A Software Engineer at Switch plays a vital role in designing, building, and maintaining the mission-critical software systems that power some of the most advanced data centers in the world. Unlike traditional software companies, Switch operates at the intersection of massive physical infrastructure, advanced networking, and high-density colocation. The engineering team is responsible for developing internal automation tools, monitoring platforms, and data center infrastructure management (DCIM) software that ensure 100% uptime and optimal resource utilization across millions of square feet of data center space. As a Software Engineer, your work directly impacts the efficiency, security, and scalability of the services provided to global enterprise clients. You will write code that communicates with industrial mechanical systems, monitors vast fiber-optic networks, and automates complex system provisioning workflows. This requires building highly reliable, real-time systems that can handle massive data streams from physical hardware and translate them into actionable operational insights. This role is both challenging and highly rewarding because it demands a deep understanding of how software interacts with physical environments. You will collaborate closely with Systems Engineers, network architects, and facility managers to solve complex engineering challenges.
Recruiter Screen
reportedInitial contact with the recruiter to discuss the candidate's background and fit for the role.
What to demonstrate
- Initial contact with the recruiter to discuss the candidate's background and fit for the role
- Depth in Object-Oriented Programming (OOP)
How to prepare
- Be able to walk your CV end to end in two minutes, and say why this company specifically.
- Have your salary expectations, notice period and location constraints ready, and ask for the rest of the loop in writing.
Technical Phone Interview
reportedA conversation with the hiring manager focusing on background, software design philosophy, and systems automation.
What to demonstrate
- A conversation with the hiring manager focusing on background, software design philosophy, and systems automation
- Depth in Object-Oriented Programming (OOP)
How to prepare
- Answer aloud and timed: Discuss a scenario where you had to refactor a procedural script into a clean, maintainable object-oriented codebase.
- Answer aloud and timed: What are the advantages and disadvantages of using object-oriented Perl compared to other modern object-oriented languages?
Take-Home Coding Challenge
reportedAssignment of a coding challenge to assess practical coding standards and problem-solving abilities.
What to demonstrate
- Assignment of a coding challenge to assess practical coding standards and problem-solving abilities
- Depth in Object-Oriented Programming (OOP)
How to prepare
- Answer aloud and timed: Describe how you would build a robust monitoring script to check the health of thousands of networked devices simultaneously.
- Answer aloud and timed: How do you handle concurrency and multi-threading in your automation scripts to prevent performance bottlenecks?
In-Person Interview
reportedAn interview at a Switch facility involving the hiring manager and a senior developer, discussing the coding challenge solution and technical requirements.
What to demonstrate
- An interview at a Switch facility involving the hiring manager and a senior developer, discussing the coding challenge solution and technical requirements
- Depth in Object-Oriented Programming (OOP)
How to prepare
- Answer aloud and timed: Explain your approach to parsing and processing large volumes of system log files in real time.
- Answer aloud and timed: What strategies do you use to ensure your automation tools fail gracefully without disrupting critical data center operations?
PracHub editorial advice for the preparation topics above.
Brush up on OOP fundamentals
Be prepared to discuss object-oriented design in detail. Even if your primary experience is in procedural scripting, you must demonstrate that you understand how to structure code cleanly using classes, inheritance, and design patterns.
Emphasize adaptability
If you encounter a language or tool in the interview that you haven't used before, focus on your ability to learn quickly. Draw parallels between your existing toolkit and the required technology to show you can ramp up fast.
Ask clarifying questions
During the coding challenge and technical discussions, do not hesitate to ask for clarification on system constraints, expected inputs, and error handling requirements. This shows you approach problems methodically.
Choose a category, try a prompt, then open its approach, worked solution or follow-up when you need it.
How do you handle concurrency and multi-threading in your automation scripts to prevent performance bottleneck
How do you handle concurrency and multi-threading in your automation scripts to prevent performance bottlenecks?
Approach
- Say what the runtime actually does before reasoning about the code.
- Name what is shared across threads and what owns each piece of state.
- Identify the window where an invariant is briefly untrue.
- Distinguish a value from a reference to it, and say which one you handed out.
Follow-up
- What happens if two callers reach this at the same time?
