Describe and analyze your hands on experience designing, operating, and maintaining infrastructure and systems. Candidates should be prepared with three to four concrete examples of systems or infrastructure projects they directly contributed to, including quantitative scale metrics such as user counts, requests per second, data volumes, throughput, and geographic distribution. Discuss architecture decisions and trade offs, component choices, platform boundaries, and how the design met requirements for scalability, reliability, performance, and security. Cover operational aspects such as deployments, configuration management, automation and infrastructure as code, monitoring and observability, incident response and remediation, capacity planning, and disaster recovery and business continuity. Include experience with large scale and multi region deployments, data center operations, networking at scale, and integration points. Also cover enterprise information technology topics where relevant, for example servers and endpoints, storage systems, networking hardware, identity and access infrastructure such as Active Directory, firewalls, routers and switches, and the differences and migration considerations between on premise and cloud infrastructure. Be ready to explain specific challenges faced, how issues were diagnosed and resolved, trade offs made, and the candidate's exact role and contributions.
HardSystem Design
23 practiced
Design a globally available customer-facing service that must survive a full regional outage and meet explicit targets for both service restoration and acceptable data loss. Walk through the main architectural decisions, the failure modes you would plan for, and where you would accept tradeoffs between automation, complexity, and consistency.
Sample Answer
**Design recommendation**For a customer-facing global service, I would design for regional failure first, not just instance failure. The core pattern is a multi-region architecture with stateless application tiers deployed in at least two regions, global traffic routing, and data replication matched to the business RTO and RPO targets.**Main decisions**- Use global load balancing or DNS steering to send users to the healthiest region- Keep the application tier stateless so traffic can move quickly- Choose the data model carefully. If the app can tolerate some data lag, asynchronous replication is simpler. If not, the consistency cost is higher.- Automate failover, but keep a manual override for dangerous edge cases like bad data pushes or split-brain conditions**Failure modes to plan for**- Full region outage- Partial brownouts, where the region is up but slow- Database replica lag- Control plane issues in the cloud provider- Corrupted deploys or bad configuration propagated to both regions**Tradeoff example**If the target is RTO 15 minutes and RPO 5 minutes, asynchronous replication may be acceptable. If the business wants zero data loss, I would explain that strong consistency across regions increases latency and complexity, especially for write-heavy workloads.My recommendation would be easy to operate, documented with clear recovery steps, and tested with regular failover exercises so the team trusts it before a real outage happens.
MediumTechnical
23 practiced
A platform team wants a repeatable way for dozens of engineering groups to provision environments for development, testing, and production with guardrails, auditability, and minimal drift. What architecture and operating model would you propose so provisioning stays fast for developers while still being safe for operations?
Sample Answer
**Recommended architecture**I would propose a platform engineering model built on infrastructure as code, policy as code, and self-service templates. Infrastructure as code means environments are created from versioned definitions, not manual clicks. Policy as code means guardrails are checked automatically before deployment.**Operating model**- Platform team owns the base landing zones, network patterns, security controls, and approved modules- Product teams request environments through a catalog or Git workflow- Dev, test, and prod use the same core pattern, but prod has stricter approvals and controls- Drift detection runs continuously so manual changes do not silently diverge from source control**Worked example**A team requests a new test environment with one app cluster, one database, and private network access only. The pipeline deploys from a standard module, applies tagging, creates audit logs, and blocks any public database exposure. If someone changes the firewall by hand, the next drift check flags it.**Why this works**It keeps provisioning fast for developers, because they use preapproved building blocks, while operations gets repeatability, traceability, and fewer surprise configurations. It also scales better than one-off scripts because every environment is built from the same trusted blueprint.
EasyBehavioral
24 practiced
Tell me about one systems or infrastructure project you personally contributed to from the requirements phase through production. What was the scale of the environment, what exactly did you own, and what measurable impact did the design or operational changes have on reliability, performance, or cost?
Sample Answer
**Project**I helped design and roll out a standardized cloud landing zone for a mid-sized organization that was moving from mostly manual infrastructure to repeatable environments.**What I owned**I worked from requirements through production: I gathered security and network needs, defined the reference architecture, partnered with engineers on implementation, and helped validate the cutover plan. I also documented the design so other teams could reuse it.**Scale**The environment supported multiple application teams, separate dev and prod spaces, centralized logging, and controlled network access across a mix of internal and customer-facing workloads.**Action and impact**- I pushed for infrastructure as code instead of manual setup- I standardized network segmentation and access controls- I helped add monitoring and change tracking before go-liveThis reduced manual provisioning from something that took most of a day to something the teams could request through a repeatable workflow, and it cut down configuration mistakes because the same blueprint was used every time.What I learned is that good architecture is not just technically correct. It has to be operationally repeatable, or it will not hold up in production.
MediumTechnical
20 practiced
A client has an on-prem environment built around directory services, shared file storage, firewalls, routers, switches, and a mix of servers and endpoints. They want to move some workloads to cloud without a risky cutover. How would you decide what to migrate first, what dependencies to map, and what risks to call out in the first review?
Sample Answer
**What I would migrate first**I would start with low-risk, loosely coupled workloads such as development, test, batch jobs, or a small stateless application. I would avoid moving identity, shared file storage, or tightly coupled databases first because those usually carry the most hidden dependencies.**Dependency mapping**I would inventory:- Directory services and authentication flows- DNS, NTP, and certificate services- File shares and application-specific storage- Firewall rules, service accounts, and hard-coded IPs- Backup, monitoring, and licensing dependencies**First review risks**The biggest risks are identity mismatch, application latency to on-prem services, file locking behavior, and overlooked network rules. Shared storage is especially risky because it often hides business logic and access patterns.**Example**If a web app only needs read-only LDAP access and stores logs locally, it is a good pilot. If it depends on a file share with frequent locking and a legacy SQL server on-prem, I would flag it as a later-phase migration.**How I would present it**I would recommend a landing zone first, then a pilot migration with one noncritical workload, and only after that a phased wave plan. That gives the customer a controlled path, clearer risk visibility, and no risky cutover from day one.
MediumTechnical
20 practiced
Tell me about a time you had to explain an infrastructure recommendation to a sales team or customer who wanted a quick answer, but the technical risk was still uncertain. How did you frame the tradeoffs, avoid overcommitting, and keep the deal or project moving forward?
Sample Answer
**Situation**A sales team wanted a fast yes on a multi-region design for a customer, but the app still had unclear security and integration requirements.**Task**My job was to keep momentum without promising an architecture that might fail later.**Action**- I framed the answer as options with assumptions, not a hard commitment- I explained the tradeoff between a quick, low-risk baseline and a more complex active-active design- I gave the sales team a short list of discovery questions that would let us finalize the recommendation quickly- I documented what was confirmed versus what was still open, so everyone had the same story**Example**I told the customer, in effect, that we could support two regions, but the final pattern depended on whether they needed near-zero data loss, what integrations were synchronous, and whether any data had residency constraints.**Result**The deal stayed moving because we gave a credible path forward instead of a false certainty. The customer trusted the recommendation more because we were honest about risk, and the sales team had a clear next step instead of a vague technical delay.That experience reinforced that good architecture selling is not saying yes quickly. It is helping the customer make a safe decision quickly.
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