How to Ensure High Availability and Uniform Traffic Distribution for EC2 Instances and Elastic Load Balancer
Question
An application is being set up by launching EC2 Instances and an Elastic Load balancer.
It needs to be ensured that the application is made highly available and also a uniform distribution of traffic across the various backend nodes.
How can you accomplish this? Choose 2 answers from the options given below.
Answers
Explanations
Click on the arrows to vote for the correct answer
A. B. C. D.Correct Answers: B and C.
For maximum availability, ensure that the Instances are placed across multiple availability zones.
The AWS Documentation mentions the following.
When you enable an Availability Zone for the load balancer, Elastic Load Balancing creates a load balancer node in the Availability Zone.
By default, each load balancer node distributes traffic across the registered targets in its Availability Zone only.
If you enable cross-zone load balancing, each load balancer node distributes traffic across the registered targets in all enabled Availability Zones.
Options A and D are incorrect since the resources need to be created in the same region.
For more information on the Network Load Balancer, please visit the below URLs-
https://docs.aws.amazon.com/elasticloadbalancing/latest/network/introduction.html https://docs.aws.amazon.com/elasticloadbalancing/latest/classic/enable-disable-crosszone-lb.html https://aws.amazon.com/about-aws/whats-new/2018/02/network-load-balancer-now-supports-cross-zone-load-balancing https://docs.aws.amazon.com/elasticloadbalancing/latest/userguide/how-elastic-load-balancing-works.htmlThe correct answers to the question are B and C.
B. Ensure that the Instances are launched across multiple availability zones: Availability Zones (AZs) are distinct data centers within a region that are isolated from failures in other AZs. By launching instances across multiple AZs, you can ensure high availability for your application. If one AZ becomes unavailable due to a natural disaster or other issues, the instances in the other AZs will continue to handle traffic, providing high availability for the application.
C. Ensure that cross zone load balancing is enabled on the load balancer: Cross-zone load balancing is an Elastic Load Balancing feature that enables traffic to be evenly distributed across instances in all available AZs. When you enable cross-zone load balancing, the load balancer nodes route traffic to the healthy instances across all enabled AZs, regardless of which AZ the load balancer nodes are in. This provides a uniform distribution of traffic across the various backend nodes.
A. and D. are not the correct answers because:
A. Ensuring that the Instances are launched across multiple regions: While launching instances across multiple regions can provide disaster recovery capabilities, it is not the best way to ensure high availability for an application because there will be latency and data replication issues between the regions. Moreover, launching instances across multiple regions will increase the operational complexity and cost of the application.
D. Ensuring that the load balancer is created across multiple regions: Creating a load balancer across multiple regions is not a practical approach to ensure high availability for an application. There will be additional latency and complexity issues due to cross-region communication, and it may not provide uniform distribution of traffic across the various backend nodes. This approach is generally used for disaster recovery purposes.
