ELB is designed to handle unlimited requests per second by gradually increasing load pattern.You can configure EC2 instances and load balancers to accept traffic.
You can add/remove load balancers according to your requirement without affecting the overall flow of information.
You can enable Elastic Load Balancing within a single Availability Zone or across multiple zones for even more consistent application performance.
It cannot handle sudden increase in requests like online exams, online trading, etc.