u9973402.wl153.sendgrid.net has no NS records.
NS records for this zone are defined at wl153.sendgrid.net.
NS records for this zone are defined at wl153.sendgrid.net.
Question and response
Question
dig u9973402.wl153.sendgrid.net. NS
Answer
The response has no answer records.
Authority
wl153.sendgrid.net. 1800 SOA aisha.ns.cloudflare.com. dns.cloudflare.com. 2399285811 10000 2400 604800 1800
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0