Top 50 Site Reliability Engineer Interview Questions & Answers

With the rapid advancement in technology, the importance of Site reliability engineering in modern systems is at a premium. It creates a bridge between operations and coding departments, maintaining the ever-necessary performance and reliability.

With the impact of technology that we are in today, businesses need to have systems in place. The ability to work and execute tasks without interruptions and hitches becomes a priority for organisations.

In this article, we will address the most frequently asked site reliability engineer interview questions for freshers and experienced. The most basic and the most advanced practices shall be addressed to aid you prepare more effectively.

Introduction to Site Reliability Engineer Job Role

Site Reliability Engineering (SRE) brought about a set of practices that have become critical for the development of large integrated systems to work efficiently and consistently. It combines software development practices and IT operation, emphasising automation and reliability over manual processes. High-quality reliability, availability, and incident management are three key areas where SREs seek to excel in today’s increasingly complex technological environment.

Why Site Reliability Engineers Are Important

• For most companies, reliability is of paramount concern. In the online world where most businesses operate, downtime could result in devastating consequences both in terms of revenue and brand image. SRE’s mission is to keep the systems running.
• Working alongside development and operations is not the passion of most people, but at the same time, SREs understand the two areas closely. They enhance the collaboration between development and operations teams.
• As SREs streamline processes through the use of automation, it cuts down on the amount of time spent on repetitive tasks, thus creating room for quicker as well as more efficient procedures.

Core Responsibilities of SREs

• Monitoring and response to an incident: Due to the use of monitoring tools embedded with SRE-style practices, most issues are preempted from reaching the users. They also engage themselves in the rapid resolution of incidents.
• Performance and workload management: Ensuring systems run efficiently under varying workloads is a key focus area.
• Building Systems that are Fault-Tolerant: In the event of a fault, which is unavoidable, they always build systems using failover and redirection techniques.
• Management of service levels: SREs define and monitor Service Level Objectives (SLOs) and Service Level Agreements (SLAs) to maintain user satisfaction.

Key Skills for SREs

• Programming and Scripting: To carry out bug fixes and automation of scripts, some proficiency in Python, Go or similar is an important requirement.
• Cloud and Containerization: It is important to know the platforms like AWS, Kubernetes, or Docker.
• Monitoring applications: Knowledge of the workings of applications, such as Prometheus, Datadog, and Grafana.
• Management Of An Incident: An understanding of the chronicling of logs and some high-stress moments can be excellent for such a role.

Why SRE Is a Promising Career Path

• High demand in most sectors, such as finance, healthcare and technology.
• Good salaries and career growth.
• Working with the latest technologies and coming up with solutions to real-life scenarios.

Understanding the basic concepts of SREs prepares you to tackle what will be expected in most interviews and how to go about excelling in the activities of this fast-changing environment.

1. What Is DevOps?

DevOps is described simply as a connecting activity between development and IT operations. It emphasises teamwork, integration, and continuous deployment throughout the stages of the software development lifecycle.

Core DevOps principles include:

• Automation: Lowers the need for human interference and reduces the time required to deploy.
• Continuous Integration and Delivery (CI/CD): This provides timely and steady improvements.
• Monitoring and Feedback: Provides qualitative insights that provide improvement opportunities for the system.

2. What Is the Transmission Control Protocol (TCP)?

Transmission control protocol is a network communication protocol which is connection-oriented. It allows secure sharing of information over a network by creating a connection between two devices and guarantees transmission of data.

Key features of TCP:

• Reliable Communication: Ensures no data is lost or duplicated.
• Error Checking: Verifies integrity of transmitted data.
• Ordered Data Delivery: Maintains sequence for proper reconstruction.

3. Explain the Differences Between TCP and UDP

4. Explain DNS and Its Importance.

DNS, or Domain Name System, translates human-readable domain names (e.g., www.example.com) into IP addresses understood by machines. It acts as the internet’s address book.

Importance of DNS:

• Ease of Use: Allows users to access websites without memorising IP addresses.
• Scalability: Handles billions of requests daily, enabling smooth internet browsing.
• Fault Tolerance: Ensures redundancy for uninterrupted service.

5. Define Hardlink and Softlink.

Hardlinks and softlinks are methods to reference files in a file system.

• Hardlink: A direct reference to the file’s data on disk. Deleting the original file does not affect the hardlink.
• Softlink (Symbolic Link): A shortcut pointing to the file path. Deleting the original file breaks the softlink.

Key differences:

6. What Are the States In Which the Process Could be Implemented?

A process in an operating system transitions through different states during its execution.

• New: Process is being created.
• Ready: The process is ready to execute, waiting for CPU time.
• Running: The process actively executes instructions on the CPU.
• Waiting: The process is waiting for an external event or resource.
• Terminated: The process has completed execution or has been stopped.

