Infrastructure Engineer

Why this role is hard · Ryan Mahoney

Hiring mid-level infrastructure engineers is tough because we need people who can work independently without losing sight of the bigger team picture. They should be building provisioning pipelines and setting up monitoring that catches problems before they escalate. The real test comes during an outage, where they actually listen to others and can clearly explain the fix to non-technical staff. We also need folks who care about long-term system stability instead of just slapping on quick patches. Plenty of applicants can write infrastructure code, but very few will own up to what they do not know and reshape their designs to fit real business needs.

Core Evaluation

Critical questions for this role

The competency and attitude questions below are where the hiring decision is made. They run in the live interview rounds and are calibrated to the level selected above.

16 Competency Questions

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Discipline
Infrastructure Engineering & Platform Operations
Job requirement
Infrastructure Automation & Compute Provisioning
Designs and maintains IaC templates; automates routine provisioning and scaling workflows across environments.
Expected at Mid
3 / 5
Mid-level engineers must independently design reusable automation templates and manage scaling workflows without step-by-step guidance to reduce manual toil.

Interview round: Hiring Manager Technical Deep Dive

Walk me through a recent initiative where you automated compute provisioning for a revenue-critical workload across multiple environments. How did you approach design, testing, and deployment?

Positive indicators

Mentions CI/CD integration for infrastructure changes
Describes explicit testing stages for configuration validation
Highlights automated rollback mechanisms
References environment-specific parameterization strategies
Discusses post-deployment verification steps

Negative indicators

Relies on manual scripts or ad-hoc command execution
Ignores environment differences during promotion
Lacks automated testing or validation gates
Describes unversioned or loosely tracked configurations
Fails to mention rollback or recovery strategies

9 Attitude Questions

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Active Listening

Active Listening in infrastructure engineering is the disciplined practice of fully concentrating on, comprehending, and validating technical, operational, and stakeholder input before formulating responses or architectural decisions. It involves suspending immediate problem-solving to accurately capture nuanced constraints, implicit risks, and real-world operational realities, ensuring that system designs, scaling strategies, and incident responses are grounded in a complete, verified understanding of cross-functional requirements and systemic interdependencies.

Interview round: Recruiter Initial Screen

During an incident call, multiple stakeholders provide fragmented technical details and operational impacts simultaneously. How would you manage the information flow and confirm the facts?

Positive indicators

Implements a structured turn-taking approach
Paraphrases complex updates for confirmation
Separates technical symptoms from operational impacts

Negative indicators

Interrupts speakers to assert authority
Accepts fragmented details without verification
Relies on memory instead of documenting inputs

Supporting Evaluation

How candidates earn the selection conversation

The goal is to reduce effort for everyone by collecting more useful signal before adding more interviews. Lightweight application prompts and structured screens help the panel focus live time on the candidates most likely to succeed.

Stage 1 · Application

Filter at the door

Runs the moment a candidate hits Submit. Disqualifying answers end the application; everything else is captured for review.

Knock-out Questions

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Application Screen: Knock-out

How many years of hands-on professional experience do you have designing and implementing disaster recovery, failover, and high-availability architectures for critical infrastructure?

Less than 2 years

Auto-decline

2 to 4 years

Qualifies

5 to 7 years

Qualifies

8 or more years

Qualifies

Video-Response Questions

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Application Screen: Video Response

Describe how you would communicate status and escalation paths to non-technical operations staff during a simulated fare system database corruption drill. What specific steps do you take to ensure everyone understands their roles despite the technical complexity?

Candidate experience

REC

0:42 / 2:00

1Record

2Review

3Submit

Response time

2 min

Format

Recorded video

Stage 2 · Resume Screening

Read the resume against fixed criteria

Reviewers score every application that clears the door against the same criteria. Stronger reviews advance to live interviews; weaker ones are archived without further screening.

Resume Review Criteria

8 criteria

Evidence of independently managing, optimizing, and troubleshooting specific infrastructure domains such as HA virtual machines, SAN storage, or database clusters.

Evidence of designing, testing, or automating failover runbooks, backup verification workflows, and infrastructure monitoring pipelines.

Evidence of forecasting compute/storage needs, coordinating maintenance windows with operational teams, and presenting upgrade or migration roadmaps.

Evidence of implementing network segmentation, zero-trust controls, or automated compliance checks for transactional and audit-sensitive environments.

Is the resume complete, well-organized, and free from formatting, spelling, and grammar mistakes?

Does the cover letter or personal statement convey clear relevance and familiarity with the job?

Does the resume show relevant prior work experience?

Does the resume indicate required academic credentials, relevant certifications, or necessary training?

Stage 3 · During Interviews

Where the hire is decided

Interview rounds use the competency and attitude questions outlined above, then add tests, work simulations, and presentations that reveal deeper evidence about how the candidate thinks and works.

Coding Test

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Live Interview · Coding Test

Without AI

Complete the script to parse simulated database latency logs, filter queries exceeding a threshold, aggregate by endpoint, and return a summary.
Write a Python function that processes a list of log dicts, filters by latency > 200ms, groups by endpoint, and calculates average latency and count per endpoint.

With AI

Use an AI assistant to generate the aggregation logic, then critically review it for memory efficiency with large logs and correct mathematical boundaries.
Generate Python code to filter logs by latency threshold, group by endpoint, and compute averages. Review the AI output for memory efficiency on large datasets, correct math, and clear error handling for missing fields.

