We examine the issue of disaster recovery after zonal outages in core networks, especially IP-over-WDM multi-layer networks. In particular, we consider the network design problem for a regional failure of circular area of radius R. Our goal is to design a network that can withstand a randomly located single failure of radius R. To this end, we formulate the problem as a constrained optimization problem whose solution for both IP-over-optical networks and pure ROADM-based networks is proposed. Subsequently, we develop an efficient heuristic based on a divide and conquer strategy that gives acceptable results. We also discuss the role of SDN in design and restoration of such networks. Simulation results are showcased over a core network topology thereby realizing the plausibility of such network design.