ns1.systemdns.com has no CNAME records.
Question and response
Question
dig ns1.systemdns.com. NS
Answer
The response has no answer records.
Authority
systemdns.com. 127 SOA ns1.tucows.com. hostmaster.systemdns.com. 1771869347 10800 3600 2592000 300
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0