Amazon Web Services Updated SAA-C03 Exam Questions and Answers by soraya

https://aws.amazon.com/premiumsupport/knowledge-center/dynamodb-high-latency/

Amazon DynamoDB Accelerator (DAX) is a fully managed in-memory cache for DynamoDB that improves the performance of DynamoDB tables by up to 10 times and provides microsecond level of response time at any scale. It is compatible with DynamoDB API operations and requires minimal code changes to use1. By configuring DAX for the new messages table, the solution can reduce the latency for reading new messages with minimal application changes.

B. Add DynamoDB read repticas to handle the increased read load. Update the application to point to the read endpoint for the read replicas. This solution will not work, as DynamoDB does not support read replicas as a feature. Read replicas are available for Amazon RDS, not for DynamoDB2.

C. Double the number of read capacity units for the new messages table in DynamoDB. Continue to use the existing DynamoDB endpoint. This solution will not meet the requirement of reading new messages with as little latency as possible, as increasing the read capacity units will only increase the throughput of DynamoDB, not the performance or latency3.

D. Add an Amazon ElastiCache for Redis cache to the application stack. Update the application to point to the Redis cache endpoint instead of DynamoDB. This solution will not meet the requirement of minimal application changes, as adding ElastiCache for Redis will require significant code changes to implement caching logic, such as querying cache first, updating cache after writing to DynamoDB, and invalidating cache when needed.

Reference URL: https://aws.amazon.com/dynamodb/dax/

This answer is correct because it provides high availability at the node level and at the Region level for the ElastiCache for Redis solution. A Multi-AZ Redis replication group consists of a primary cluster and up to five read replica clusters, each in a different Availability Zone. If the primary cluster fails, one of the read replicas is automatically promoted to be the new primary cluster. A Redis replication group with shards enables partitioning of the data across multiple nodes, which increases the scalability and performance of the solution. Each shard can have one or more replicas to provide redundancy and read scaling.

References:

• https://docs.aws.amazon.com/AmazonElastiCache/latest/red-ug/AutoFailover.html
• https://docs.aws.amazon.com/AmazonElastiCache/latest/red-ug/Shards.html

This answer is correct because it provides redundancy for the VPN connection between the Management VPC and the data center. If one customer gateway device or one VPN tunnel becomes unavailable, the traffic can still flow over the second customer gateway device and the second VPN tunnel. This way, the single point of failure in the VPN connection is mitigated.

References:

• https://docs.aws.amazon.com/vpn/latest/s2svpn/vpn-redundant-connection.html
• https://www.trendmicro.com/cloudoneconformity/knowledge-base/aws/VPC/vpn-tunnel-redundancy.html

https://aws.amazon.com/premiumsupport/knowledge-center/multivalue-versus-simple-policies/