Response time

20 min

Positive indicators

Efficient single-pass processing
Accurate aggregation with proper type handling
Clean, readable dictionary construction
Refactors AI output to use generators or efficient dict methods
Validates math against edge cases (e.g., division by zero)
Adds explicit field validation

Negative indicators

Multiple unnecessary iterations over logs
Missing type checks causing runtime errors
Incorrect averaging logic
Accepts memory-heavy intermediate lists
Misses division-by-zero or missing-key errors
Overcomplicates with unnecessary frameworks

Presentation Prompt

Prepare a short deck walking us through a past infrastructure project where you owned the reliability and high-availability strategy for a specific service domain. Discuss your implementation choices, trade-offs between performance and redundancy, and how you managed non-breaking change approvals.

Format

deck-and-walkthrough · 20 min · ~2 hr prep

Audience

Infrastructure engineering leads and cross-functional stakeholders.

What to prepare

3-5 slides summarizing the project context, your reliability architecture, key trade-offs, change approval process, and outcomes.

Deliverables

A short deck and a 15-20 minute verbal walkthrough.

Ground rules

Use only work you are permitted to share; redact sensitive IP, credentials, or internal metrics.
Focus on your personal contributions, decision-making process, and lessons learned.
Do not present theoretical or speculative work.

Scoring anchors

Exceeds: Demonstrates deep domain ownership, quantifies reliability outcomes, and clearly links architectural trade-offs to business and operational impact with a polished, audience-aware narrative.
Meets: Presents a coherent reliability strategy, acknowledges standard trade-offs, and explains change approval processes clearly with appropriate supporting visuals.
Below: Lacks clear ownership or decision rationale, glosses over failure scenarios, or struggles to connect technical choices to reliability outcomes.

Response time

20 min

Positive indicators

Clearly articulates RTO/RPO targets and how architecture decisions directly met them.
Balances performance tuning with redundancy mandates, explaining the operational impact of each choice.
Demonstrates structured change approval workflows and how risks were mitigated before deployment.
Effectively uses the deck to guide a logical, stakeholder-aware narrative without reading slides.

Negative indicators

Presents a generic infrastructure overview without demonstrating domain-specific ownership.
Overlooks trade-offs or presents them as purely technical without operational impact.
Fails to explain how non-breaking changes were validated, tested, or approved.
Deck is overly dense, disconnected from the verbal walkthrough, or relies heavily on unredacted internal data.

Work Simulation Scenario

Scenario. You own the GTFS-RT ingestion service domain. Product leadership has requested a new automated failover strategy to handle regional data center outages, but the initial request lacks RPO/RTO targets, budget constraints, and compliance boundaries.

Problem to solve. Scope the failover architecture, define acceptable data loss and recovery windows, and map out a phased implementation plan that balances performance tuning with rigid redundancy mandates.

Format

discovery-interview · 40 min · ~2 hr prep

Success criteria

Extract concrete RPO/RTO targets and compliance guardrails
Identify storage tiering and replication trade-offs
Draft a realistic implementation sequence with clear approval gates

What to review beforehand

Company transit data ingestion pipeline documentation
Standard disaster recovery and high-availability frameworks

Ground rules

Treat this as a scoping and discovery conversation with a domain owner
Drive the discussion by asking targeted questions to uncover constraints
You will not receive a complete requirements document; you must construct it through dialogue

Roles in scenario

Platform Engineering Manager (Maria Torres) (informed_partner, played by cross_functional)

Motivation. Validate that the engineer can independently scope complex reliability initiatives while balancing technical debt, compliance, and cross-team dependencies.

Constraints

Holds specific compliance mandates but will only share them when asked about data governance
Has budget constraints tied to non-breaking change approval cycles
Will not volunteer architectural preferences unless directly queried

Tensions to introduce

Product wants near-zero downtime, but current storage arrays have replication latency limits
Compliance requires air-gapped backups that complicate automated failover triggers
Adjacent teams are pushing for shared infrastructure that could introduce single points of failure

In-character guidance

Provide direct, honest answers to specific questions about compliance, budget, and current architecture
Reflect realistic operational friction when discussing cross-team dependencies
Remain neutral and let the candidate drive the scoping framework

Do not

Do not volunteer compliance mandates, budget limits, or architectural preferences without being asked
Do not steer the candidate toward a specific HA solution or replication technology
Do not complete the scoping exercise by providing a ready-made requirements list
Do not escalate hostility or artificially complicate the scenario beyond realistic cross-functional constraints

Scoring anchors

Exceeds: Proactively maps all technical, compliance, and budget constraints, articulates clear trade-offs, and designs a phased, audit-ready failover strategy with explicit decision gates.
Meets: Identifies key reliability constraints, asks relevant scoping questions, and outlines a logical implementation sequence that accounts for basic redundancy and compliance needs.
Below: Jumps to a technical design without asking about RPO/RTO or compliance, struggles to navigate conflicting requirements, or produces an unstructured, unrealistic plan.

Response time

40 min

Positive indicators

Asks precise questions to quantify RPO/RTO targets and compliance boundaries
Surfaces hidden trade-offs between replication latency, storage tiering, and automation complexity
Constructs a phased implementation plan with explicit decision gates and rollback criteria
Balances aggressive performance tuning with rigid redundancy and audit mandates

Negative indicators

Proposes a failover architecture without validating RPO/RTO or compliance constraints
Freezes when presented with conflicting technical and operational requirements
Ignores cross-team dependencies and assumes isolated infrastructure changes
Relies on generic HA patterns without tailoring to transit ingestion workloads

Progression Framework

This table shows how competencies evolve across experience levels. Each cell shows competency at that level.