smtp.cloud.itcsa.net has no NS records.
NS records for this zone are defined at cloud.itcsa.net.
NS records for this zone are defined at cloud.itcsa.net.
Question and response
Question
dig smtp.cloud.itcsa.net. NS
Answer
The response has no answer records.
Authority
cloud.itcsa.net. 300 SOA ns-cloud-c1.googledomains.com. cloud-dns-hostmaster.google.com. 1 21600 3600 259200 300
Additional
. 0 OPT ; payload 512, xrcode 0, version 0, flags 0