mx4.vianet.ca has no NS records.
NS records for this zone are defined at vianet.ca.
NS records for this zone are defined at vianet.ca.
Question and response
Question
dig mx4.vianet.ca. NS
Answer
The response has no answer records.
Authority
vianet.ca. 900 SOA gwn.vianet.ca. hostmaster.vianet.ca. 1772046733 600 900 604800 900
Additional
The response has no additional records.