rdns2.xiolink.com has no NS records.
NS records for this zone are defined at xiolink.com.
NS records for this zone are defined at xiolink.com.
Question and response
Question
dig rdns2.xiolink.com. NS
Answer
The response has no answer records.
Authority
xiolink.com. 3600 SOA ns1.ral.hostedsolutions.com. hostmaster.hostedsolutions.com. 2018050466 900 600 86400 3600
Additional
. 0 OPT ; payload 1220, xrcode 0, version 0, flags 0