Apex domains cannot have CNAME records.
Question and response
Question
dig ossnet.lv. NS
Answer
ossnet.lv. 5 NS ns3.ossnet.lv.
ossnet.lv. 5 NS ns1.ossnet.lv.
ossnet.lv. 5 NS ns2.ossnet.lv.
Authority
The response has no authority records.
Additional
ns1.ossnet.lv. 5 A 212.70.186.21
ns2.ossnet.lv. 5 A 212.70.186.22
ns3.ossnet.lv. 5 A 139.162.138.172
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0