Question and response
Question
dig smtp-rog.mail.yahoo.com. NS
Answer
smtp-rog.mail.yahoo.com. 5 CNAME smtp-rog.mail.a03.yahoodns.net.
Authority
a03.yahoodns.net. 300 SOA yf1.a1.b.yahoo.net. hostmaster.yahoo-inc.com. 1772596873 30 30 86400 300
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0