- Where could this allocate more than you expect?
Describe a complex technical bug you encountered in a previous role and the systematic process you used to dia
Describe a complex technical bug you encountered in a previous role and the systematic process you used to diagnose and resolve it.
Approach
- Restate the input: its shape, its size, and what is guaranteed about it.
- Name the brute-force solution and its complexity before improving on it.
- Choose the data structure from the access pattern, not from familiarity.
- State the target complexity and say which constraint rules the naive version out.
Follow-up
- How does this change if the input no longer fits in memory?
- What is the worst case, and how likely is it on real data?
Collapse a redelivered event batch into per-aggregate high-water marks
You drain a batch of up to 5,000,000 events, each (aggregate_id BIGINT, aggregate_version INT, event_type, payload). The log guarantees order within one aggregate only; the batch merges 64 partitions, and a relay failover has redelivered a range, so an older version for an aggregate can appear after a newer one. Given a map of last_applied_version per aggregate, produce the events worth applying, at most one per (aggregate_id, version), plus the count discarded. Target O(n) time. State the memory for 2,000,000 distinct aggregates and what you do when it does not fit.
Approach
- One pass, one hash map from aggregate_id to the highest version kept, and a discard counter. An event whose version is at or below last_applied_version for its aggregate is dropped without further work, which is the whole reason the event carries its version rather than a delta. O(n) expected time, O(d) space in distinct aggregates.
- Keep the maximum, never the last occurrence. The redelivered range means the final appearance of an aggregate in the batch can be an older version than one seen earlier in the same batch, so last-wins applies stale state over newer state and the projection regresses with no error anywhere.
- Cost the memory instead of calling it large: an 8-byte key plus a 4-byte version is 12 bytes of payload, and an open-addressed table held at a 0.7 load factor costs roughly 17 bytes per entry before per-slot metadata, so 2,000,000 aggregates is tens of megabytes in a native layout and several times that in a runtime that boxes both key and value.
- If the distinct set exceeds memory, partition on hash(aggregate_id) mod P and reduce each partition independently. Every event for one aggregate hashes to the same partition, so the per-partition result is exact and the merge is concatenation rather than a second reduction.
Follow-up
- The payload is a patch rather than a snapshot, so applying only the highest version loses the intermediate changes. What changes in your reduction?
- How do you detect that version 7 arrived while version 6 was never delivered, and what should the consumer do about the gap?
How do you optimize a script or query that is running slowly in a production environment?
How do you optimize a script or query that is running slowly in a production environment?
Approach
- Name the grain you start from and join outward from it.
- Check whether any join is one-to-many before aggregating, or the sums inflate.
- Say which index the query would use, and what makes it unusable.
- Handle the rows that do not match: that is usually the actual question.
Follow-up
- How does the query change if that join becomes one-to-many?
- What happens to this when the table is ten times larger?
Explain why the owner filter ignores the listing index
The only index on resource is (tenant_id, status, updated_at DESC, resource_id DESC). A new endpoint returns one user's resources across all statuses, newest created first: WHERE tenant_id = $1 AND owner_user_id = $2 ORDER BY created_at DESC LIMIT 20. On a tenant with 2M rows it takes 900 ms and EXPLAIN shows a sort above a large scan. Explain precisely why the existing index cannot serve it, give the index that can, and state which of these the new index still will not help: owner_user_id alone across tenants; the same query ordered by updated_at. PostgreSQL 16.
Approach
- Separate the two jobs an index does. For filtering, a composite btree is seekable only on a left prefix, so with no predicate on status the scan can at best range over tenant_id and test owner_user_id per row; PostgreSQL 16 has no btree skip scan to jump the unconstrained column.
- For ordering, the index is sorted by (status, updated_at) within a tenant and not by created_at, so the LIMIT cannot stop early: every matching row is read and then sorted. That is the 'Sort Method: top-N heapsort' line, and it is why the plan reads 2M rows to answer with 20.
- Derive the replacement from the access path — equality, equality, then the ordering column: CREATE INDEX CONCURRENTLY ON resource (tenant_id, owner_user_id, created_at DESC). The scan seeks to the (tenant, owner) range and walks 20 entries in order, so the Sort node disappears along with the row-read.
