smtp.webmercs.com has no NS records.
NS records for this zone are defined at webmercs.com.
NS records for this zone are defined at webmercs.com.
Question and response
Question
dig smtp.webmercs.com. NS
Answer
The response has no answer records.
Authority
webmercs.com. 300 SOA ns-cloud-c1.googledomains.com. cloud-dns-hostmaster.google.com. 21 21600 3600 1209600 300
Additional
. 0 OPT ; payload 512, xrcode 0, version 0, flags 0