Imperva India Site Reliability Engineer Interview: Rounds, Questions and Preparation

What the job involves

Site Reliability Engineers at global tech companies keep large-scale production systems fast, available, and efficient. Day to day they monitor services, respond to incidents, automate repetitive operations, and improve reliability through capacity planning and postmortems. Freshers usually start with monitoring, scripting, and on-call shadowing under senior SREs.

Role and technical knowledge

1. 1

   What does an SRE do that is different from a traditional sysadmin or DevOps engineer?

   Explain the focus on reliability as a software problem, using SLOs and automation. Mention that SREs write code to reduce toil and share ownership with developers.

2. 2

   Explain SLI, SLO, and error budget with a simple example from a web service.

   Define each term clearly and show how an error budget guides release decisions. Use a concrete example like 99.9 percent availability for a login service.

3. 3

   What happens when a service exceeds its error budget?

   Describe a freeze on new features until reliability improves, and a blameless review. Show that you understand the balance between velocity and stability.

4. 4

   How would you monitor a web application to detect a slow database query before users complain?

   Mention metrics like query latency percentiles, slow query logs, and alerting thresholds. Explain how you would set a baseline and alert on deviations.

Practical scenarios and troubleshooting

1. 5

   A website is intermittently returning 502 errors. Walk through your troubleshooting steps.

   Start with checking load balancer and backend health, then logs and metrics. Suggest isolating whether it is a network, application, or database issue.

2. 6

   You get an alert that disk usage on a production server is at 95 percent. What do you do first?

   Prioritise immediate mitigation like clearing logs or expanding storage, then investigate root cause. Mention safe commands and avoiding data loss.

3. 7

   How would you automate the deployment of a configuration change across 100 servers?

   Use configuration management or orchestration tools, with idempotent scripts and rollback plans. Highlight testing in staging before production.

4. 8

   A service is slow only for users in one geographic region. How do you investigate?

   Check latency metrics per region, DNS resolution, CDN behaviour, and network routes. Consider regional infrastructure or peering issues.

System design and reliability engineering

1. 9

   Design a simple highly available web service that can survive one data centre failure.

   Cover load balancing, multiple availability zones, database replication, and health checks. Mention trade-offs like cost and complexity.

2. 10

   How would you implement a canary deployment for a new version of a service?

   Explain routing a small percentage of traffic to the new version, monitoring key metrics, and rolling back automatically on failure. Mention feature flags if relevant.

3. 11

   What is chaos engineering and why would an SRE use it?

   Describe deliberately injecting failures to test resilience in a controlled way. Give an example like killing a random pod and observing recovery.

4. 12

   How do you decide which alerts should page an on-call engineer versus just create a ticket?

   Base it on user impact and urgency, using SLOs and error budgets. Explain that pages should be actionable and rare to avoid alert fatigue.

Behavioural and HR questions

1. 13

   Tell me about a time you had to debug a technical problem under time pressure.

   Use the STAR method and focus on your systematic approach. Highlight communication and what you learned to prevent recurrence.

2. 14

   Are you comfortable being on an on-call rotation, including occasional night or weekend alerts?

   Show willingness and mention strategies for staying calm and following runbooks. Emphasise teamwork and escalation when needed.

3. 15

   Describe a situation where you disagreed with a teammate on a technical solution.

   Focus on data-driven discussion and respectful resolution. Show that you can compromise for the team's goal.

4. 16

   Why do you want to work as an SRE at a global tech company like Imperva India?

   Connect your interest in reliability and security to the company's products and scale. Mention eagerness to learn from large-scale systems without claiming inside knowledge.