dns.smartguard.io has no CNAME records.
Question and response
Question
dig dns.smartguard.io. NS
Answer
The response has no answer records.
Authority
smartguard.io. 2247 SOA ns1.smartguard.io. hostmaster.smartguard.io. 2025041801 14400 3600 1209600 3600
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0