u250297.wl048.sendgrid.net has no NS records.
NS records for this zone are defined at wl048.sendgrid.net.
NS records for this zone are defined at wl048.sendgrid.net.
Question and response
Question
dig u250297.wl048.sendgrid.net. NS
Answer
The response has no answer records.
Authority
wl048.sendgrid.net. 1800 SOA aisha.ns.cloudflare.com. dns.cloudflare.com. 2399342999 10000 2400 604800 1800
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0