- Treat INCLUDE (title, status) as conditional, not free. An index-only scan still visits the heap for any row whose page is not marked all-visible, so on a table taking 1.2k writes/second the win depends on autovacuum keeping the visibility map current, and the wider index costs more on every insert.
Follow-up
- 90% of rows are status='active'. Would a partial index WHERE status = 'active' change your answer, and for which of the three queries?
- A dashboard runs this for 40 owners in one page load. What changes about the design?
Explain the core pillars of object-oriented programming and how you have applied them in your past projects.
Explain the core pillars of object-oriented programming and how you have applied them in your past projects.
Approach
- Clarify what is being asked and what a complete answer contains.
- State your assumptions explicitly before working the problem.
- Say what you would check first and why it is the highest-information step.
- Work from the requirement backwards to the design.
Follow-up
- What assumption would you test first?
- How would you know your answer was wrong?
How would you implement object-oriented design patterns in a dynamic scripting language like Perl or Python?
How would you implement object-oriented design patterns in a dynamic scripting language like Perl or Python?
Approach
- Clarify what is being asked and what a complete answer contains.
- State your assumptions explicitly before working the problem.
- Say what you would check first and why it is the highest-information step.
- Work from the requirement backwards to the design.
Follow-up
- What assumption would you test first?
- How would you know your answer was wrong?
Discuss a scenario where you had to refactor a procedural script into a clean, maintainable object-oriented co
Discuss a scenario where you had to refactor a procedural script into a clean, maintainable object-oriented codebase.
Approach
- Clarify what is being asked and what a complete answer contains.
- State your assumptions explicitly before working the problem.
- Say what you would check first and why it is the highest-information step.
- Work from the requirement backwards to the design.
Follow-up
- What assumption would you test first?
- How would you know your answer was wrong?
What are the advantages and disadvantages of using object-oriented Perl compared to other modern object-orient
What are the advantages and disadvantages of using object-oriented Perl compared to other modern object-oriented languages?
Approach
- Clarify what is being asked and what a complete answer contains.
- State your assumptions explicitly before working the problem.
- Say what you would check first and why it is the highest-information step.
- Work from the requirement backwards to the design.
Follow-up
- What assumption would you test first?
- How would you know your answer was wrong?
Describe how you would build a robust monitoring script to check the health of thousands of networked devices
Describe how you would build a robust monitoring script to check the health of thousands of networked devices simultaneously.
Approach
- Clarify what is being asked and what a complete answer contains.
- State your assumptions explicitly before working the problem.
- Say what you would check first and why it is the highest-information step.
- Work from the requirement backwards to the design.
Follow-up
- What assumption would you test first?
- How would you know your answer was wrong?
Explain your approach to parsing and processing large volumes of system log files in real time.
Explain your approach to parsing and processing large volumes of system log files in real time.
Approach
- Clarify what is being asked and what a complete answer contains.
- State your assumptions explicitly before working the problem.
- Say what you would check first and why it is the highest-information step.
- Work from the requirement backwards to the design.
Follow-up
- What assumption would you test first?
- How would you know your answer was wrong?
What strategies do you use to ensure your automation tools fail gracefully without disrupting critical data ce
What strategies do you use to ensure your automation tools fail gracefully without disrupting critical data center operations?
Approach
- Clarify what is being asked and what a complete answer contains.
- State your assumptions explicitly before working the problem.
- Say what you would check first and why it is the highest-information step.
- Work from the requirement backwards to the design.
Follow-up
- What assumption would you test first?
- How would you know your answer was wrong?
Walk us through your solution to the coding challenge, explaining your architectural choices and data structur
Walk us through your solution to the coding challenge, explaining your architectural choices and data structure decisions.
Approach
- Fix the scope first: who calls this, how often, and what they do when it fails.
- Name the read and write paths separately; they rarely have the same bottleneck.
- Choose a partition key and say what query it makes expensive.
- State the consistency you need, and where you are willing to be stale.
Follow-up
- What breaks first when traffic grows ten times?
