Question and response
Question
dig mail-us.atlassian.net. PTR
Answer
mail-us.atlassian.net. 5 CNAME atlassian.mail.e.sparkpost.com.
Authority
mail.e.sparkpost.com. 900 SOA ns-1031.awsdns-00.org. awsdns-hostmaster.amazon.com. 1 7200 900 1209600 86400
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0