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In cloud architecture, performance is key. Caching is a powerful technique to reduce latency, decrease the load on your backend servers, and improve the overall user experience. Module 12 of the AWS Academy Cloud Architecting curriculum focuses on how to implement effective caching strategies using services like Amazon CloudFront and Amazon ElastiCache.

Here is your comprehensive guide to the Module 12 Knowledge Check, including all questions, options, and the reasoning behind each answer.

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1. Understanding Caching

Question: What is caching?

• Options:
  • A global network for content distribution
  • A way to store passwords
  • An in-memory database
  • A high-speed data storage layer
• Correct Answer: A high-speed data storage layer
• Why: A cache is a high-speed data storage layer used to store frequently accessed data so that future requests for that data are served faster than is possible by accessing the data’s primary storage location.

2. Identifying Cacheable Data

Question: Which type of data should you cache?

• Options:
  • Data that can be retrieved quickly with simple queries
  • Specialized data that is needed by a subset of users
  • Dynamically generated web content
  • Static data that is frequently accessed
• Correct Answer: Static data that is frequently accessed
• Why: Good candidates for caching include data that does not change often (static) and data that users access frequently, as this provides the most significant performance gains.

3. Benefits of Caching

Question: Which is a benefit of caching?

• Options:
  • Increased application reliability
  • Decreased costs
  • Load balancing the application
  • Reduced response latency
• Correct Answer: Reduced response latency
• Why: Caching reduces response latency by eliminating slow resources or high-latency network hops between the requester and the content origin.

4. Edge Caching Content Types

Question: Which types of content on a web page can be cached using an edge cache? (Select TWO.)

• Options:
  • Video files, such as a product demo
  • Web objects, such as hyperlinks
  • User-generated data, such as search terms entered by user
  • Shopping cart filled with a user’s item
  • Dynamically generated content, such as a user’s name
• Correct Answers: 1. Video files, such as a product demo2. Web objects, such as hyperlinks
• Why: An edge cache is designed to store static content. This includes web objects (like HTML, CSS, or JavaScript files), image files, and video files.

5. Features of Amazon CloudFront

Question: What does Amazon CloudFront enable?

• Options:
  • Transactional processing with an in-memory database
  • Automatic creation of a time to live (TTL) value
  • Bidirectional caching between users and an origin host
  • Multi-tiered and regional caching of content
• Correct Answer: Multi-tiered and regional caching of content
• Why: CloudFront provides a multi-tiered cache that allows for various expiration rules (TTL) and offers regional caching to reduce the number of network hops required to reach content.

6. Edge Locations and Latency

Question: How does Amazon CloudFront use edge locations?

• Options:
  • It caches all content from an origin distribution at the edge location and delivers the content to clients through the fastest edge location.
  • It caches frequently accessed content at edge locations. It delivers the cached content to clients through the edge location with the lowest latency to those clients.
  • It caches local content at edge locations. It delivers the cached content to clients through the edge location that requires the fewest network hops to reach those clients.
  • It caches Regional data at Regional edge locations and delivers the content to clients through their Regional edge location.
• Correct Answer: It caches frequently accessed content at edge locations. It delivers the cached content to clients through the edge location with the lowest latency to those clients.
• Why: If requested content is unavailable at an edge location, CloudFront fetches it from the origin and caches it. It then serves future requests from the edge location that provides the lowest latency to the end user.

7. Efficient Video Delivery

Question: Which statement describes an efficient way to deliver on-demand video content?

• Options:
  • Launch an Amazon EC2 instance to host your video content. Then use Amazon CloudFront to deliver the content.
  • Use Amazon S3 to store the content. Then use Amazon CloudFront to deliver the content.
  • Launch an Amazon EC2 instance to host and serve your video content.
  • Use Amazon S3 to store and serve the content.
• Correct Answer: Use Amazon S3 to store the content. Then use Amazon CloudFront to deliver the content.
• Why: Storing large video files in S3 and using CloudFront to cache and deliver them from edge locations near users is the most efficient and scalable way to handle on-demand video.

8. DDoS Protection

Question: Which role does Amazon CloudFront play in protecting against distributed denial of service (DDoS) attacks?

• Options:
  • Performs deep packet inspection to detect attacks
  • Routes traffic through edge locations
  • Controls traffic by the source IP addresses of requests
  • Restricts traffic by geography to help block attacks that originate from specific countries
• Correct Answer: Routes traffic through edge locations
• Why: CloudFront routes traffic through a massive global network of edge locations, which helps disperse and absorb the high load of a DDoS attack, reducing the impact on the origin server.

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Summary Checklist

Caching Concept	Best AWS Service/Feature
Global Content Delivery	Amazon CloudFront
High-Speed In-Memory Caching	Amazon ElastiCache
Static Content Storage	Amazon S3
Reduced Latency Locations	Edge Locations

For more details, visit the original video guide: YouTube Link