- How does this behave when that dependency is down for an hour?
p99 jumped on one listing filter while p50 stayed flat
After a release that added an owner_user_id filter to the resource listing, p99 rose from 90 ms to 1.9 s while p50 stayed at 40 ms. Traffic and row counts are unchanged. resource carries the index (tenant_id, status, updated_at DESC, resource_id DESC). The new query filters tenant_id and owner_user_id, orders by updated_at DESC, resource_id DESC, and takes 20 rows. On PostgreSQL, explain the shape of the regression, prove it from a query plan, and give the index you would add.
Approach
- Start from the shape. A flat p50 with a moved p99 means a subset of requests changed cost, not all of them, so the first job is naming the subset. Bucket the endpoint's latency by the tenant's row count; the natural hypothesis is that large tenants are a small share of requests and all of the tail.
- Get the plan for the new query on a large tenant with EXPLAIN (ANALYZE, BUFFERS). Expect an index scan over the tenant's range, a filter discarding most of it, then a Sort feeding the Limit, possibly reporting Sort Method: external merge Disk. Read actual rows on the scan node, not estimated.
- Explain why the existing index cannot serve it. A composite B-tree is seekable only as a left prefix, and with no equality predicate on status the scan cannot treat updated_at as an ordering, because rows in the tenant's range are ordered by status first. Everything matching must be read and sorted before LIMIT 20 can apply, so a tenant with 400,000 rows pays 400,000 rows to return 20.
- Add (tenant_id, owner_user_id, updated_at DESC, resource_id DESC). Equality on the first two columns leaves the index ordered by updated_at within that pair, so the plan becomes an index scan that stops after 20 rows with no Sort node. PostgreSQL can scan a B-tree backwards, so the DESC markers matter only if the two sort columns ever disagree in direction; keeping them explicit documents the order the keyset cursor depends on.
Follow-up
- The endpoint paginates with OFFSET. What does page 500 cost with your index, and what does the keyset version cost?
- How would you have caught this before release, given that a 10,000-row seed database produces the same plan shape at an unnoticeable cost?
Built from the rounds and topics Switch candidates report.
Prepare, practise & reflect
One practical outcome each day. Spend longer where you need it.
0 / 7 done01Map the Switch loop
- Write out the reported sequence: Recruiter Screen, Technical Phone Interview, Take-Home Coding Challenge, In-Person Interview.
- For each round, write one sentence on what it is judging, from the description above, and mark the one you are least ready for.
Deliverable: A one-page map of the 4 reported rounds, with the weakest marked.
02Work Object-Oriented Programming (OOP)
- Spend the session on Object-Oriented Programming (OOP), which Switch candidates report being tested on.
- Write one worked example in Object-Oriented Programming (OOP) and time yourself on it.
Deliverable: One timed worked example in Object-Oriented Programming (OOP).
03Work Network Infrastructure Management
- Spend the session on Network Infrastructure Management, which Switch candidates report being tested on.
- Write one worked example in Network Infrastructure Management and time yourself on it.
Deliverable: One timed worked example in Network Infrastructure Management.
04Work Network Engineering
- Spend the session on Network Engineering, which Switch candidates report being tested on.
- Write one worked example in Network Engineering and time yourself on it.
Deliverable: One timed worked example in Network Engineering.
05Answer out loud: Object-Oriented Programming & Scripting
- Answer aloud, timed: Explain the core pillars of object-oriented programming and how you have applied them in your past projects.
- Answer aloud, timed: How would you implement object-oriented design patterns in a dynamic scripting language like Perl or Python?
Deliverable: Spoken answers to 2 reported Object-Oriented Programming & Scripting question(s), under time.
06Answer out loud: Systems & Automation
- Answer aloud, timed: Describe how you would build a robust monitoring script to check the health of thousands of networked devices simultaneously.
- Answer aloud, timed: How do you handle concurrency and multi-threading in your automation scripts to prevent performance bottlenecks?
Deliverable: Spoken answers to 2 reported Systems & Automation question(s), under time.
07Answer out loud: Problem-Solving & Coding Challenges
- Answer aloud, timed: Walk us through your solution to the coding challenge, explaining your architectural choices and data structure decisions.
- Answer aloud, timed: How do you optimize a script or query that is running slowly in a production environment?
Deliverable: Spoken answers to 2 reported Problem-Solving & Coding Challenges question(s), under time.
