Azure Cache for Redis - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ service_behavior

intermediate

How does Azure Cache for Redis handle data persistence?

Azure Cache for Redis offers different persistence options. Which of the following best describes how data persistence works in Azure Cache for Redis?

A Persistence is disabled by default and can be enabled to save snapshots to Azure Storage at configured intervals.

B Data is automatically saved to disk every second without any configuration.

C Data is stored permanently in Azure Blob Storage and Redis only caches it temporarily.

D Azure Cache for Redis does not support any form of data persistence.

💡 Hint

Think about whether persistence is on by default or requires setup.

Azure Cache for Redis persistence is disabled by default. You can enable it to save snapshots of your cache data to Azure Storage at intervals you configure. This helps recover data after a restart.

❓ Architecture

intermediate

Choosing the right Azure Cache for Redis tier for high availability

You need a Redis cache that supports automatic failover and data replication across multiple nodes. Which Azure Cache for Redis tier should you choose?

A Free tier

B Standard tier

C Basic tier

D Premium tier

💡 Hint

Consider which tier supports clustering and geo-replication.

The Premium tier supports clustering, data replication, and automatic failover, making it suitable for high availability scenarios.

❓ security

advanced

Securing Azure Cache for Redis access

You want to restrict access to your Azure Cache for Redis instance so only your Azure App Service can connect. Which method provides the most secure and recommended way to achieve this?

A Use Azure Private Link to connect the App Service privately to the Redis cache.

B Use the Redis access keys and share them with the App Service.

C Enable firewall rules to allow only the App Service outbound IP addresses.

D Disable authentication on the Redis cache to simplify access.

💡 Hint

Think about private network connectivity versus just IP filtering.

Azure Private Link allows private, secure network connectivity between your App Service and Redis cache, avoiding exposure over the public internet.

❓ Configuration

advanced

Configuring Redis cache for geo-replication

You want to configure geo-replication between two Azure Cache for Redis instances in different regions. Which statement is true about this setup?

A Geo-replication is supported only in the Basic tier and requires manual synchronization.

B Geo-replication is not supported by Azure Cache for Redis.

C Geo-replication requires Premium tier caches and uses a primary-secondary replication model.

D Geo-replication is automatic in all tiers and requires no configuration.

💡 Hint

Check which tier supports geo-replication and how it works.

Geo-replication is a Premium tier feature that links a primary cache with one or more secondary caches in different regions for disaster recovery.

✅ Best Practice

expert

Optimizing Azure Cache for Redis for high throughput and low latency

You have a high-traffic web application using Azure Cache for Redis. Which combination of configurations will best optimize throughput and latency?

A Use Basic tier with a single node and enable persistence.

B Use Premium tier with clustering enabled and configure client-side connection pooling.

C Use Standard tier with multiple caches and disable SSL to reduce overhead.

D Use Premium tier without clustering and increase the cache size beyond needed.

💡 Hint

Think about clustering and client connection management.

Premium tier clustering allows sharding data across multiple nodes, improving throughput. Client-side connection pooling reduces connection overhead and latency.

Practice

1. What is the main purpose of Azure Cache for Redis?

easy

A. To permanently store large files

B. To host virtual machines

C. To replace Azure SQL Database

D. To store data in memory to speed up applications

Solution

1. Step 1: Understand Azure Cache for Redis function

   Azure Cache for Redis stores data in memory, which is much faster than disk storage.

2. Step 2: Identify the main benefit

   This in-memory storage helps speed up applications by reducing the time to access data.

3. Final Answer:

   To store data in memory to speed up applications -> Option D

4. Quick Check:

   In-memory cache = speed up apps [OK]

Hint: Remember: Redis cache is for fast memory storage [OK]

Common Mistakes:

• Thinking Redis stores large files permanently
• Confusing Redis with database replacement
• Assuming Redis hosts virtual machines

2. Which property sets the pricing tier when creating an Azure Cache for Redis instance?

easy

A. sku_name

B. resource_group

C. location

D. capacity

Solution

1. Step 1: Identify pricing tier property

   The pricing tier is controlled by the SKU name, which defines features and cost.

