Azure Cache for Redis - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is Azure Cache for Redis?

Azure Cache for Redis is a managed service that provides a fast, in-memory data store based on the open-source Redis technology. It helps applications perform better by storing data in memory for quick access.

beginner

Why use Azure Cache for Redis instead of a traditional database for some data?

Because Redis stores data in memory, it can retrieve data much faster than traditional databases that read from disk. This makes it great for scenarios like session storage, leaderboards, and caching frequently accessed data.

intermediate

What are the main data structures supported by Azure Cache for Redis?

Azure Cache for Redis supports strings, hashes, lists, sets, sorted sets, bitmaps, and hyperloglogs. These allow flexible ways to store and manipulate data quickly.

intermediate

How does Azure Cache for Redis ensure high availability?

It uses replication and automatic failover. If the primary cache node fails, a replica takes over automatically to keep the cache available without interruption.

beginner

What is a common use case for Azure Cache for Redis in web applications?

A common use case is session state storage, where user session data is stored in Redis to allow fast retrieval and scalability across multiple web servers.

What type of storage does Azure Cache for Redis use to store data?

A Relational database

B Disk-based storage

C In-memory storage

D Cloud blob storage

Azure Cache for Redis stores data in memory, which allows very fast data access compared to disk-based storage.

Which of the following is NOT a data structure supported by Azure Cache for Redis?

A Sorted sets

B Lists

C Hashes

D Graphs

Azure Cache for Redis does not natively support graph data structures.

How does Azure Cache for Redis handle failover to maintain availability?

A Automatic failover to replica

B Switch to disk storage

C Manual restart by admin

D No failover support

Azure Cache for Redis automatically fails over to a replica node if the primary node fails.

Which scenario is best suited for using Azure Cache for Redis?

A Storing large files

B Caching frequently accessed data

C Long-term archival

D Running complex SQL queries

Azure Cache for Redis is ideal for caching data that needs fast access.

What is a benefit of using Azure Cache for Redis for session state in web apps?

A Centralized, fast access across servers

B Slower access to session data

C Requires no network

D Automatically encrypts all data

Using Redis for session state allows multiple web servers to access session data quickly and consistently.

Explain how Azure Cache for Redis improves application performance.

Think about how storing data in memory helps speed things up.

Describe the high availability features of Azure Cache for Redis.

Consider what happens if the main cache node stops working.

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