DA0-002 Practice Exam 1 — 20 Questions

Question 1

Refer to the exhibit. A data architect is designing a data dictionary for a relational database. Based on the exhibit, which data concept is being illustrated?

Accepted Answer

Data constraints. The exhibit shows a table definition with column attributes such as NOT NULL, UNIQUE, and PRIMARY KEY, which are data constraints that enforce rules on the data values. Data constraints ensure data integrity by restricting what data can be stored in a column, such as preventing null values or duplicate entries. This directly aligns with the concept of data constraints, making option A correct.

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Data aggregation

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Data normalization

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Data cardinality

Question 2

Which TWO of the following are true about correlation and causation? (Select TWO).

Accepted Answer

Correlation does not imply causation. Correlation measures the strength and direction of a linear relationship between two variables, but it does not imply that one variable causes the other. Causation requires controlled experiments with randomization to rule out confounding variables and establish a cause-effect relationship.

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Correlation measures both linear and nonlinear relationships

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Causation can always be inferred from a controlled experiment without randomization

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If two variables are highly correlated, one must cause the other

Question 3

A business analyst is asked to distinguish between KPIs and metrics for a new dashboard. According to CompTIA Data+, which TWO statements correctly differentiate KPIs from metrics? (Choose two.)

Accepted Answer

KPIs are directly tied to strategic business objectives. KPIs are tied to strategic objectives and are often leading or lagging indicators. Metrics are operational measurements that may support KPIs but are not necessarily strategic.

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KPIs and metrics are interchangeable terms

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Metrics are always more important than KPIs

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KPIs are always lagging indicators

Question 4

Which database concept ensures that data in one table corresponds to data in another table, preventing orphan records?

Accepted Answer

Referential integrity. Referential integrity ensures that foreign key values match primary key values in the referenced table.

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Index

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Foreign key

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Primary key

Question 5

A data engineer is designing a system to store raw sensor data from thousands of IoT devices. The data will be used later for various analytics projects, but the schema is not yet defined. Which storage solution is most appropriate?

Accepted Answer

Data lake. A data lake stores raw data in its native format (e.g., S3, ADLS) without requiring a predefined schema, making it suitable for IoT data.

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Data mart

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Data warehouse

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Relational database

Question 6

A data engineer is designing a data warehouse for a retail company. The fact table must record each sale transaction, including product ID, store ID, date, and quantity sold. The product details (name, category, price) are stored in a separate table. This design is an example of which data modeling concept?

Accepted Answer

Star schema. This design is a classic star schema, where a central fact table (sales transactions) contains foreign keys to dimension tables (product, store, date). The fact table stores quantitative measures (quantity sold) and foreign keys, while dimension tables hold descriptive attributes (product name, category, price). This separation optimizes query performance for OLAP workloads by reducing joins and enabling straightforward aggregations.

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Data lake

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Normalization

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Snowflake schema

Question 7

A data analyst includes a map showing customer locations by zip code. The map reveals exact addresses for a few customers due to data granularity. This violates which principle?

Accepted Answer

Anonymization. The map reveals exact addresses for a few customers due to the granularity of zip code data. This directly violates the principle of anonymization, which requires that data be processed in such a way that individuals cannot be identified. By exposing precise locations, the data is no longer anonymized, as it allows re-identification of specific individuals.

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Informed consent

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Data minimization

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Data quality

Question 8

Refer to the exhibit. A data analyst is trying to extract data from a SQL Server database but receives the error. Which configuration change should the analyst recommend to the database administrator?

Accepted Answer

Enable Mixed Mode authentication on the SQL Server. The error indicates that the server is configured for Windows authentication only, but the login attempt used SQL authentication. Enabling Mixed Mode authentication allows both Windows and SQL authentication, resolving the issue.

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Change the server firewall to allow port 1433

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Use a different extraction tool that supports Windows authentication

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Grant the 'dataminer' user SELECT permissions

Question 9

A business analyst needs to show the monthly sales trend for the past three years. Which chart type is most appropriate?

Accepted Answer

Line chart. Line charts are ideal for displaying trends over time, making them suitable for showing monthly sales trends.

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Histogram

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Pie chart

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Scatter plot

Question 10

A data analyst is using a public API to collect historical weather data. The API has a rate limit of 100 requests per minute, but the analyst needs to retrieve 10,000 records as quickly as possible. What strategy should be used?

Accepted Answer

Paginate with appropriate delays. Paginating with appropriate delays respects the API's rate limit of 100 requests per minute while maximizing throughput. By splitting the 10,000 records into pages (e.g., 100 records per page) and sending requests at a rate just under the limit (e.g., one request every 0.6 seconds), the analyst can retrieve all data in approximately 100 minutes without triggering HTTP 429 rate-limit errors.

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Increase the request rate

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Use multiple API keys

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Download a precompiled dataset

Question 11

A data analyst is tasked with collecting data from a web API that returns JSON. The API requires an API key in the header. Which method should be used to authenticate?

Accepted Answer

Add the API key in the HTTP header as 'Authorization: Bearer '. The correct method is to include the API key in the HTTP header using the 'Authorization: Bearer ' format. This is the standard approach for token-based authentication in REST APIs, as defined by RFC 6750. It keeps the credential out of URLs and logs, and is the expected mechanism for API key authentication in modern web APIs.

