DP-900 Describe considerations for working with non-relational data on Azure Practice Test 7 — 15 Questions

Question 1

A global gaming company stores player profiles in Azure Cosmos DB. Each profile document contains PlayerID (unique), PlayerName, Email, and a nested array of Achievements. The most common query is to look up a player by PlayerID and retrieve their achievements. The company needs strong consistency for reads and writes to ensure that when a player earns an achievement, it is immediately visible. Which partition key and consistency level should they choose?

Accepted Answer

B. Partition key: PlayerID; Consistency: Strong. Option B is correct because PlayerID is the natural partition key for the most common query (lookup by PlayerID), ensuring efficient single-partition queries. Strong consistency is required to guarantee that when a player earns an achievement, the write is immediately visible to all subsequent reads, which is critical for the gaming scenario.

Answer

A. Partition key: PlayerID; Consistency: Eventual

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C. Partition key: Achievements; Consistency: Strong

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D. Partition key: Email; Consistency: Bounded staleness

Question 2

A gaming company stores player scores in Azure Cosmos DB using the NoSQL API. Each document contains fields: PlayerID (unique to the player), GameID, Score, Timestamp. The most common query is: 'Retrieve all scores for a specific GameID, ordered by Score descending.' Which property should be chosen as the partition key to minimize Request Unit (RU) consumption?

Accepted Answer

GameID. GameID is the correct partition key because the most common query filters on GameID, and Cosmos DB routes queries to the exact physical partition(s) containing that GameID's data. This minimizes RU consumption by avoiding cross-partition fan-out, as the query engine can target a single partition. Using any other field would force scanning multiple partitions, increasing RU cost.

Answer

PlayerID

Answer

Score

Answer

Timestamp

Question 3

A company stores user-submitted profile photos. Each photo is accessed frequently for the first month after upload, then accessed rarely for the next year. After one year, the photos are deleted. Which Azure Blob Storage access tier should be used for the first month to minimize cost while ensuring low-latency access?

Accepted Answer

Hot tier. The Hot tier is correct because it provides low-latency access and is optimized for frequent read/write operations, which matches the requirement of frequent access during the first month. It minimizes cost compared to Premium (which is for high-throughput scenarios) while still offering the necessary performance for user-submitted profile photos.

Answer

Cool tier

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Archive tier

Answer

Premium tier

Question 4

A travel booking application stores user itineraries in Azure Cosmos DB using the NoSQL API. Each itinerary document contains: UserID (unique to user), ItineraryID, Destination, BookingDate, and a nested array of Activities. The most common query is: 'Retrieve all itineraries for a specific UserID sorted by BookingDate descending.' To minimize Request Unit (RU) consumption, which partition key should be chosen?

Accepted Answer

UserID. UserID is the correct partition key because the most common query filters on UserID, ensuring that all itineraries for a specific user are stored in the same physical partition. This allows the query to target a single partition, minimizing cross-partition queries and reducing Request Unit (RU) consumption. A partition key that aligns with the primary query filter is essential for optimal performance and cost efficiency in Azure Cosmos DB.

Answer

ItineraryID

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Destination

Answer

BookingDate

Question 5

A social media application stores user profiles in Azure Cosmos DB using the NoSQL API. Each profile includes UserID, Name, Email, and an array of Posts. The most common query retrieves a user's profile by UserID. The application requires strong consistency for writes so that once a profile is updated, all subsequent reads see the latest data. To minimize Request Unit (RU) consumption, which partition key should be chosen?

Accepted Answer

UserID. UserID is the correct partition key because it is the primary filter in the most common query (retrieving a profile by UserID), ensuring each query targets a single logical partition. This minimizes cross-partition queries and RU consumption. Additionally, UserID provides high cardinality and even distribution, which prevents hot partitions and supports the required strong consistency for writes.

Answer

Email

Answer

Name

Answer

A synthetic partition key combining UserID and Region

Question 6

A media company stores user profile images in Azure Blob Storage. Regulators require that the images cannot be deleted or overwritten for a period of 90 days after upload. Which Azure Blob Storage feature should the company enable to meet this requirement?

Accepted Answer

B: Immutable storage with a time-based retention policy. Immutable storage with a time-based retention policy (also known as WORM – Write Once, Read Many) prevents blobs from being deleted or overwritten for a specified retention interval. By setting a 90-day policy, the company ensures that user profile images remain unmodifiable and undeletable during that period, directly satisfying the regulatory requirement.

Answer

A: Soft delete

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C: Access tiers (Hot, Cool, Archive)

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D: Lifecycle management rules

Question 7

A travel booking application stores booking data in Azure Cosmos DB using the NoSQL API. Each booking document contains: BookingID (unique), UserID, Destination, TravelDate, Price. The most common query is: 'Retrieve all bookings for a specific UserID, sorted by TravelDate descending.' To minimize Request Unit (RU) consumption, which property should be chosen as the partition key?

Accepted Answer

UserID. UserID is the correct partition key because the most common query filters on UserID, and Cosmos DB routes queries to the exact physical partition(s) containing that UserID's data. This minimizes cross-partition fan-out, reducing RU consumption. A partition key should align with the primary query filter to enable efficient point-read or single-partition query execution.

Answer

BookingID

Answer

Destination

Answer

TravelDate

Question 8

A company stores IoT temperature readings in Azure Cosmos DB using the NoSQL API. Each document contains: DeviceID, Timestamp, Temperature, Location. Data is ingested at a rate of 10,000 documents per second from thousands of devices. The most common query is 'Get all readings for a specific DeviceID in the last hour.' Which partition key should be chosen to avoid hot partitions while still supporting the query efficiently?

