Mobile networks are becoming increasingly popular as a means for distributing information to a large number of users. In comparison to wired networks, mobile networks are distinguished by a potentially much higher variability in client demand due to user mobility. Most previous content distribution techniques assume a static client demand distribution and, thus, may not perform well in mobile networks. This paper proposes and analyzes a Mobile Dynamic Content Distribution Network model, which takes demand variations into account to decide whether to replicate a content and whether to remove previously created replicas in order to minimize total network traffic. We develop two solutions to our model: an offline optimal, which provides an ideal lower-bound on the total traffic, and a practical heuristic online algorithm, which uses demand forecasting to make replication decisions. We provide a thorough evaluation of our solutions, comparing them against ACDN, the only previous dynamic c...