Question and response
Question
dig _spf.smtp.com. TXT
Answer
_spf.smtp.com. 3600 TXT "v=spf1 ip4:192.40.160.0/19 ip4:74.91.80.0/20 ~all"
Authority
smtp.com. 3600 NS ns-1304.awsdns-35.org.
smtp.com. 3600 NS ns-1999.awsdns-57.co.uk.
smtp.com. 3600 NS ns-5.awsdns-00.com.
smtp.com. 3600 NS ns-735.awsdns-27.net.
Additional
. 0 OPT ; payload 4096, xrcode 0, version 0, flags 0