Complex sentence: There was a near exponential growth of domain registrations over that period however some of that was due to Domain tasting a practice by which millions of domains would be registered for a limited period and only those generating sufficient revenue from PPC advertising would be retained.
Split into simpler sentences: There was a near exponential growth of domain registrations over that period. Some of that was due to Domain tasting a practice by which millions of domains would be registered for a limited period and only those generating sufficient revenue from PPC advertising would be retained.