AT&T Interview Questions, Process, and Tips

Q1. Informatica - Difference between router and filter transformation
Ans. 
Router and filter transformations are used in Informatica for data filtering, but they have different functionalities.
• Router transformation is used to route data based on specified conditions to multiple output groups.

• Filter transformation is used to filter rows based on specified conditions and pass only the matching rows to the output.

• Router transformation can have multiple output groups, each with its own condition.

• ...read more
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Q2. Informatica - How can we handle duplicates in mappings
Ans. 
Duplicates in mappings can be handled using various techniques in Informatica.
• Use the Sorter transformation to sort the data and then use the Aggregator transformation to eliminate duplicates.

• Use the Expression transformation with the DISTINCT keyword to remove duplicates.

• Use the Rank transformation to rank the data and then filter out the duplicates based on the rank.

• Use the Lookup transformation to check for duplicat...read more
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Q3. Informatica - How will you select last 10 lines from a file in mapping
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To select the last 10 lines from a file in Informatica mapping, use the Source Qualifier transformation with a SQL override.
• Add a Source Qualifier transformation to the mapping.

• In the Source Qualifier transformation, specify the file as the source and set the appropriate file properties.

• Write a SQL override in the Source Qualifier transformation to select the last 10 lines from the file.

• Use the ROWNUM pseudocolumn or t...read more
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Q4. Informatica - What are lookups and their types? Differences between those types in terms of input and output ports?
Ans. 
Lookups in Informatica are used to retrieve data from a reference table based on a matching condition.
• Lookups are used to perform data transformations and enrich the data in a mapping.

• There are three types of lookups in Informatica: Connected, Unconnected, and Static.

• Connected lookup returns multiple rows and can be used in any transformation.

• Unconnected lookup returns a single value and is used in expressions or trans...read more
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Q5. Informatica - Tell me about your experience of performance optimization of workflows/mappings
Ans. 
I have extensive experience in performance optimization of Informatica workflows and mappings.
• Identifying and resolving performance bottlenecks

• Tuning SQL queries and optimizing database connections

• Optimizing transformations and reducing data processing time

• Using partitioning and parallel processing for improved performance

• Monitoring and analyzing session logs and performance statistics

• Implementing caching and lookup op...read more
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Q6. Informatica - What is push down optimization?
Ans. 
Push down optimization is a technique used in Informatica to improve performance by pushing data transformation operations to the source or target database.
• Push down optimization reduces the amount of data transferred between the source and target systems.

• It allows the database engine to perform transformations, aggregations, and filtering, leveraging its processing power.

• By pushing down operations, Informatica minimiz...read more
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Q7. Unix - Display 10th line from a file
Ans. 
Display the 10th line from a file in Unix.
• Use the 'head' command to display the first 10 lines of the file.

• Then use the 'tail' command to display the last line from the first 10 lines.

• Combine both commands using a pipe ('|') to display the 10th line directly.
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Q8. Unix - Display duplicate lines from a file
Ans. 
Display duplicate lines from a file in Unix.
• Use the 'sort' command to sort the lines in the file.

• Use the 'uniq' command with the '-d' option to display only the duplicate lines.

• Redirect the output to a new file or display it on the console.
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Q9. Python - How to check if a string starts with letter 'a' and then has 4-8 'd' after that.
Ans. 
The Python code to check if a string starts with 'a' and has 4-8 'd' after that.
• Use the startswith() method to check if the string starts with 'a'.

• Use the count() method to count the occurrences of 'd' in the string.

