sg1._domainkey.korehosting.net has no NS records.
NS records for this zone are defined at korehosting.net.
NS records for this zone are defined at korehosting.net.
Question and response
Question
dig sg1.domainkey.u33381347.wl098.sendgrid.net. NS
Answer
The response has no answer records.
Authority
wl098.sendgrid.net. 1800 SOA aisha.ns.cloudflare.com. dns.cloudflare.com. 2399920106 10000 2400 604800 1800
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0