dns.umbraco.io has no CNAME records.
Question and response
Question
dig dns.umbraco.io. NS
Answer
The response has no answer records.
Authority
umbraco.io. 876 SOA kara.ns.cloudflare.com. dns.cloudflare.com. 2398467652 10000 2400 604800 1800
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0