Architecting on AWS Certification Architecting on AWS Certification High Availability & Fault Tolerance 3

Question 1

Which AWS service enables you to create a pilot-light disaster recovery strategy by maintaining a minimal version of your environment running in a secondary Region?

Accepted Answer

AWS Elastic Disaster Recovery

Answer

AWS Elastic Disaster Recovery (DRS) continuously replicates source servers to a staging area and can quickly scale up a full environment in a secondary Region during a disaster.

Question 2

Which CloudWatch metric would an architect monitor to detect that an Application Load Balancer has no healthy targets available?

Accepted Answer

HealthyHostCount

Answer

The HealthyHostCount metric reports the number of targets the load balancer considers healthy; a value of 0 means no healthy targets are available.

Question 3

An application must maintain session state even if the EC2 instance serving a user is replaced. Which solution achieves this with the least application change?

Accepted Answer

Store sessions in Amazon ElastiCache

Answer

Storing session data in ElastiCache externalizes state from EC2 instances so any instance can serve returning users regardless of which instance previously handled them.

Question 4

What RTO (Recovery Time Objective) characteristic distinguishes a warm standby DR strategy from a pilot light strategy?

Accepted Answer

Warm standby has a shorter RTO because a scaled-down but fully functional environment is already running

Answer

In warm standby, a fully functional but scaled-down replica is always running, so failover only requires scaling up rather than starting services from scratch.

Question 5

Which AWS Global Infrastructure feature ensures that an EC2 instance placed in a specific Availability Zone is physically isolated from instances in other AZs within the same Region?

Accepted Answer

AZ physical separation

Answer

Each Availability Zone is a physically distinct location with independent power, cooling, and networking, providing fault isolation from other AZs in the Region.

Architecting on AWS Certification Practice Test

Architecting on AWS Certification Practice Test

Architecting on AWS Certification Architecting on AWS Certification High Availability & Fault Tolerance 3