Each AWS Region contains several Availability Zones (AZs): one or more data centers with independent power, cooling and networking, connected to each other by low-latency links. A resilient web tier runs in at least two AZs, so the loss of one data center, or a whole AZ, does not take the application down. Three services make that practical: Elastic Load Balancing (ELB) spreads traffic across healthy targets, Amazon EC2 Auto Scaling keeps the right number of healthy instances running, and health checks tie the two together. This combination appears in a large share of SAA-C03 resilience questions.
Keep reading for free
Create a free StudyToCert account to read the rest of this lesson: 7 more sections, 6 key terms, a real-world example, an exam tip and self-check questions. Every lesson, lab and practice test is free with an account.