u22591655.wl156.sendgrid.net has no NS records.
NS records for this zone are defined at wl156.sendgrid.net.
NS records for this zone are defined at wl156.sendgrid.net.
Question and response
Question
dig u22591655.wl156.sendgrid.net. NS
Answer
The response has no answer records.
Authority
wl156.sendgrid.net. 1800 SOA aisha.ns.cloudflare.com. dns.cloudflare.com. 2399587767 10000 2400 604800 1800
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0