A method for improving client subnet efficiency by equivalence class aggregation includes receiving a Domain Name System (DNS) query from a client, determining, based on predetermined class criteria, that the client is associated with an equivalency class, searching a cache associated with the equivalence class for an answer corresponding to the DNS query, and upon locating the answer, serving the answer to the client. If it is determined that the cache does not include the answer, the method proceeds with querying, by a recursive server, an authoritative server using client subnet data associated with the equivalence class, receiving the answer from the authoritative server, storing the answer to the cache associated with the equivalency class, and serving the answer to the client. The client subnet data may include a representative CIDR block, the representative CIDR block being used to make queries on behalf of all clients associated with the equivalence class.