The simplest way to find out what is the DNS’s IP or the other way round, use host
www.yahoo.com is an alias for www.yahoo.akadns.net.
www.yahoo.akadns.net has address 220.127.116.11
18.104.22.168.in-addr.arpa domain name pointer f1.www.vip.sp1.yahoo.com.
But usually if I want to find out IP of a site I ll use ping instead, anyway host did a nice job.