Top 24
Prep plan
Updated weekly · Last refresh Aug 30

T-Mobile Data Engineer Interview Questions

The questions to prepare for a T-Mobile Data Engineer interview. Questions from real interview reports rank first. Updated weekly.

24questions
~4htotal time
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1
CodingStart here. 5 questions · ~48 min
Merge Two Sorted Linked ListsEasy
Practice

Merge two sorted singly linked lists into one sorted list by relinking existing nodes.

RecursionLinked ListsSortingT-Mobile
Python List vs Tuple UsageEasy

Compare Python lists and tuples, including mutability, performance, and when each should be used.

tupleslistsData StructuresT-Mobile
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2
SQL & Data Manipulation4 questions + 2 drills · ~58 min
SQL Duplicate DetectionEasy
Practice

Find duplicate customer profiles by grouping on identifying fields and returning only repeated records.

Group ByHavingAggregationsT-Mobile
Handling Missing and Dirty SQL DataMedium

Explain how to profile, clean, and standardize missing or dirty data before analysis.

Data WranglingCase WhenQualityT-Mobile
OLTP vs OLAP Database DesignMedium

Explain OLTP vs OLAP designs, including schema shape, workload patterns, and when each is appropriate in a data platform.

financial dataperformanceData ModelingT-Mobile
Monthly Sales Trends by CategoryMedium
Practice
Practice drill

Aggregate monthly sales by product category and use LAG to calculate month-over-month changes.

InfrastructureToolsData WranglingTotal Wine & MoreInc.Benjamin Moore
Contact Center Agent Performance MetricsHard
Practice
Practice drill

Compute daily agent call KPIs and SLA using joins, aggregations, and window ranking in a contact center model.

ETLAggregationsData ModelingADP
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3
Pipelines10 questions · ~95 min
Data Quality and Schema EvolutionMedium

Approach for handling schema changes and data quality checks in a high-volume data lake pipeline.

schema evolutionData ModelingQualityT-Mobile
Preferred ETL and Transformation ToolsEasy

Explain your preferred extraction and transformation stack, and the reasoning behind those tool choices.

ToolsETLELTT-Mobile
Diagnose an Integration Pipeline IssueMedium

Structured approach to diagnose failures in an ETL integration, from source extraction through orchestration, data quality, and idempotent recovery.

ToolsDependenciesQualityT-Mobile
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4
Behavioral & Leadership5 questions · ~48 min
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The finish line: interview-readyComplete all 24 questions plus 2 hands-on drills to finish this plan.