Expand any day for tasks and deliverables. Your progress is saved on this device.
Behavioural rounds judge the decision you made and what it cost.
Ship under a deadline and bound the debt you chose
You have four days to ship a tenant-facing listing endpoint. The version you would defend uses keyset pagination over (tenant_id, status, updated_at DESC, resource_id DESC); the version you can finish uses LIMIT/OFFSET with no matching index. Describe a deadline call you actually made of this shape: what you shipped, what you knowingly deferred, how you bounded the damage with a mechanism rather than an intention, and the specific numeric condition that would force the follow-up. Name who you told and where you wrote it down.
Approach
- Name the deferred failure precisely instead of calling it slow. OFFSET n makes the database produce and discard n rows, so cost grows with page depth; without an index matching the sort, every matching row is read and sorted before the limit applies; and rows inserted between two page fetches shift across the boundary so items are skipped or repeated with nothing in the response to signal it.
- Bound the blast radius with something mechanical rather than a promise: cap maximum page depth, cap page size, restrict the endpoint to one internal caller, or keep it behind a flag. State which failure each cap removes and which it leaves standing.
- Attach a number to the trigger and wire it to an alarm: the first tenant crossing N resources, or the endpoint's p99 crossing its share of the 400 ms budget, so the debt announces itself instead of waiting to be remembered.
- Write it where the next engineer looks, which is the code and the ticket, not a chat message: what was deferred, why, the cap, and the trigger.
Follow-up
- At what page depth does the offset version breach your latency budget, given your page size and row counts?
- What breaks first when you switch to keyset pagination later, and what does a client holding an old page token see?
Argue against a design, lose, and commit anyway
Describe a design you argued against and lost. State the failure you predicted as a named mechanism, not a feeling about complexity: two services that would need one transaction, a projection with no rebuild path, a write path with no idempotency key. Say what evidence you brought, what the decision maker weighed instead, and what you did after the decision was made: what you instrumented, what you wrote down, and whether the prediction came true. Five minutes.
Approach
- State the prediction in falsifiable form up front: the mechanism, the condition that triggers it, and the observable outcome. A prediction that cannot be checked also cannot be credited to you later.
- Show the evidence you had at the time and label each piece honestly as measured, analogous, or intuition. Keeping the intuition is fine; disguising it as data is the thing that erodes your standing in the next argument.
- Represent the opposing case at full strength, including the constraint you did not control: a fixed date, a team boundary, or the fact that the decision was cheap to reverse and yours was not.
- Make disagree-and-commit concrete. Name the artefact you left behind so the prediction could be settled without you: the alert and its threshold, the counter on the dashboard, the decision note that recorded the trade-off and the condition that would revisit it.
Follow-up
- What threshold on that alert would have proved you right, and did anyone ever look at it?
- If the same proposal arrived tomorrow with the same deadline, would you argue it the same way?
Narrate an outage you owned from page to postmortem
Pick an incident you personally drove, ideally one where writes were affected rather than reads. In six to eight minutes: state the symptom as it first appeared on a dashboard, the blast radius you established before you knew the cause, the mitigation you applied and when, the mechanism you eventually proved, and the follow-up that would prevent a repeat. Bring numbers: error rate, tenants affected, minutes to mitigate, minutes to resolve. If you cannot name what you measured, choose a different incident.
Approach
- Open on the signal rather than the cause: which metric at which percentile moved, on which service, at what time, so the listener follows the same evidence you had rather than a conclusion you already reached.
- Separate mitigation from diagnosis out loud. State what you did to stop the bleeding (flag off, shed traffic, drain a lease, roll back a deploy) and say plainly that you did it before the mechanism was known, because those are two jobs with different deadlines.
- Establish blast radius in countable terms: how many tenants, how many writes, and crucially whether the effect was loss or only delay. An append-only revision table or a pending outbox row means the change survived and the projection was merely behind, which is a repair rather than a data-loss incident.
- Prove the mechanism instead of asserting it. Name the trace span that grew, the plan that flipped to a sequential scan, the lease that expired, plus one alternative you ruled out and the signal that stayed flat while you ruled it out.
Follow-up
- What would you do differently in the first five minutes, given the same dashboard and no more information?
