core.ntc.net.pk has no CNAME records.
Question and response
Question
dig core.ntc.net.pk. NS
Answer
The response has no answer records.
Authority
ntc.net.pk. 575 SOA ns3.rapidcompute.com. dns-services\@cyber.net.pk. 2019031037 600 60 604800 600
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0