u13219.wl220.sendgrid.net has no NS records.
NS records for this zone are defined at wl220.sendgrid.net.
NS records for this zone are defined at wl220.sendgrid.net.
Question and response
Question
dig u13219.wl220.sendgrid.net. NS
Answer
The response has no answer records.
Authority
wl220.sendgrid.net. 1800 SOA aisha.ns.cloudflare.com. dns.cloudflare.com. 2399269388 10000 2400 604800 1800
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0