introduction of how private network of aws(vpc) works. e.g. how to communicate with outside components, how to assign the IP addresses, how you divide your vcp into the address spaces by the subnets, and etc.
k-d tree is a binary search tree that represents the node value as k-dimensional coordinates, and how the left and right branches go depends on the layer of tree (e.g. 1: x, 2: y, 3: z, 4: x, ...). This data structure is typically used for nearest neighbor algorithm.