smtp.rockettemail.com has no NS records.
NS records for this zone are defined at rockettemail.com.
NS records for this zone are defined at rockettemail.com.
Question and response
Question
dig smtp.rockettemail.com. NS
Answer
The response has no answer records.
Authority
rockettemail.com. 300 SOA x.ns.joker.com. hostmaster.joker.com. 2024110687 14400 3600 1209600 300
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0