Apex domains cannot have CNAME records.
Question and response
Question
dig inet.fi. NS
Answer
inet.fi. 5 NS ns2-fin.global.sonera.fi.
inet.fi. 5 NS ns1-fin.global.sonera.fi.
inet.fi. 5 NS ns1-swe.global.sonera.se.
inet.fi. 5 NS ns2-usa.global.sonera.net.
Authority
The response has no authority records.
Additional
ns1-fin.global.sonera.fi. 5 A 193.210.18.31
ns1-swe.global.sonera.se. 5 A 213.64.37.28
ns2-fin.global.sonera.fi. 5 A 195.156.148.158
ns2-usa.global.sonera.net. 5 A 213.64.37.29
ns1-fin.global.sonera.fi. 5 AAAA 2001:2060:ffdd:a01:0:0:0:53
ns1-swe.global.sonera.se. 5 AAAA 2001:2040:c000:63:0:0:0:1
ns2-fin.global.sonera.fi. 5 AAAA 2001:2060:ffdd:a02:0:0:0:53
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0