A network system for an expandable distributed core architecture (“DCA”) includes multiple spine switches, multiple leaf switches coupled thereto, and a plurality of interconnections coupling each of the spine switches to each of the leaf switches. Servers, storage, and other system items and resources can be coupled to the leafs via downlinks and uplinks. Each of the plurality of spine switches includes at least one unused spine port that is reserved for a future expansion of the DCA in order to accommodate the addition of at least one other separate leaf switch to the at least one unused spine port. Additional ports can be unused and reserved for future expansion additions of more leafs and/or more spines. Also, a computing system assists in the design of the specific number and configuration of spines, leafs and interconnections based upon user inputs regarding current and future system needs.