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Use a session cookie

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Store the API key in the database and reference it

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Include the API key in the URL query string

Question 12

A data scientist is preparing data for a K-means clustering algorithm. The dataset contains features measured in different units (e.g., income in dollars and age in years). Which preprocessing step is most critical before running K-means?

Accepted Answer

Standardize or normalize the features. K-means is sensitive to the scale of features because it uses Euclidean distance. Min-max normalization or standardization ensures all features contribute equally.

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Remove outliers

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Encode categorical variables

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Perform feature selection

Question 13

A data analyst is performing data profiling on a customer table. Which TWO of the following are key metrics to assess data quality? (Select TWO.)

Accepted Answer

Minimum and maximum values. Null counts indicate missing values, and min/max values can reveal outliers or unexpected ranges. Row count alone doesn't assess quality; cardinality and data type verification are also important but the question asks for key metrics among the options.

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Row count

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Cardinality

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Data type verification

Question 14

A retail company operates 50 stores across the country. The data analyst has been asked to create a dashboard to visualize monthly sales trends over the past two years and compare the performance of the top 5 stores. The dataset includes store name, date, and daily sales amount. Initial exploration reveals that some stores have missing sales data for certain months due to system outages, and there are occasional extreme values caused by promotional events (e.g., Black Friday sales are 10x normal). The analyst needs to choose an appropriate visualization approach that accurately represents the trends and comparisons while handling these data quality issues. What should the analyst do to best meet the requirements?

Accepted Answer

Use a line chart for the overall monthly sales trend (aggregated across all stores) and a separate bar chart for the top 5 stores by total sales, with tooltips explaining outlier values.. It combines a line chart for overall trend (aggregating all stores) and bar charts for top 5 stores, which allows comparison while handling missing data through aggregation. Tooltips can provide context for outliers. Option A is wrong because using separate line charts for each store becomes cluttered with 50 stores, and excluding outliers may omit valuable information about promotions. Option B is wrong because filtering out stores with missing data could remove important stores and distort the trend. Option D is wrong because a stacked bar chart with all 50 stores would be difficult to read and doesn't show trends over time effectively.

Answer

Use a line chart for each store's monthly sales and exclude outliers from the dataset.

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Use a bar chart showing monthly sales for each month and filter out stores with missing data.

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Use a stacked bar chart with all 50 stores, each bar representing a month.

Question 15

A large online retailer stores customer orders in a PostgreSQL database. Each order has a unique order ID, and the database is normalized to 3NF. Which type of data is this?

Accepted Answer

Structured data. The data is structured because it resides in a normalized PostgreSQL database with a unique order ID and conforms to a fixed schema (3NF). Structured data is organized into rows and columns with defined data types, enabling efficient SQL querying and ACID compliance. PostgreSQL's relational model enforces this structure through tables, constraints, and indexes.

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Semi-structured data

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Unstructured data

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Metadata

Question 16

A business analyst wants to show the relationship between advertising spend (independent variable) and sales revenue (dependent variable) for 12 different regions. Each region will be represented by a point. Which chart type is most appropriate?

Accepted Answer

Scatter plot. A scatter plot is the most appropriate chart type because it directly visualizes the relationship between two continuous variables—advertising spend (independent) and sales revenue (dependent)—by plotting each of the 12 regions as a point. This allows the analyst to assess correlation, trends, and outliers, which is the core purpose of scatter plots in data visualization.

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Line chart

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Bar chart

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Histogram

Question 17

An analyst is fitting a polynomial regression model and wants to choose the degree that minimizes overfitting. Which technique should the analyst use?

Accepted Answer

Ridge regression (L2). Ridge regression (L2) adds a penalty proportional to the square of the magnitude of coefficients, which shrinks them toward zero but does not eliminate them. This regularization reduces variance and helps prevent overfitting in polynomial regression by controlling the influence of higher-degree terms, making it the correct technique for minimizing overfitting while retaining all features.

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Lasso regression (L1)

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Principal component analysis (PCA)

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Stepwise selection

Question 18

An organization is implementing a data lake to store raw data from various sources. Which THREE characteristics are typically associated with a data lake compared to a data warehouse?

Accepted Answer

Supports batch and real-time processing. Data lakes are designed to ingest and process data in both batch and real-time streaming modes, unlike data warehouses which primarily handle batch ETL workloads. This flexibility is enabled by technologies like Apache Kafka for streaming and Apache Spark for batch processing, allowing the data lake to support diverse ingestion patterns without pre-schematization.

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Supports only structured data

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Requires data transformation before loading

Question 19

A company is merging two customer databases from different acquisitions. They need to identify duplicate records. Which data profiling technique is most effective?

Accepted Answer

Fuzzy matching on name and address. Fuzzy matching on name and address is the most effective technique because customer databases from different acquisitions often contain variations in spelling, formatting, and abbreviations (e.g., 'Bob' vs. 'Robert', 'St.' vs. 'Street'). Exact matching would miss these duplicates, while fuzzy matching uses algorithms like Levenshtein distance or Jaro-Winkler to quantify similarity and identify near-matches, ensuring comprehensive deduplication.

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Manually compare all records

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Exact match on customer names

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Use primary keys from each database

Question 20

A company needs to store data that is highly interconnected, such as social network relationships. Which two database types are best suited for this? (Select TWO.)

Accepted Answer

Document store (e.g., MongoDB). Graph databases excel at storing relationships, and NoSQL databases support flexible schemas for interconnected data.

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Relational database

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Wide-column store (e.g., Cassandra)

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Key-value store (e.g., Redis)