dns1.mastercard.com has no CNAME records.
Question and response
Question
dig dns1.mastercard.com. NS
Answer
The response has no answer records.
Authority
mastercard.com. 300 SOA dns2.mastercard.com. hostmaster.mastercard.com. 2011131179 14400 3600 2419200 300
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0