mx1.dreamhost.com has no NS records.
NS records for this zone are defined at dreamhost.com.
NS records for this zone are defined at dreamhost.com.
Question and response
Question
dig mx1.dreamhost.com. NS
Answer
The response has no answer records.
Authority
dreamhost.com. 300 SOA ns1.dreamhost.com. hostmaster.dreamhost.com. 2026022300 1454 1800 1209600 300
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0