mail.sansan.com has no NS records.
NS records for this zone are defined at sansan.com.
NS records for this zone are defined at sansan.com.
Question and response
Question
dig u1903435.wl.sendgrid.net. NS
Answer
The response has no answer records.
Authority
wl.sendgrid.net. 1800 SOA aisha.ns.cloudflare.com. dns.cloudflare.com. 2397809148 10000 2400 604800 1800
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0