Understanding process states helps in effective resource management.

7. What Is Cloud Computing?

Cloud computing allows instant access to online major computing facilities such as servers, applications and storage. There is no necessity for any physical devices.

Benefits of cloud computing:

• Scalability: Resources can be scaled up or down as needed.
• Cost savings: The cost of hardware upkeep is reduced.
• Convenience and flexibility: Internet connectivity allows for access to information from anywhere.

Known providers of cloud services are AWS, Azure and Google Cloud.

8. What Is DHCP, and for What Is It Used?

DHCP (Dynamic Host Configuration Protocol) is a network management protocol. It automatically assigns IP addresses and other network configurations to devices in a network.

Uses of DHCP:

• Simplifies Management: Eliminates the need for manual IP address assignment.
• Prevents Conflicts: Ensures unique IP addresses are allocated.
• Dynamic Allocation: Supports temporary address assignments for devices.

9. Explain the Concept of Service Level Objective (SLO).

A Service Level Objective (SLO) is a measurable goal for system performance or reliability. It defines the acceptable level of service based on metrics like uptime, latency, or error rate.

For example:

• SLO for Uptime:9% availability over a month.
• SLO for Response Time: API latency below 200 ms for 95% of requests.

SLOs are critical for maintaining user satisfaction and aligning team priorities.

10. What Is an Error Budget?

An error budget represents the allowable margin of failure within an SLO. It balances reliability and innovation by setting limits for system downtime or errors.

For example:

• If the SLO is 99.9% uptime, the error budget allows for 0.1% downtime.
• Teams can use this budget to deploy changes and test improvements without compromising reliability.

11. Explain the Difference Between Proactive and Reactive Monitoring.

12. How Do You Prioritise Tasks and Incidents in SRE?

Prioritising tasks and incidents requires balancing urgency and impact:

• Assess Impact: Prioritise incidents affecting critical systems or users.
• Categorise Urgency: Address high-severity incidents (e.g., outages) first.
• Follow SLAs/SLOs: Resolve tasks based on defined service agreements.
• Use Incident Management Tools: Tools like PagerDuty or Jira help organise and track priorities.

Effective prioritisation ensures smooth operations and timely issue resolution.

13. What Is a Runbook?

A runbook is a documented procedure for handling specific incidents or tasks. It acts as a guide for system administrators and engineers.

Key features of a runbook:

• Step-by-Step Instructions: Details actions to resolve incidents.
• Automation Scripts: Includes scripts for repetitive tasks.
• Common Use Cases: System recovery, deploying updates, or handling alerts.

14. What Is Chaos Engineering?

Chaos engineering is the practice of intentionally introducing failures into a system to test its resilience. The goal is to identify weaknesses and improve fault tolerance.

Key aspects:

• Failure Injection: Simulating outages, latency spikes, or resource exhaustion.
• Observing Impact: Measuring system response under stress.
• Strengthening Systems: Addressing vulnerabilities before they impact users.

Popular tools for chaos engineering include Gremlin and Chaos Monkey.

15. What Are Some Databases You’ve Used in the Past?

Databases commonly used in SRE include:

• Relational Databases: MySQL, PostgreSQL for structured data with SQL support.
• NoSQL Databases: MongoDB, Cassandra for handling unstructured or distributed data.
• Key-Value Stores: Redis, DynamoDB for fast, scalable key-value storage.
• Time-Series Databases: Prometheus, InfluxDB for monitoring and storing metrics.

Choosing the right database depends on the specific use case and system requirements.

16. Explain the Difference Between fork() and exec().

17. What Is Swap Memory?

Swap memory is a portion of disk space used as virtual memory when physical RAM is full. It acts as an overflow area, ensuring system stability under heavy load.

Key points about swap memory:

• Prevents Crashes: Allows processes to continue running when RAM is insufficient.
• Slower than RAM: Disk access is slower, so excessive swapping can degrade performance.
• Configured by OS: Swap size and usage depend on the operating system settings.

18. What Is Virtual Memory?

Virtual memory is a memory management technique that allows a computer to use more memory than is physically available. It creates an illusion of a large, contiguous memory space by using both RAM and disk storage.

Key features:

• Memory Extension: Expands available memory by swapping data between RAM and disk.
• Isolates Processes: Ensures each process operates in its own virtual address space.

19. What Is the Difference Between a Process and a Thread?

20. What Is Docker?

Docker is a platform that enables developers to package applications and their dependencies into containers. These containers ensure consistency across development, testing, and production environments.

