Apex domains cannot have CNAME records.
Question and response
Question
dig blmpb.com. NS
Answer
blmpb.com. 2 NS ns-telecom.volc-dns.net.
blmpb.com. 2 NS ns-mobile.volc-dns.com.
blmpb.com. 2 NS ns2.volc-dns.net.
blmpb.com. 2 NS ns1.volc-dns.com.
blmpb.com. 2 NS ns-unicom.volc-dns.com.
Authority
The response has no authority records.
Additional
ns2.volc-dns.net. 2 A 39.97.243.225
ns2.volc-dns.net. 2 A 47.103.69.110
ns2.volc-dns.net. 2 A 47.115.127.205
ns-telecom.volc-dns.net. 2 A 119.97.179.131
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0