u8418715.wl216.sendgrid.net has no NS records.
NS records for this zone are defined at wl216.sendgrid.net.
NS records for this zone are defined at wl216.sendgrid.net.
Question and response
Question
dig u8418715.wl216.sendgrid.net. NS
Answer
The response has no answer records.
Authority
wl216.sendgrid.net. 1800 SOA aisha.ns.cloudflare.com. dns.cloudflare.com. 2399720343 10000 2400 604800 1800
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0