AI-200 practice: Implement Azure Managed Redis data operations, including caching, expiration, and invalidation

Question 1

An Azure Managed Redis cache stores a mix of session data with explicit TTLs and frequently recomputed AI response fragments with no TTL set. Memory usage is approaching capacity, and the team wants Redis to evict least-recently-used keys, but only from the subset of keys that actually have a TTL, leaving keys without a TTL untouched even under memory pressure.

Which eviction policy should you configure?

Accepted Answer

volatile-lru, which evicts the least recently used key only among keys that have a TTL set, leaving keys without a TTL intact under pressure

Answer

noeviction, which refuses new writes with an error when memory is full and never removes existing keys under pressure

Answer

allkeys-lru, which evicts the least recently used key among all keys in the dataset, including keys without a TTL

Answer

allkeys-random, which deletes a randomly selected key from the entire keyspace whenever Redis needs memory for a write

Question 2

Which Azure service provides an in-memory data store commonly used to cache frequent AI application queries and reduce latency?

Accepted Answer

Azure Managed Redis cache

Answer

Azure Data Lake Storage Gen2

Answer

Azure Database for PostgreSQL

Answer

Azure Files network shares

Question 3

You want cached AI-generated responses in Azure Managed Redis to automatically expire after 15 minutes so stale answers aren't served. What should you configure?

Accepted Answer

TTL of 900 seconds via EXPIRE or SETEX

Answer

Keyspace notification with no expiration

Answer

Cron job scanning and deleting every 15m

Answer

RDB snapshots scheduled every 15 minutes

Question 4

An application caches user session state in Azure Managed Redis and needs to invalidate a specific cached entry immediately when the underlying source record changes. What is the correct approach?

Accepted Answer

DEL or UNLINK the key when source updates

Answer

Wait for a multi-hour TTL to expire alone

Answer

Restart Redis to clear every cache entry

Answer

Rely on LRU eviction under memory pressure

Question 5

In Azure Managed Redis, you want to ensure that if a specific key (e.g., an AI model prompt cache) is not accessed for 30 minutes, it is automatically removed. Which Redis capability should you use?

Accepted Answer

Per-key TTL expiration

Answer

noeviction maxmemory

Answer

Active defragmentation

Answer

Client-side key rotate

Question 6

You add a cache-aside layer in Azure Managed Redis in front of an expensive LLM summarization call. Summaries should be reused for 10 minutes. Which flow is correct?

Accepted Answer

GET the key; on a miss, call the LLM, then SET key value EX 600 and return the value

Answer

Call the LLM on every request, then SET the result so other services can read it

Answer

SET every possible key with PERSIST at startup and never call the LLM again

Answer

GET the key; on a miss, return an empty result and let a nightly job fill the cache

Question 7

A trending-topics summary is cached in Redis with a 5-minute TTL. Each time it expires, hundreds of concurrent requests miss at once and each calls Azure OpenAI, which causes 429 throttling. What is the best mitigation?

Accepted Answer

On a miss, let only one caller rebuild the value (for example with a SET lock NX PX lock) while others briefly wait or serve the previous value, and add jitter to TTLs

Answer

Remove the TTL so the key never expires

Answer

Use FLUSHALL every 5 minutes so all keys refresh together

Answer

Increase the Redis cache size so that more keys fit in memory

Question 8

A RAG service caches generated answers in Redis. Each answer depends on several source documents. When a source document is updated, every cached answer built from it must be invalidated right away. No other keys should be affected and the production cache must not be blocked. What should you implement?

Accepted Answer

When you cache an answer, add its key to a per-document set (SADD doc:{id}:answers <key>); on update, read that set and DEL or UNLINK its members

Answer

Run KEYS answer:* on each update and delete the keys that match

Answer

Run FLUSHDB whenever any document changes

Answer

Rely on volatile-lru eviction to remove stale answers

Question 9

Your app moves from Azure Cache for Redis to Azure Managed Redis. Which connection settings does a redis-py client typically need for an Azure Managed Redis instance?

Accepted Answer

host=..redis.azure.net, port=10000, ssl=True

Answer

host=<name>.redis.cache.windows.net, port=6379, ssl=False

Answer

host=<name>.redis.cache.windows.net, port=6380, ssl=True

Answer

host=<name>.documents.azure.com, port=443, ssl=True

Question 10

Starting from a key `k` that doesn't exist, which two command sequences leave `k` holding value `v` and set to expire in 900 seconds? Select two.

Accepted Answer

SET k v EX 900

Accepted Answer

SETEX k 900 v

Answer

SET k v, then TTL k 900

Answer

SET k v, then PERSIST k

Answer

SET k v KEEPTTL

11 questions