mail.totbb.com has no NS records.
NS records for this zone are defined at totbb.com.
NS records for this zone are defined at totbb.com.
Question and response
Question
dig mail.totbb.com. NS
Answer
The response has no answer records.
Authority
totbb.com. 900 SOA ns1.totonline.net. idc.totbb.net. 164 10800 3600 2419200 900
Additional
. 0 OPT ; payload 1220, xrcode 0, version 0, flags 0