2. Step 2: Differentiate from other properties

   Capacity sets size, location sets region, resource group organizes resources.

3. Final Answer:

   sku_name -> Option A

4. Quick Check:

   Pricing tier = sku_name [OK]

Hint: Pricing tier is set by sku_name, not capacity [OK]

Common Mistakes:

• Confusing capacity with pricing tier
• Using location or resource group as pricing tier
• Mixing sku_name with capacity

3. Given this snippet to create Azure Cache for Redis in ARM template:

{
  "type": "Microsoft.Cache/Redis",
  "name": "myRedisCache",
  "apiVersion": "2023-04-01",
  "location": "eastus",
  "properties": {
    "sku": { "name": "Standard", "family": "C", "capacity": 2 },
    "enableNonSslPort": false
  }
}

What does setting enableNonSslPort to false do?

medium

A. Disables the non-SSL port, forcing SSL connections

B. Enables non-SSL port for faster connections

C. Sets the cache size to 2 GB

D. Changes the cache location to westus

Solution

1. Step 1: Understand enableNonSslPort property

   This property controls if clients can connect without SSL (non-secure).

2. Step 2: Interpret false value

   Setting it to false disables non-SSL port, so only secure SSL connections are allowed.

3. Final Answer:

   Disables the non-SSL port, forcing SSL connections -> Option A

4. Quick Check:

   enableNonSslPort false = SSL only [OK]

Hint: False disables non-SSL port, secure only [OK]

Common Mistakes:

• Thinking false enables non-SSL port
• Confusing capacity with enableNonSslPort
• Assuming location changes with this property

4. You try to create an Azure Cache for Redis with this JSON snippet:

{
  "type": "Microsoft.Cache/Redis",
  "name": "cache1",
  "apiVersion": "2023-04-01",
  "location": "eastus",
  "properties": {
    "sku": { "name": "Standard", "family": "C", "capacity": 0 },
    "enableNonSslPort": true
  }
}

What is the problem with this configuration?

medium

A. enableNonSslPort cannot be true for Basic SKU

B. Capacity cannot be zero; it must be at least 1

C. Location eastus is invalid

D. Missing resource group property

Solution

1. Step 1: Check capacity value

   Capacity defines cache size and must be a positive integer starting at 1.

2. Step 2: Validate other properties

   enableNonSslPort can be true, eastus is valid location, resource group is set outside this snippet.

3. Final Answer:

   Capacity cannot be zero; it must be at least 1 -> Option B

4. Quick Check:

   Capacity ≥ 1 required [OK]

Hint: Capacity must be 1 or more, zero is invalid [OK]

Common Mistakes:

• Assuming zero capacity is allowed
• Thinking enableNonSslPort is restricted by SKU
• Confusing location validity

5. You want to reduce database load by caching user session data using Azure Cache for Redis. Which combination of settings is best to ensure fast response and cost efficiency?

hard

A. Use Basic SKU with capacity 10 and enableNonSslPort false

B. Use Premium SKU with capacity 5 and enableNonSslPort true

C. Use Standard SKU with capacity 3 and enableNonSslPort false

D. Use Standard SKU with capacity 1 and enableNonSslPort false

Solution

1. Step 1: Balance performance and cost

   Standard SKU offers good performance at moderate cost; capacity 3 provides enough memory for sessions without overspending.

2. Step 2: Ensure secure connections

   Disabling non-SSL port (false) ensures secure data transfer, important for user sessions.

3. Step 3: Evaluate other options

   Basic SKU with high capacity is less performant; Premium SKU with high capacity is costly; enabling non-SSL port reduces security.

4. Final Answer:

   Use Standard SKU with capacity 3 and enableNonSslPort false -> Option C

5. Quick Check:

   Standard SKU + moderate capacity + secure port = best balance [OK]

Hint: Pick Standard SKU, moderate size, secure port for best balance [OK]

Common Mistakes:

• Choosing too large capacity increasing cost
• Using Basic SKU for heavy session caching
• Enabling non-SSL port reducing security