zimbra.workcloud.tech has no CNAME records.
Question and response
Question
dig zimbra.workcloud.tech. NS
Answer
The response has no answer records.
Authority
workcloud.tech. 1747 SOA jaime.ns.cloudflare.com. dns.cloudflare.com. 2396874501 10000 2400 604800 1800
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0