- Which follow-up action did you deliberately not take, and why was dropping it the right call?
- 01
You have four days to ship a tenant-facing listing endpoint. The version you would defend uses keyset pagination over (tenant_id, status, updated_at DESC, resource_id DESC); the version you can finish uses LIMIT/OFFSET with no matching index. Describe a deadline call you actually made of this shape: what you shipped, what you knowingly deferred, how you bounded the damage with a mechanism rather than an intention, and the specific numeric condition that would force the follow-up. Name who you told and where you wrote it down.
- 02
Describe a design you argued against and lost. State the failure you predicted as a named mechanism, not a feeling about complexity: two services that would need one transaction, a projection with no rebuild path, a write path with no idempotency key. Say what evidence you brought, what the decision maker weighed instead, and what you did after the decision was made: what you instrumented, what you wrote down, and whether the prediction came true. Five minutes.
- 03
Pick an incident you personally drove, ideally one where writes were affected rather than reads. In six to eight minutes: state the symptom as it first appeared on a dashboard, the blast radius you established before you knew the cause, the mitigation you applied and when, the mechanism you eventually proved, and the follow-up that would prevent a repeat. Bring numbers: error rate, tenants affected, minutes to mitigate, minutes to resolve. If you cannot name what you measured, choose a different incident.
What is the technical stack for Software Engineers at Switch?
The technical stack at Switch is highly diverse and tailored to systems automation. It includes robust backend languages, databases, and scripting tools, with a notable footprint of object-oriented Perl and Python for legacy and modern automation frameworks.
Switch Software Engineer candidate reports ↗How important is knowledge of specific languages like Perl?
While deep expertise in Perl is highly valued due to existing systems, demonstrating strong object-oriented programming (OOP) principles in other languages like Python, C++, or Java is often sufficient. The key is proving you can quickly adapt your OOP knowledge to their specific stack.
Switch Software Engineer candidate reports ↗What is the typical timeline for the interview process?
The process generally takes about two to three weeks from the initial recruiter screen to the final decision, depending on how quickly you complete the take-home coding challenge and schedule the in-person interview.
Switch Software Engineer candidate reports ↗What is the work environment and culture like for engineers?
The culture is highly collaborative, pragmatic, and operations-focused. Engineers work closely with physical infrastructure teams, meaning your work has a direct, visible impact on the physical security and efficiency of the data centers.
Switch Software Engineer candidate reports ↗What topics does Switch test in interviews?
Switch interviews most often cover Object-Oriented Programming (OOP), Customer/Client Conflict Resolution, Structured Behavioral Interviewing (Competency Stories), Network Infrastructure Management, and Professional Communication (Spoken). The exact emphasis depends on the specific role you apply for.
Switch Software Engineer candidate reports ↗Sources & methodology 3 sources ↗
No official company page is cited. Rounds and questions come from candidate reports and PracHub editorial material; each source shows the date it was read.
- 01Switch Software Engineer candidate reports ↗
Company-reported rounds, questions and FAQ.
Candidate reports · Accessed 2026-09-22 - 02PracHub Software Engineer practice ↗
PracHub practice material, not company-reported.
PracHub page · Accessed 2026-09-22 - 03PracHub preparation framework ↗
PracHub preparation guidance.
PracHub page · Accessed 2026-09-22
Explore related engineering environments and compare the preparation focus.
Lambda Software Engineer Interview Guide
Failure-handling practice for Lambda software engineer candidates: requests whose outcome a timeout leaves unknown, where a retry is safe, and deduplicating at the receiver instead of assuming exactly-once delivery.
CoreWeave Software Engineer Interview Guide
Failure-handling practice for CoreWeave software engineer candidates: requests whose outcome a timeout leaves unknown, where a retry is safe, and deduplicating at the receiver instead of assuming exactly-once delivery.
Harvey Software Engineer Interview Questions & Guide 2026
Prepare for the software engineer interview at Harvey with original coding, system design and debugging exercises, each paired with a worked solution and the reasoning behind it.
X: The Moonshot Factory Software Engineer Interview Guide
What X: The Moonshot Factory asks Software Engineer candidates, from reported rounds and questions.