Between peers: "Habari!" and the greeted answers, "Nzuri!".
Between peers: "Hujambo?" (Are you fine?) and the greeted answers, "Sijambo!" (I'm fine!)
Young to older: "Shikamoo!" (originally it meant "I touch your feet" as a sign of respect) and the greeted answers, "Marahabaa!" (I acknowledge your respect!).