We pick i.root-servers.net, one of the 13 root servers (1), and ask it about mail.christianpost.co.id and learn that id is delegated to four name servers (2), so we ask sec3.apnic.net where we learn that co.id is delegated to eight name servers, including d.dns.id (3), so we ask that one and learn that christianpost.co.id is delegated to two name servers (4), so we ask ns.chtoday.com and get the following answer:
mail.christianpost.co.id has one IP number (222.122.226.216). Mail.koohouse.com, mail.lebunnybleu.com, mail.deographics.co.kr, mail.jkn.co.kr and mail.guyber.co.kr point to the same IP....