Apex domains cannot have CNAME records.
Question and response
Question
dig dslplus.net.PK. NS
Answer
dslplus.net.pk. 5 NS ns2.link.net.pk.
dslplus.net.pk. 5 NS ns.link.net.pk.
dslplus.net.pk. 5 NS ns1.link.net.pk.
Authority
The response has no authority records.
Additional
ns.link.net.pk. 5 A 210.2.185.3
ns1.link.net.pk. 5 A 210.2.183.71
ns2.link.net.pk. 5 A 210.2.177.246
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0