Cloud CDN integration in GCP - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is Cloud CDN in Google Cloud Platform?

Cloud CDN (Content Delivery Network) is a service that caches content at locations close to users worldwide to reduce latency and improve load times.

beginner

How does Cloud CDN improve website performance?

By caching static and dynamic content at edge locations near users, Cloud CDN reduces the distance data travels, lowering latency and speeding up content delivery.

intermediate

What is the role of a backend service in Cloud CDN integration?

The backend service connects Cloud CDN to your origin servers (like Compute Engine or Cloud Storage), serving content that is not cached or refreshing cached content.

intermediate

Which HTTP headers are important for controlling Cloud CDN caching behavior?

Headers like Cache-Control, Expires, and Vary help Cloud CDN decide how long to cache content and when to revalidate it with the origin.

advanced

What is a cache key in Cloud CDN and why is it important?

A cache key defines how Cloud CDN identifies unique content to cache. It usually includes the URL, query parameters, and headers. Proper cache keys ensure correct content delivery and cache efficiency.

What is the primary benefit of using Cloud CDN?

A Reducing latency by caching content near users

B Increasing server CPU power

C Encrypting data at rest

D Managing user authentication

Cloud CDN reduces latency by caching content at edge locations close to users.

Which Google Cloud service acts as the origin for Cloud CDN content?

A BigQuery

B Cloud Pub/Sub

C Cloud Storage or Compute Engine backend services

D Cloud Functions

Cloud Storage buckets or Compute Engine instances serve as origin backends for Cloud CDN.

Which HTTP header controls how long Cloud CDN caches content?

A Cache-Control

B Authorization

C Content-Type

D User-Agent

Cache-Control header specifies caching policies for Cloud CDN.

What happens if Cloud CDN does not find content in its cache?

A It redirects to another CDN

B It fetches content from the origin backend

C It returns an error to the user

D It serves stale content

Cloud CDN fetches content from the origin backend when cache misses occur.

Which of these is NOT a factor in Cloud CDN cache key by default?

A URL path

B HTTP headers

C Query parameters

D Request body

Request body is not part of the cache key; cache keys use URL, query parameters, and headers.

Explain how Cloud CDN integrates with backend services in GCP to deliver content efficiently.

Think about how content flows from origin to user through Cloud CDN.

Describe the importance of cache keys in Cloud CDN and how they affect content delivery.

Consider how Cloud CDN decides what content to store and serve.

Practice

1. What is the primary purpose of Google Cloud CDN in a web application architecture?

easy

A. To cache content closer to users for faster delivery

B. To store user data securely in the cloud

C. To manage database connections efficiently

D. To provide virtual machines for computation

Solution

1. Step 1: Understand Cloud CDN's role

   Cloud CDN caches static and dynamic content at edge locations near users to reduce latency.

2. Step 2: Compare with other options

   Options A, B, and D describe other cloud services unrelated to CDN's caching function.

3. Final Answer:

   To cache content closer to users for faster delivery -> Option A

4. Quick Check:

   Cloud CDN = caching content near users [OK]

Hint: Cloud CDN speeds up content by caching near users [OK]

Common Mistakes:

• Confusing CDN with storage or compute services
• Thinking CDN manages databases
• Assuming CDN is for security only

2. Which GCP component must be configured to enable Cloud CDN for a backend service?

easy

A. Create a Cloud Storage bucket

B. Set up a Cloud SQL instance

C. Enable CDN on the backend service

D. Configure a Pub/Sub topic

Solution

1. Step 1: Identify CDN enabling step

   Cloud CDN is enabled by turning on the CDN option on the backend service linked to the load balancer.

2. Step 2: Eliminate unrelated components

   Cloud Storage buckets, Cloud SQL, and Pub/Sub are unrelated to enabling CDN on backend services.

3. Final Answer:

   Enable CDN on the backend service -> Option C

4. Quick Check:

   Enable CDN = backend service setting [OK]

Hint: Enable CDN directly on backend service in GCP [OK]

Common Mistakes:

• Trying to enable CDN on storage buckets only
• Confusing CDN with database or messaging setup
• Missing the backend service step

3. Given this simplified request flow for Cloud CDN: User -> HTTP(S) Load Balancer -> Backend Service (CDN enabled) -> Origin Server. What happens when a user requests a cached object that is still valid in the CDN cache?

medium

A. The load balancer fetches the object from the origin server

B. The CDN serves the cached object directly to the user

C. The backend service disables caching for that request

D. The request is redirected to another region

Solution

1. Step 1: Understand CDN cache hit behavior

   If the requested object is cached and valid, Cloud CDN serves it directly from the cache without contacting the origin.

2. Step 2: Analyze other options

   The load balancer fetches the object from the origin server is incorrect because the origin is bypassed on cache hit; options B and C do not describe CDN cache behavior.

3. Final Answer:

   The CDN serves the cached object directly to the user -> Option B

4. Quick Check:

   Cache hit = CDN serves cached content [OK]

Hint: Cache hit means CDN serves content, no origin call [OK]

Common Mistakes:

• Assuming origin is always contacted
• Confusing backend service disabling cache
• Thinking request redirects on cache hit

4. You configured Cloud CDN but notice that content is not being cached. Which of the following is the most likely misconfiguration?

medium

A. CDN is not enabled on the backend service

B. The load balancer is using HTTP instead of HTTPS

C. The origin server is unreachable

D. The forwarding rule is missing a static IP

Solution

1. Step 1: Check CDN enablement

   Cloud CDN must be explicitly enabled on the backend service to cache content.

2. Step 2: Evaluate other options

   Using HTTP vs HTTPS or missing static IP does not prevent caching; origin unreachable causes errors but not silent no-cache.

3. Final Answer:

   CDN is not enabled on the backend service -> Option A

4. Quick Check:

   CDN enabled on backend = caching works [OK]

Hint: Always enable CDN on backend service to cache content [OK]

Common Mistakes:

• Assuming HTTPS is required for caching
• Thinking static IP affects caching
• Ignoring backend service CDN setting

5. You want to design a scalable web app using Cloud CDN to serve static assets from a Cloud Storage bucket. Which setup correctly integrates Cloud CDN for this use case?

hard

A. Configure a forwarding rule to Cloud Storage and enable CDN there

B. Directly enable CDN on the Cloud Storage bucket without a load balancer

C. Use Cloud SQL as backend and enable CDN on it

D. Create a backend bucket pointing to Cloud Storage, enable CDN on it, then configure an HTTP(S) load balancer with this backend bucket

Solution

1. Step 1: Understand Cloud CDN integration with storage

   Cloud CDN integrates with Cloud Storage via a backend bucket configured in an HTTP(S) load balancer.

2. Step 2: Evaluate options

   Directly enable CDN on the Cloud Storage bucket without a load balancer is invalid because CDN cannot be enabled directly on storage buckets; C and D misuse services or configurations.

3. Final Answer:

   Create a backend bucket pointing to Cloud Storage, enable CDN on it, then configure an HTTP(S) load balancer with this backend bucket -> Option D

4. Quick Check:

   Backend bucket + load balancer + CDN = correct setup [OK]

Hint: Use backend bucket with load balancer to enable CDN on storage [OK]

Common Mistakes:

• Trying to enable CDN directly on storage buckets
• Using databases as backend for CDN
• Misconfiguring forwarding rules without load balancer