216.104.233.80.
Question and response
Question
dig smtp01.blackhawk-net.com. PTR
Answer
smtp01.blackhawk-net.com. 300 PTR 216.104.233.80.
Authority
blackhawk-net.com. 172800 NS ns-1335.awsdns-38.org.
blackhawk-net.com. 172800 NS ns-1753.awsdns-27.co.uk.
blackhawk-net.com. 172800 NS ns-20.awsdns-02.com.
blackhawk-net.com. 172800 NS ns-930.awsdns-52.net.
Additional
. 0 OPT ; payload 4096, xrcode 0, version 0, flags 0