Amazon Technical Operations Engineer Interview Questions and Answers

Q1. Components of service
Ans. 
Components of a service include functionality, reliability, availability, and performance.
• Functionality: The service should perform the intended tasks and meet the requirements.

• Reliability: The service should consistently deliver the expected results.

• Availability: The service should be accessible and operational when needed.

• Performance: The service should perform efficiently and meet performance expectations.
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Q2. Lifecycles of web api
Ans. 
The lifecycle of a web API refers to the stages it goes through from development to retirement.
• The lifecycle typically includes stages like planning, development, testing, deployment, and retirement.

• During planning, the requirements and design of the API are defined.

• Development involves writing the code and implementing the functionality.

• Testing ensures the API works as expected and meets the requirements.

• Deployment in...read more
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Round duration - 60 minutes
Round difficulty - Medium

Technical Interview round with questions on C#, Design patterns, OOPS etc.

Q1. What is a base class?
Ans. 
A base class is a class that is used as a starting point for creating other classes. It can be inherited by other classes.
• Base class provides common attributes and methods that can be inherited by other classes

• Derived classes can extend or override the functionality of the base class

• Example: Animal can be a base class with attributes like name and methods like eat, sleep
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Q2. What is a singleton design pattern?
Ans. 
Singleton design pattern ensures a class has only one instance and provides a global point of access to it.
• Used to restrict the instantiation of a class to one object

• Commonly used in logging, caching, thread pools, database connections

• Implemented by creating a static instance of the class and a private constructor to prevent external instantiation
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Q3. What are the different access modifiers in C#?
Ans. 
Access modifiers in C# control the visibility and accessibility of classes, methods, and other members.
• Public - accessible from any other class or assembly

• Private - accessible only within the same class

• Protected - accessible within the same class or derived classes

• Internal - accessible within the same assembly

• Protected Internal - accessible within the same assembly or derived classes
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Q4. What is the default access modifier in C#?
Ans. 
The default access modifier in C# is 'private'.
• Default access modifier is applied if no access modifier is specified for a class member

• It restricts the access to the member within the same class

• Example: private int myVariable = 10;
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45 min round. Similar to Leetcode medium level question.

45 min coding round, 2 question asked

Q1. System design of proximity service
Ans. 
Design a system for proximity service
• Utilize geolocation data to track user locations

• Implement algorithms to calculate proximity between users

• Use real-time updates to notify users of nearby contacts
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Q1. Behavioral questions
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Q1. What is ACID in DBs ?
Ans. 
ACID stands for Atomicity, Consistency, Isolation, and Durability in databases.
• Atomicity ensures that all operations in a transaction are completed successfully or none at all.

• Consistency ensures that the database remains in a consistent state before and after the transaction.

• Isolation ensures that multiple transactions can be executed concurrently without affecting each other.

• Durability ensures that once a transaction...read more
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Q2. What is the difference in checked and unchecked exceptions ?
Ans. 
Checked exceptions are checked at compile time while unchecked exceptions are not checked at compile time.
• Checked exceptions are subclasses of Exception class except RuntimeException and its subclasses.

• Unchecked exceptions are subclasses of RuntimeException and Error classes.

• Checked exceptions must be caught or declared in the method signature using 'throws' keyword.

• Unchecked exceptions do not need to be caught or decl...read more
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Q3. Find the min difference between any two integers of 2 sorted list
Ans. 
To find the minimum difference between any two integers of 2 sorted lists, iterate through both lists simultaneously and keep track of the minimum difference.
• Iterate through both sorted lists simultaneously

• Keep track of the minimum difference found so far

• Update the minimum difference if a smaller difference is found
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Q1. Print the nodes of a n-ary tree in an arc wise manner as seen from the outside.
Ans. 
Print nodes of n-ary tree in arc wise manner from outside
• Traverse the tree level by level from outside to inside

• Use a queue to keep track of nodes at each level

• Print the nodes at each level in a clockwise or anticlockwise manner
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It was a ideal machine coding round. Consisting of a question to be completed within 45 mins. For a given manager to employee hierarchy, count direct + indirect repartees.

Mostly DSA expect DP, graph problems

Q1. Graph traversal + DP
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Asked medium level graph question.

Asked LLD question with at flow executable.

Q1. Asked HLD questions.
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