As your online business grows it becomes important to bring your services as close to the front user as possible. There are two sides of DNS resolution that play important role here. The first one is deployment of multiple DNS servers in key locations around the globe to reduce DNS resolution times. The second one is geo split DNS (variation of split horizon DNS service) or DNS load balancing. This is used with multiple web servers (most likely could servers) in different locations to reflect your consumers' distribution to primarily direct a web request to the front user's closest web server, but it does redistribute work load on servers as well.