exchange.delska.com has no CNAME records.
Question and response
Question
dig exchange.delska.com. NS
Answer
The response has no answer records.
Authority
delska.com. 372 SOA nola.ns.cloudflare.com. dns.cloudflare.com. 2397682011 10000 2400 604800 1800
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0