Question and response
Question
dig mail.duoservers.com. TXT
Answer
mail.duoservers.com. 3600 TXT "v=spf1 a mx a:mail.duoservers.com ip4:198.23.56.33 ~all"
Authority
duoservers.com. 3600 NS dns1.duoservers.com.
duoservers.com. 3600 NS dns2.duoservers.com.
Additional
dns1.duoservers.com. 3600 A 198.23.53.28
dns2.duoservers.com. 3600 A 198.23.53.30