_spf.kakaocorp.com has no NS records.
NS records for this zone are defined at kakaocorp.com.
NS records for this zone are defined at kakaocorp.com.
Question and response
Question
dig _spf.kakaocorp.com. NS
Answer
The response has no answer records.
Authority
kakaocorp.com. 300 SOA ns.kakaocorp.com. root.kakaocorp.com. 1667984524 1800 600 2419200 300
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0