Zoe is a fashion designer who owns an online retail store. She was recently named ‘The Best Upcoming Fashion Designer of the Year’ by a highly popular fashion magazine. Due to this recognition, the web traffic to her site greatly increased. However, the server on which her website was housed could not handle the high amount of web traffic, which led to the crashing of the website. To resolve this issue, Zoe purchased two additional servers. Using a solution, she distributed the burden from the web traffic between the three servers, which helped in maximizing the efficiency of the servers. Which solution did Zoe use?