mail.roothere.com has no NS records.
NS records for this zone are defined at roothere.com.
NS records for this zone are defined at roothere.com.
Question and response
Question
dig mail.roothere.com. NS
Answer
The response has no answer records.
Authority
roothere.com. 1800 SOA brenda.ns.cloudflare.com. dns.cloudflare.com. 2396916328 10000 2400 604800 1800
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0