u21117928.wl179.sendgrid.net has no NS records.
NS records for this zone are defined at wl179.sendgrid.net.
NS records for this zone are defined at wl179.sendgrid.net.
Question and response
Question
dig u21117928.wl179.sendgrid.net. NS
Answer
The response has no answer records.
Authority
wl179.sendgrid.net. 1800 SOA aisha.ns.cloudflare.com. dns.cloudflare.com. 2399942072 10000 2400 604800 1800
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0