1
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0