mx.sylche.com has no NS records.
NS records for this zone are defined at sylche.com.
NS records for this zone are defined at sylche.com.
Question and response
Question
dig mx.sylche.com. NS
Answer
The response has no answer records.
Authority
sylche.com. 3600 SOA dns.sylche.com. hostmaster.sylche.com. 1481019683 43200 3600 604800 3600
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0