Discuss Amazon SAA-C03 Exam Topic 2 Question 42

A company hosts a three-tier web application in the AWS Cloud. A Multi-AZ Amazon RDS for MySQL server forms the database layer. Amazon ElastiCache forms the cache layer. The company wants a caching strategy that adds or updates data in the cache when a customer adds an item to the database. The data in the cache must always match the data in the database.

Which solution will meet these requirements?

AImplement the lazy loading caching strategy

BImplement the write-through caching strategy.

CImplement the adding TTL caching strategy.

DImplement the AWS AppConfig caching strategy.

Suggested Answer: C

A public NAT gateway enables instances in a private subnet to send outbound traffic to the internet, while preventing the internet from initiating connections with the instances. A public NAT gateway requires an elastic IP address and a route to the internet gateway for the VPC. A private NAT gateway enables instances in a private subnet to connect to other VPCs or on-premises networks through a transit gateway or a virtual private gateway. A private NAT gateway does not require an elastic IP address or an internet gateway. Both private and public NAT gateways map the source private IPv4 address of the instances to the private IPv4 address of the NAT gateway, but in the case of a public NAT gateway, the internet gateway then maps the private IPv4 address of the public NAT gateway to the elastic IP address associated with the NAT gateway. When sending response traffic to the instances, whether it's a public or private NAT gateway, the NAT gateway translates the address back to the original source IP address.

Creating public NAT gateways in the same private subnets as the EC2 instances (option A) is not a valid solution, as the NAT gateways would not have a route to the internet gateway. Creating private NAT gateways in the same private subnets as the EC2 instances (option B) is also not a valid solution, as the instances would not be able to access the internet through the private NAT gateways. Creating private NAT gateways in public subnets in the same VPCs as the EC2 instances (option D) is not a valid solution either, as the internet gateway would drop the traffic from the private NAT gateways.

Therefore, the only valid solution is to create public NAT gateways in public subnets in the same VPCs as the EC2 instances (option C), as this would allow the instances to access the internet through the public NAT gateways and the internet gateway.Reference:

NAT gateways - Amazon Virtual Private Cloud

NAT gateway use cases - Amazon Virtual Private Cloud

Amazon Web Services -- Introduction to NAT Gateways

What is AWS NAT Gateway? - KnowledgeHut

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43 comments · newest first

Callie 11 months ago

I thought TTL caching was for expiring data, not syncing it?

Shawn 11 months ago

No way, lazy loading won't keep the cache updated like B does.

Lashandra 11 months ago

Wait, isn't lazy loading also a valid option?

Gilma 11 months ago

Totally agree, write-through caching is the way to go!

Mary 12 months ago

B is the best choice for keeping cache in sync with the database.

Nikita 12 months ago

I vaguely recall something about TTL caching, but I don't think it guarantees that the cache always matches the database.

Susana 1 year ago

I practiced a similar question, and I think the write-through caching strategy is the best option here since it updates the cache on write operations.

Lore 1 year ago

I'm not entirely sure, but I feel like lazy loading might not update the cache immediately when data changes.

Zana 1 year ago

I remember studying caching strategies, and I think the write-through strategy keeps the cache in sync with the database.

Gracia 1 year ago

I'm feeling pretty confident about this one. The write-through caching strategy is the obvious choice here, as it ensures that the cache and database are always in sync.

Marisha 1 year ago

Okay, I think I've got this. The key requirement is that the data in the cache must always match the data in the database. That means we need a write-through caching strategy, where updates to the database are immediately reflected in the cache.

Brianne 1 year ago

Hmm, I'm a bit confused by the options. I'll need to review my notes on the different caching strategies to understand the differences between them and figure out which one is the best fit.

Delsie 1 year ago

This looks like a tricky question. I'll need to think through the different caching strategies carefully to determine which one best meets the requirements.

Sage 1 year ago

Hmm, I'm a bit unsure about this one. The requirements mention natural language search, so Power Virtual Agents seems like a good option. But I'm not sure about the other part - does Business Process Flow really fit the customer service agent contact need? I might need to double-check the details on that one.

