c116.c5341538.usw1.send.mailgun.net has no NS records.
NS records for this zone are defined at c5341538.usw1.send.mailgun.net.
NS records for this zone are defined at c5341538.usw1.send.mailgun.net.
Question and response
Question
dig c116.c5341538.usw1.send.mailgun.net. NS
Answer
The response has no answer records.
Authority
c5341538.usw1.send.mailgun.net. 300 SOA ns-cloud-e1.googledomains.com. cloud-dns-hostmaster.google.com. 1 21600 3600 259200 300
Additional
. 0 OPT ; payload 512, xrcode 0, version 0, flags 0