o3.mail.teamwork.com has no NS records.
NS records for this zone are defined at teamwork.com.
NS records for this zone are defined at teamwork.com.
Question and response
Question
dig o3.mail.teamwork.com. NS
Answer
The response has no answer records.
Authority
teamwork.com. 900 SOA ns-743.awsdns-28.net. awsdns-hostmaster.amazon.com. 1 7200 900 1209600 86400
Additional
. 0 OPT ; payload 4096, xrcode 0, version 0, flags 0