Bill.com India Site Reliability Engineer Interview: Rounds, Questions and Preparation

What the job involves

Site Reliability Engineers at global tech companies like Bill.com India ensure that large-scale payment and financial platforms remain highly available, performant, and secure. Day to day, they build automation for deployment and monitoring, respond to incidents, and use data to improve system reliability. Freshers in this role typically start with observability tasks, runbook automation, and on-call shadowing.

Role and Technical Knowledge

1. 1

   What is the difference between a Site Reliability Engineer and a DevOps Engineer?

   Explain that SRE applies software engineering to operations with a focus on reliability metrics like SLOs, while DevOps is a broader cultural movement. Mention shared ownership and automation.

2. 2

   How would you explain SLI, SLO, and SLA to a non-technical product manager?

   Use simple analogies: SLI is a measurement (e.g., request latency), SLO is an internal target (e.g., 99.9% under 200ms), SLA is a contract with penalties. Emphasise that SLOs drive engineering decisions.

3. 3

   A payment service has 99.9% uptime. How many minutes of downtime is that per month, and why does it matter for a fintech company?

   Calculate 0.1% of 30 days = about 43 minutes. Explain that for payment platforms, downtime can mean failed transactions, lost revenue, and regulatory issues, so even small outages are costly.

4. 4

   What is the difference between a blue-green deployment and a canary deployment?

   Blue-green switches all traffic at once between two identical environments; canary routes a small percentage of traffic to the new version first. Mention rollback speed and risk reduction.

Practical Scenarios

1. 5

   You get an alert that a payment API is returning 500 errors for 10% of requests. Walk me through your troubleshooting steps.

   Start by checking dashboards for error rates, logs, and recent deployments. Then isolate whether it is a code bug, database issue, or dependency failure. Communicate status and roll back if needed.

2. 6

   How would you automate the process of restarting a service that frequently runs out of memory?

   Suggest a script or Kubernetes liveness probe that monitors memory and restarts the pod. Also mention investigating the root cause like a memory leak rather than just restarting.

3. 7

   You need to reduce alert noise for a service that sends 100 alerts per day, most of which are non-actionable. What do you do?

   Propose grouping related alerts, adjusting thresholds based on SLOs, and using alert suppression during maintenance. Emphasise focusing on symptoms that impact users.

4. 8

   A database is experiencing high read latency during peak hours. How would you diagnose and mitigate it?

   Check slow query logs, indexes, and connection pool usage. Mitigate with caching, read replicas, or query optimisation. Mention monitoring tools like Prometheus or Datadog.

Behavioural and Teamwork

1. 9

   Tell me about a time you had to debug a problem under time pressure. How did you handle it?

   Use STAR method: describe the situation, your systematic approach, how you communicated, and the outcome. Highlight staying calm and prioritising user impact.

2. 10

   Describe a situation where you disagreed with a teammate on a technical solution. How did you resolve it?

   Show that you listen, use data to support your view, and are willing to compromise for the team's goal. Avoid blaming others.

3. 11

   How would you handle being on-call for the first time and getting a critical alert at 2 AM?

   Explain that you would follow the runbook, escalate if unsure, and document the incident. Emphasise that it is okay to ask for help and that postmortems are blameless.

4. 12

   Give an example of a time you automated a repetitive task. What was the impact?

   Describe the task, the script or tool you used, and the time saved or errors reduced. Connect it to reliability and efficiency.

HR and Company Fit

1. 13

   Why do you want to work as a Site Reliability Engineer at a fintech company like Bill.com India?

   Show interest in high-scale, high-availability systems and the fintech domain. Mention specific aspects like payment reliability, compliance, or automation. Avoid generic answers.

2. 14

   Where do you see yourself in three years in an SRE career path?

   Talk about growing from junior SRE to owning services, mentoring, and contributing to reliability strategy. Show enthusiasm for learning cloud and automation technologies.

3. 15

   How do you keep your technical skills updated outside of college?

   Mention personal projects, online labs, open-source contributions, or certifications. Relate them to SRE skills like Kubernetes, monitoring, or scripting.

4. 16

   Are you comfortable with on-call rotations and working in a 24/7 environment?

   Answer honestly and positively. Explain that you understand the responsibility, are willing to learn, and value the team support and processes that make on-call manageable.