A central controller and a method for separation of traffic processing in a software defined network (SDN). The method comprises: identifying, based on at least one zoning trigger parameter, a potential cyber-attack; triggering a zoning mode for mitigating the potential cyber-attack; dynamically allocating, based on a load profile, a first group of computing resources of a computing farm to a trusted zone and a second group of computing resources to an un-trusted zone; assigning the computing resources in the first group with a first address and the computing resources in the second group with a second address, wherein only the second address is advertised; and causing at least one network element in the SDN to divert incoming traffic to the first group and to the second group of computing resources based on a plurality of zoning rules implemented by the at least one network element.