mail.siteground359.com has no NS records.
NS records for this zone are defined at siteground359.com.
NS records for this zone are defined at siteground359.com.
Question and response
Question
dig mail.siteground359.com. NS
Answer
The response has no answer records.
Authority
siteground359.com. 86400 SOA ns1.siteground359.com. mail.siteground359.com. 15 86400 7200 3600000 86400
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0