s2._domainkey.metrocom.cr has no NS records.
NS records for this zone are defined at metrocom.cr.
NS records for this zone are defined at metrocom.cr.
Question and response
Question
dig s2.domainkey.u14174057.wl058.sendgrid.net. NS
Answer
The response has no answer records.
Authority
wl058.sendgrid.net. 1800 SOA aisha.ns.cloudflare.com. dns.cloudflare.com. 2399866830 10000 2400 604800 1800
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0