• Check if the count of 'd' is between 4 and 8 (inclusive).
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Q10. Unix - how to find disk usage of a specific directory
Ans. 
To find disk usage of a specific directory in Unix, use the 'du' command.
• Open the terminal and navigate to the desired directory

• Run the 'du' command followed by the directory path

• The command will display the disk usage in bytes for each file and subdirectory within the specified directory

• To get the disk usage in human-readable format, use the '-h' option with 'du'

• To sort the output by disk usage, use the '-s' option wi
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Q11. SQL - what happens in a left join
Ans. 
In a left join, all the rows from the left table are included in the result set, along with matching rows from the right table.
• Left join returns all rows from the left table and the matching rows from the right table

• If there is no match, NULL values are returned for the columns of the right table

• Left join is used to retrieve data from multiple tables based on a related column
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Q12. Cloud Computing - Concepts of CapEx and OpEx
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Q13. Cloud Computing - Concepts of IaaS, PaaS, SaaS
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Q14. Cloud Computing - Concepts of Private, Public and Hybrid cloud
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Q1. Behavioral - How would you handle a scenario where client expectations haven't been met at the end of development period? Give an example if you have faced it.
Ans. 
I would address the issue by identifying the root cause, communicating with the client, and implementing necessary changes.
• Identify the reasons for not meeting client expectations

• Communicate with the client to understand their concerns and expectations

• Evaluate the development process and identify areas for improvement

• Implement necessary changes to meet client expectations

• Ensure effective communication and collaboration...read more
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Q2. Behavioral - How would you handle a scenario where a change in process has significantly impacted your team workings? Give an example if you have faced it.
Ans. 
I would handle the scenario by following a structured approach and effectively communicating with the team.
• Assess the impact of the change on team workings

• Identify the key challenges and areas of concern

• Develop a structured plan to address the issues

• Communicate the plan to the team and seek their input

• Implement the plan while providing necessary support and guidance

• Monitor the progress and make adjustments as needed

• Reg...read more
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Q3. Behavioral - How would you handle a scenario where a lot of interactions have to be done with different teams/stakeholders to complete the work? Give an example if you have faced it.
Ans. 
I would handle the scenario by following a structured approach and effective communication.
• Identify all the teams and stakeholders involved

• Establish clear communication channels

• Schedule regular meetings to discuss progress and address any issues

• Document and track all interactions and decisions

• Ensure everyone is aligned on goals and expectations

• Provide regular updates and status reports

• Resolve conflicts or disagreements...read more
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Q4. Cloud Computing - Why do you think Cloud is a better choice than on-premise datacenters
Ans. 
Cloud computing offers scalability, cost-effectiveness, flexibility, and improved security compared to on-premise datacenters.
• Scalability: Cloud allows easy scaling up or down of resources based on demand.

• Cost-effectiveness: Cloud eliminates the need for upfront hardware and infrastructure investments.

• Flexibility: Cloud enables easy access to data and applications from anywhere, anytime.

• Improved security: Cloud provide...read more
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Q5. SQL - Tell me your experience with performance optimization in SQL
Ans. 
I have extensive experience in performance optimization in SQL.
• Identifying and optimizing slow queries

• Creating and maintaining appropriate indexes

• Using query execution plans to identify bottlenecks

• Optimizing database schema and table design

• Using appropriate data types and constraints

• Caching and data caching techniques

• Partitioning large tables

• Optimizing query parameters and joins

• Using stored procedures and views for per
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Q6. Questions from my past projects regarding the architecture of datawarehouses we had.
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Q1. What is Object-Oriented Programming (OOP), and can you explain its fundamental concepts?
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Q2. What is the definition of an array, and what are the different types of arrays?
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Q3. What is the clr
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The content is based on HTML, Windows, and ADO.NET.

Q1. What motivates you to pursue this job?
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Q2. What is your expected salary?
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Request to write procedures for React, Node, and MySQL.

Discussed the terminologies related to the job position, such as securing data and handling large datasets.

Q1. What is your reason for seeking a change in your current position?
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Q2. What is the reason for your job changes approximately every 2.5 years?
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Q1. It was a online coding round with one question related to a medium hard binary search question..
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Q2. The second question was bit ambiguous question involving a tree, where we were asked to add a tree child and subchild in the form a a directory and subdirectory
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