Apex domains cannot have CNAME records.
Question and response
Question
dig lb. NS
Answer
lb. 5 NS b.ns.lb.
lb. 5 NS nabil.ns.lb.
lb. 5 NS s.ns.lb.
lb. 5 NS t.ns.lb.
lb. 5 NS n.ns.lb.
lb. 5 NS i.ns.lb.
lb. 5 NS r.ns.lb.
lb. 5 NS m.ns.lb.
lb. 5 NS w.ns.lb.
Authority
The response has no authority records.
Additional
b.ns.lb. 159961 A 147.28.0.39
i.ns.lb. 68844 A 77.72.229.254
m.ns.lb. 68844 A 78.141.235.25
n.ns.lb. 159961 A 158.38.0.181
r.ns.lb. 159961 A 105.16.170.1
s.ns.lb. 159961 A 105.16.115.1
t.ns.lb. 159961 A 139.84.235.208
w.ns.lb. 159961 A 203.178.141.64
nabil.ns.lb. 159961 A 185.91.97.18
b.ns.lb. 159961 AAAA 2001:418:1:0:0:0:0:39
i.ns.lb. 68844 AAAA 2a01:3f0:0:306:0:0:0:53
m.ns.lb. 68844 AAAA 2001:19f0:7401:890d:5400:4ff:fea8:9ffa
n.ns.lb. 159961 AAAA 2001:700:0:503:0:0:aa:5302
r.ns.lb. 159961 AAAA 2c0f:feb0:c:1:0:0:1:1
s.ns.lb. 159961 AAAA 2c0f:feb0:2:1:0:0:1:8001
t.ns.lb. 159961 AAAA 2a05:f480:3000:205f:5400:4ff:fea4:e565
w.ns.lb. 159961 AAAA 2001:200:0:2:0:0:53:1
nabil.ns.lb. 159961 AAAA 2a05:e380:2:4:0:0:0:2
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0