Apex domains cannot have CNAME records.
Question and response
Question
dig csolve.net. NS
Answer
csolve.net. 5 NS ns6.vianet.ca.
csolve.net. 5 NS ns5.vianet.ca.
csolve.net. 5 NS ns4.vianet.ca.
csolve.net. 5 NS ns1.vianet.ca.
csolve.net. 5 NS ns3.vianet.ca.
csolve.net. 5 NS ns2.vianet.ca.
Authority
The response has no authority records.
Additional
ns1.vianet.ca. 5 A 209.91.128.30
ns2.vianet.ca. 5 A 204.187.89.10
ns3.vianet.ca. 5 A 209.91.174.60
ns4.vianet.ca. 5 A 204.187.88.5
ns5.vianet.ca. 5 A 162.219.54.2
ns6.vianet.ca. 5 A 162.219.55.2
ns5.vianet.ca. 5 AAAA 2620:10a:80eb:0:0:0:0:2
ns6.vianet.ca. 5 AAAA 2620:10a:80ec:0:0:0:0:2
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0