How optimization is achieved in DNS?

Two primary optimizations used in DNS and they are: replication and caching. All root servers is replicated; various copies of the server exist around the world. While a new site joins the internet, the site configures its local DNS server along with a list of root server. The site server uses any root server is most responsive at a provided point of time. Into DNS caching each server maintains a cache of names. When this looks up a new name, the server puts a copy of the binding in its cache. Before contacting other server to request a binding, the server checks its cache; when the cache have the answer the server uses the cached answer to produce a reply.