Advantages of Docker:

• Portability: Containers can run anywhere, regardless of the host environment.
• Resource Efficiency: Lightweight compared to virtual machines.
• Isolation: Each container operates independently, avoiding conflicts.

21. What Is the Difference Between Stateful and Stateless Applications?

22. What Is the Role of Version Control in SRE?

Version control is essential in SRE for managing changes to code, configurations, and infrastructure. It ensures traceability, collaboration, and rollback capabilities.

Key roles:

• Change Tracking: Logs every modification for transparency.
• Collaboration: Enables teams to work on the same project without conflicts.
• Incident Recovery: Facilitates rollbacks to a stable state during failures.

23. What Is Consistent Hashing?

Consistent hashing is a distributed system technique to evenly distribute data across servers or nodes. It minimises data redistribution when nodes are added or removed.

Key benefits:

• Scalability: Handles dynamic system growth with minimal overhead.
• Load Balancing: Ensures even distribution of data.
• Fault Tolerance: Reduces the impact of node failures.

24. What Does Virtualization Mean?

Virtualization is the process of creating virtual versions of physical hardware, such as servers, storage, or networks. It allows multiple virtual environments to run on a single physical machine.

Key advantages:

• Resource Efficiency: Maximises hardware utilisation.
• Isolation: Ensures each virtual environment is independent.
• Flexibility: Supports diverse operating systems and applications on the same machine.

25. What Are Containers in Servers?

Containers are lightweight environments that package applications and their dependencies. They share the host system’s OS kernel but run in isolated spaces.

Key features:

• Portability: Consistent behaviour across different environments.
• Isolation: Keeps applications separate to avoid conflicts.
• Efficiency: Uses fewer resources compared to virtual machines.

26. What Is the Difference Between Synchronous and Asynchronous Communication in Distributed Systems?

SRE Interview Questions for Experienced

27. What is Sharding in DBMS?

Sharding is a database partitioning technique that splits data across multiple databases or servers horizontally. Every shard includes a subset of all the data.

Key benefits:

• Scalability: Distributes data to handle large volumes.
• Performance: Reduces load on individual servers, improving query times.
• Fault Tolerance: Isolated shards minimise the impact of server failures.

28. Why Do We Use the Concept of Private IPs and Public IPs?

Private and public IPs separate internal and external network communications:

Private IPs:

• Used within local networks.
• Not accessible from the internet.
• Enhance security by isolating internal resources.

Public IPs:

• Used for devices accessible over the internet.
• Allow external communication, such as hosting websites or services.
• This separation ensures security and efficient use of IP addresses.

29. Explain the Difference Between SNAT and DNAT.

30. What is 2FA?

2FA (Two-Factor Authentication) is a security mechanism requiring two forms of verification to access a system. It strengthens account protection by combining:

• Something You Know: A password or PIN.
• Something You Have: A smartphone, token, or physical key.

This method reduces the risk of unauthorised access, even if one factor is compromised.

31. What Is Multithreading in an Operating System?

Multithreading allows a process to execute multiple threads concurrently. Each thread operates independently but shares the process’s memory and resources.

Advantages:

• Improved Performance: Utilises CPU cores efficiently.
• Resource Sharing: Threads within a process communicate faster than separate processes.

Also Read: Multithreading in Java

32. What Is Suspended Ready?

The suspended ready state occurs when a process is moved to secondary storage but is ready for execution. It waits for the operating system to bring it back to the main memory.

Reasons for suspension:

• Resource Availability: Freeing up RAM for higher-priority processes.
• Power Management: Pausing inactive processes to conserve energy.

33. What Are the Types of Proc?

Proc refers to processes in Unix/Linux systems, and they are categorised into:

• Foreground Processes: Run in the shell and require user interaction.
• Background Processes: Run without user interaction and do not block the terminal.
• Daemon Processes: When you find these processes, you can see they run for an extensive period. They perform background jobs like logging or monitoring.

34. SRE vs DevOps: What’s the Difference Between Them?

35. What Is the Kill Command in Linux?

This command in Linux kills the process of sending signals. It sends a SIGTERM signal by default to politely ask the process to stop.

Common usage:

• Syntax: kill [signal] PID

Examples:

• kill -9 PID sends the SIGKILL signal to force termination.
• kill -15 PID sends the default SIGTERM signal for graceful termination.

This command is essential for managing unresponsive or rogue processes.

36. How May OOPs Be Used When Creating a Server?

Object-Oriented Programming (OOP) encapsulates related behaviours and data in a structured form for designing server applications.

• Encapsulation: Classes can represent server components, like Request, Response, or DatabaseConnection, ensuring modularity.
• Inheritance: Shared functionalities, such as HTTPServer or WebSocketServer, can inherit common behaviours from a parent class.
• Polymorphism: Enables flexibility by defining how different types of requests (e.g., GET, POST) are handled through method overriding.

