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Quest Diagnostics Software Engineer Interview Questions

The questions to prepare for a Quest Diagnostics Software Engineer interview. Questions from real interview reports rank first. Updated weekly.

30questions
~4htotal time
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1
CodingStart here. 9 questions · ~79 min
Linked List ReversalEasy
Practice

Reverse a singly linked list in-place using iterative pointer manipulation.

RecursionLinked ListsArraysQuest Diagnostics
Java 8 vs Earlier VersionsEasy

Compare Java 8 with earlier Java versions, focusing on lambdas, functional interfaces, streams, and API improvements.

javabasicstechnical fundamentalsQuest Diagnostics
Interface Polymorphism and AbstractionEasy

Tests understanding of OOP concepts used in enterprise Java systems.

TreesGraphsQuest Diagnostics
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2
SQL & Data Manipulation3 questions + 3 drills · ~56 min
Optimize a Slow SQL QueryMedium

Tests SQL performance troubleshooting and query optimization strategies.

Window FunctionsJoinsAggregationsQuest Diagnostics
Primary Key vs Unique KeyEasy

Tests database schema knowledge and constraints relevant to data integrity.

JoinsData WranglingQuest Diagnostics
SQL Server Performance TuningMedium

Tests your ability to diagnose and optimize SQL Server performance in production systems.

sql performanceQuest Diagnostics
Top Daily Rides by VehicleMedium
Practice
Practice drill

Rank the top 3 completed rides per vehicle per day using joins, a CTE, and ROW_NUMBER.

Window FunctionsJoinsData WranglingWaymo
Deduplicate Out-of-Order Replication EventsMedium
Practice
Practice drill

Use ROW_NUMBER() to keep the earliest created_at 'Repl created' per entity and return out-of-order duplicates to delete.

Window FunctionsSubqueriesJoinsReplitQuantcast
Top Customers by Net SalesMedium
Practice
Practice drill

Compute top 10 customers by net sales using joins and aggregations, ordering by revenue with deterministic tie-breaking.

SubqueriesJoinsData WranglingGain DigitalTCSZest AI
3
Behavioral & Leadership16 questions · ~140 min
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4
More topics2 questions · ~18 min
Securing a REST APIHard

Tests secure API design, authentication, authorization, and threat mitigation for healthcare microservices.

InfrastructureNetworkingQuest Diagnostics
Java Memory ManagementMedium

Tests understanding of Java runtime memory management and garbage collection concepts.

Infrastructureos internalsQuest Diagnostics

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