Accepted Answer

A synthetic key combining DeviceID and Timestamp (e.g., DeviceID_yyyy-MM-dd-HH). Option D is correct because a synthetic key combining DeviceID and Timestamp (e.g., DeviceID_yyyy-MM-dd-HH) ensures that data for a specific device is distributed across multiple physical partitions based on the hour, preventing a single partition from becoming a hot spot. This design still supports the most common query efficiently by allowing Cosmos DB to route the query to only the partitions containing the relevant hour's data, using the partition key in the WHERE clause.

Answer

DeviceID

Answer

Timestamp (e.g., per minute)

Answer

Location

Question 9

A media company stores high-definition video files for on-demand streaming. The files are accessed very frequently for the first 30 days after upload, then rarely (about once per month) for the next year, and after one year they are rarely accessed but must be retained for compliance (about once per year). Which set of access tier transitions minimizes cost while meeting access requirements?

Accepted Answer

Hot for 30 days, then Cool for 11 months, then Archive. Option A is correct because it aligns the Azure Blob Storage access tier transitions with the access pattern: Hot tier for the first 30 days of frequent access, Cool tier for the next 11 months of monthly access, and Archive tier after one year for rare compliance access. This minimizes cost by moving data to progressively cheaper storage tiers as access frequency drops, while still meeting the access requirements (Cool supports monthly access, Archive supports yearly access with retrieval time).

Answer

Hot for 30 days, then Archive immediately

Answer

Cool for 30 days, then Cool for 11 months, then Archive

Answer

Hot for 365 days, then Archive

Question 10

A company stores JSON documents for a product catalog. Each document has a flexible schema because different product categories have different attributes. The catalog is read-heavy and requires low-latency lookups by product ID. The company expects to handle millions of products and needs to serve customers globally with low latency. Which Azure NoSQL data store should they choose?

Accepted Answer

Azure Cosmos DB. Azure Cosmos DB is the correct choice because it is a globally distributed, multi-model NoSQL database that natively supports JSON documents with flexible schemas, provides single-digit-millisecond latency for read-heavy workloads via automatic indexing, and offers turnkey global distribution across Azure regions to serve customers worldwide with low latency.

Answer

Azure Table Storage

Answer

Azure Blob Storage

Answer

Azure SQL Database

Question 11

A company stores historical sales data in Azure Blob Storage. The data is accessed about once per month and must be immediately available for read when needed. The company wants to minimize storage cost while meeting the access requirement. Which access tier should they use?

Accepted Answer

Cool tier. The Cool tier is optimal because the data is accessed only once per month, but must be immediately available for reads. Cool tier offers lower storage cost than Hot tier while maintaining low-latency access (no retrieval delay), meeting the requirement at minimal cost.

Answer

Hot tier

Answer

Cold tier

Answer

Archive tier

Question 12

A gaming application requires a high-performance leaderboard that stores player scores and retrieves the top 10 scores quickly. The data does not require complex queries or a fixed schema. The leaderboard must support updates as new scores are submitted. Which Azure data store is most appropriate for this scenario?

Accepted Answer

Azure Cache for Redis. Azure Cache for Redis is the most appropriate choice because it provides an in-memory data structure store with native support for sorted sets (via the ZADD and ZRANGE commands), which are ideal for maintaining a real-time leaderboard. It can handle high-throughput score updates and retrieve the top 10 scores in O(log(N)) time, meeting the low-latency and performance requirements without needing a fixed schema.

Answer

Azure Cosmos DB with SQL API

Answer

Azure Table storage

Answer

Azure Blob Storage

Question 13

A social media application stores user posts in Azure Cosmos DB using the NoSQL API. Each document includes: PostID (unique), UserID, Timestamp, Content. The most common query is: 'Get all posts for a specific UserID, sorted by Timestamp descending.' Which partition key should be chosen to distribute load evenly across physical partitions while also supporting this query efficiently?

Accepted Answer

UserID. UserID is the correct partition key because it evenly distributes write operations across physical partitions (each user has a unique ID) and directly supports the most common query: filtering by UserID. With UserID as the partition key, the query 'Get all posts for a specific UserID, sorted by Timestamp descending' becomes a single-partition query (using the partition key in the WHERE clause), which is efficient and avoids cross-partition fan-out. This design also allows Cosmos DB to use the Timestamp field as a sort key within each logical partition, enabling efficient sorting without additional indexing overhead.

Answer

PostID

Answer

Timestamp

Answer

Content

Question 14

A company develops an IoT device registry that stores device metadata as JSON documents. Each device has a unique DeviceID, and the attributes vary per device type (e.g., sensors, actuators). The application requires low-latency reads by DeviceID and needs global distribution to support devices worldwide. The team wants to use a fully managed NoSQL database in Azure. Which API should they choose for Azure Cosmos DB?

Accepted Answer

SQL API. The SQL API (formerly DocumentDB API) is the native API for Azure Cosmos DB, providing full support for querying JSON documents with a SQL-like syntax. It offers the lowest latency reads by ID (point reads) and native global distribution, making it ideal for a device registry where each device has a unique DeviceID and variable attributes. The SQL API also supports indexing all properties automatically, which is critical for the varied device types.

Answer

MongoDB API

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Cassandra API

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Table API

Question 15

A company must archive customer correspondence PDFs that are rarely accessed but must be retained for seven years. The documents must be available for read within seconds if requested. Which Azure Blob Storage access tier should be used to minimize storage cost while meeting the availability requirement?

Accepted Answer

Cool. The Cool tier is optimal because it balances low storage cost with high availability for data that is infrequently accessed but must be retrievable within seconds. It offers the same low-latency retrieval as the Hot tier (milliseconds) but at a lower storage price, making it ideal for archived correspondence that still requires immediate read access.

Answer

Hot

Answer