Selma 1 year ago

Based on my understanding, I believe statement III. is the correct one. Audits typically result in observations, recommendations, and a pass/fail assessment, which aligns with the description provided.

Yuonne 1 year ago

I think "generate short-term wins" could be one of the answers too, since R didn't keep the motivation going after the initial successes.

Cecil 1 year ago

Hmm, write-through sounds like the way to go. It's like having a personal assistant who updates your calendar as soon as you make a change. Keeps everything in sync!

Olive 1 year ago

↳ replying to Cecil

Write-through caching will ensure that the cache is always up-to-date with the database, maintaining data integrity.

Viva 1 year ago

↳ replying to Cecil

It's like having a real-time sync between the database and cache, ensuring data accuracy.

Tuyet 1 year ago

↳ replying to Cecil

Yeah, with write-through caching, the data is always consistent between the database and cache.

Frank 1 year ago

↳ replying to Cecil

Write-through caching is definitely the way to go for this scenario.

Myra 1 year ago

Lazy loading? That sounds like it might work, but wouldn't it mean the first cusMyraer to request the data would have to wait for it to be loaded from the database? Not very efficient.

Shaunna 1 year ago

↳ replying to Myra

Lazy loading is not the best option in this case. It would indeed make the first customer wait for data to be loaded from the database.

Nilsa 1 year ago

↳ replying to Myra

Write-behind caching could also work. It allows data to be written to the cache first and then asynchronously written to the database.

Luke 1 year ago

↳ replying to Myra

Use write-through caching. This strategy ensures that data is written to both the cache and the database at the same time.

Gwen 1 year ago

AWS AppConfig? I don't think that's the right tool for the job. This is more of a caching problem than a configuration management issue.

Shonda 1 year ago

↳ replying to Gwen

You're right, AWS AppConfig is not the right tool for this. ElastiCache with write-through caching is the way to go.

Milly 1 year ago

↳ replying to Gwen

Set up ElastiCache to use write-through caching to automatically update the cache when data is added or updated in the database.

German 1 year ago

↳ replying to Gwen

Use Amazon ElastiCache with the Memcached engine to store and retrieve data from the cache layer.

Troy 1 year ago

I'm not sure about the adding TTL caching strategy. Wouldn't that just cause the cache to expire after a certain time, regardless of database changes?

Shaniqua 1 year ago

↳ replying to Troy

User 3: Write-through caching ensures that the data in the cache always matches the data in the database.

Amina 1 year ago

↳ replying to Troy

User 2: That's a good idea. With write-through caching, data is written to the cache and the database at the same time.

Kirk 1 year ago

↳ replying to Troy

It's a more reliable option compared to TTL caching strategy.

Lelia 1 year ago

↳ replying to Troy

This ensures that the data in the cache always matches the data in the database.

Elfrieda 1 year ago

↳ replying to Troy

That way, data is written to the cache whenever it is written to the database.

Josefa 1 year ago

↳ replying to Troy

User 1: Have you considered using Amazon ElastiCache with write-through caching strategy?

Tammara 1 year ago

↳ replying to Troy

Use Amazon ElastiCache with write-through caching strategy.

Alethea 2 years ago

The write-through caching strategy seems like the obvious choice here. It ensures that the cache and database stay in sync, which is exactly what the company wants.

Sabina 1 year ago

↳ replying to Alethea

Agreed, it will make sure the cache and database are always in sync.

Lisandra 1 year ago

↳ replying to Alethea

We should definitely go with the write-through caching strategy.

Catherin 2 years ago

I'm not sure about that. Maybe we should consider the other options as well before making a decision.

Kenneth 2 years ago

I agree with Jackie. With write-through caching, data is always synchronized between the cache and the database.

Jackie 2 years ago

I think the answer is B) Implement the write-through caching strategy.

Amazon SAA-C03 Exam - Topic 2 Question 42 Discussion