Harav Dovid Ostroff, born in Johannesburg, South Africa, has been teaching Hilchos Shabbos to people all over the world since 2001. He spent his yeshiva years in Yeshivas Kol Torah under the leadership of Hagaon Rav Shlomo Zalman Auerbach zt”l, with whom he had a very close relationship. To this day, Harav Dovid learns b’chavrusa with Rav Ezriel Auerbach (which he has done since 1994). Harav Dovid was tested on Hilchos Shabbos by both Rav Stern of Bnei Brak and the Rabbanut. Rav Ostroff was tested on Hilchos Nidah by Hagaon Rav Moshe Halberstam zt”l and the Rabbanut. He served apprenticeships under Rav Menachem Mendel Fuchs (Ramot, Yerushalayim) followed by Rav Vozner’s Bais Hora’ah (Bnei Brak), after which Hagaon Harav Sternbuch, shlit”a granted Rav Ostroff the heter hora’ah to pasken shailos. Since 1996, he also serves as a Moreh Hora’ah under the auspices of Rav Sternbuch, shlit”a.