Apex domains cannot have CNAME records.
Question and response
Question
dig glipac.ch. NS
Answer
glipac.ch. 5 NS ans1.glipac.ch.
glipac.ch. 5 NS ans2.glipac.com.
glipac.ch. 5 NS ans3.glipac.eu.
glipac.ch. 5 NS anycast26.irondns.net.
glipac.ch. 5 NS ans5.glipac.ch.
glipac.ch. 5 NS ans4.glipac.io.
glipac.ch. 5 NS anycast104.irondns.eu.
Authority
The response has no authority records.
Additional
ans1.glipac.ch. 5 A 193.108.91.218
ans5.glipac.ch. 5 A 95.100.173.64
ans1.glipac.ch. 5 AAAA 2600:1401:2:0:0:0:0:da
ans5.glipac.ch. 5 AAAA 2600:1480:d800:0:0:0:0:40
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0