smtp.esupportmail.com has no NS records.
NS records for this zone are defined at esupportmail.com.
NS records for this zone are defined at esupportmail.com.
Question and response
Question
dig smtp.esupportmail.com. NS
Answer
The response has no answer records.
Authority
esupportmail.com. 1800 SOA ara.ns.cloudflare.com. dns.cloudflare.com. 2397534589 10000 2400 604800 1800
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0