mrtg.alentus.com has no NS records.
NS records for this zone are defined at alentus.com.
NS records for this zone are defined at alentus.com.
Question and response
Question
dig mrtg.yeg01.ca.as4250.net. NS
Answer
The response has no answer records.
Authority
as4250.net. 3601 SOA dns1.registrar-servers.com. hostmaster.registrar-servers.com. 1770744691 43200 3600 604800 3601
Additional
. 0 OPT ; payload 4096, xrcode 0, version 0, flags 0