Apex domains cannot have CNAME records.
Question and response
Question
dig geoflexcloud.com. NS
Answer
geoflexcloud.com. 4 NS ns1.pcdog.ch.
geoflexcloud.com. 4 NS ns3.pcdog.ch.
geoflexcloud.com. 4 NS ns2.pcdog.ch.
geoflexcloud.com. 4 NS ns4.pcdog.ch.
Authority
The response has no authority records.
Additional
ns1.pcdog.ch. 4 A 46.232.182.145
ns2.pcdog.ch. 4 A 89.238.82.210
ns3.pcdog.ch. 4 A 178.62.42.142
ns4.pcdog.ch. 4 A 5.226.144.214
ns1.pcdog.ch. 4 AAAA 2a02:6201:2ee8:b680:0:0:91:1
ns2.pcdog.ch. 4 AAAA 2a00:1828:2000:568:0:0:0:53
ns3.pcdog.ch. 4 AAAA 2a03:b0c0:1:d0:0:0:4a6:3001
ns4.pcdog.ch. 4 AAAA 2a00:6340:2010:2800:0:0:0:214
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0