Apex domains cannot have CNAME records.
Question and response
Question
dig pk. NS
Answer
PK. 5 NS root-s.pknic.pk.
PK. 5 NS root-c2.pknic.pk.
PK. 5 NS root-e.pknic.pk.
PK. 5 NS root-c1.pknic.pk.
Authority
The response has no authority records.
Additional
root-e.pknic.pk. 92241 A 107.6.178.178
root-s.pknic.pk. 58164 A 119.81.34.90
root-c1.pknic.pk. 79161 A 185.159.197.160
root-c2.pknic.pk. 170195 A 185.159.198.160
root-c1.pknic.pk. 79161 AAAA 2620:10a:80aa:0:0:0:0:160
root-c2.pknic.pk. 170195 AAAA 2620:10a:80ab:0:0:0:0:160
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0