s1.domainkey.u9256.wl007.sendgrid.net has no NS records.
NS records for this zone are defined at wl007.sendgrid.net.
NS records for this zone are defined at wl007.sendgrid.net.
Question and response
Question
dig s1.domainkey.u9256.wl007.sendgrid.net. NS
Answer
The response has no answer records.
Authority
wl007.sendgrid.net. 1800 SOA aisha.ns.cloudflare.com. dns.cloudflare.com. 2399761628 10000 2400 604800 1800
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0