OOP principles ensure reusable, maintainable, and scalable server design.

37. What Do You Mean by SLO?

You can take the help of a Service Level Objective (SLO) to measure performance goals, which will define the standard for any service. This is a part of the Service Level Agreement.

Examples:

• Uptime SLO: Service should be available 99.9% of the time.
• Latency SLO: The response should be below 200 ms for 95% of requests.

SLOs guide teams to focus their efforts on user expectations and business needs.

38. What Is a Service-Level Agreement?

A Service Level Agreement is the documented contract between the service provider and the users. It includes agreed-upon performance metrics and the consequences of missing them.

Key components of SLA:

• Uptime Guarantee: Minimum availability, e.g., 99.5%.
• Response Times: Time to resolve incidents or respond to support queries.
• Penalties: Compensation for unmet commitments.

SLAs define clear expectations and accountability with regard to service quality.

39. What Is the Difference Between an API Gateway and a Reverse Proxy?

40. What Is a Service Level Indicator?

This is used when you have to measure the performance of the service against a specific aspect of an SLO.

Examples of SLIs:

• Latency: Average response time of a service.
• Availability: Percentage uptime over a given period.
• Error Rate: Percentage of failed requests.

SLIs provide quantitative data, so it becomes possible to judge whether SLOs are being met.

41. How Do You Measure and Improve System Reliability?

Measuring System Reliability:

• Key Metrics: Uptime, mean time between failures (MTBF), mean time to recovery (MTTR), and error rates.
• Tools: Monitoring tools like Prometheus, Grafana, or Datadog.

Improving Reliability:

• Redundancy: Use failover systems and backups.
• Proactive Monitoring: Detects issues before they impact users.
• Automation: Reduce human errors with automated deployments and testing.

Regular reviews and resilience testing help maintain reliability.

42. What Is Microservices Architecture?

Microservices architecture is a style of designing an application or multiple applications as separate, small services that focus on providing specific narrow functionalities communicated between services using APIs.

Key features:

• Independence: Services can be developed, deployed, and scaled independently.
• Fault Isolation: Failure in one service doesn’t impact the entire application.
• Scalability: Allows scaling of individual components based on demand.

Popular examples include services in e-commerce platforms like order management or payment processing.

43. What Is a Playbook, and How Is It Different from a Runbook?

Example: A playbook outlines how to respond to a major outage, while a runbook provides commands to restart the database.

44. How Do You Manage Configuration Drift?

Configuration drift occurs when system configurations deviate from their intended state over time. Managing it involves:

• Automation: Use tools like Ansible, Puppet, or Terraform to enforce desired configurations.
• Version Control: Track configuration files in a version control system like Git.
• Monitoring: Implement drift detection tools to identify changes early.

Regular audits and automated remediation keep systems consistent and reliable.

45. What Is a Service Mesh?

Suppose you have to manage a service-to-service communication within a microsystems architecture. This is where a service mesh is used, which brings you a managing infrastructure, and you can also perform operations like Routing, load balancing, service discovery, and security along with the service mesh.

Key features:

• Traffic Management: Controls request routing between services.
• Observability: Provides metrics and logs for monitoring.
• Security: Enables encryption and authentication between services.

Popular tools include Istio, Linkerd, and Consul.

46. How Do You Secure Cloud Environments and Manage Access Control?

Securing cloud environments involves multiple strategies:

Access Control:

• Use role-based access control (RBAC) to restrict user permissions.
• Implement multi-factor authentication (MFA) for added security.

Network Security:

• Use virtual private clouds (VPCs) and firewalls to isolate resources.
• Encrypt data in transit and at rest.
• Monitoring and Auditing:
• Regularly review logs and detect unauthorised access.

Automation tools like AWS IAM and Azure Security Center streamline these tasks.

47. Explain the Difference Between Horizontal and Vertical Scaling.

48. Explain How You Would Migrate an On-Premise Application to the Cloud.

Migrating an on-premise application to the cloud involves several steps:

Assessment and Planning:

• Evaluate the application’s compatibility with cloud platforms.
• Identify resources and dependencies.

Choosing the Right Cloud Model:

• Decide between IaaS, PaaS, or SaaS based on requirements.
• Data and Application Migration:
• Transfer databases and application files using tools like AWS Migration Hub or Azure Migrate.

Testing and Optimization:

• Validate application functionality in the cloud.
• Optimise performance for cloud environments.

Cutover:

• Switch users from on-premise to the cloud system gradually or in phases.

49. How Do You Determine Which Metrics Are Important for an Application’s Performance?

To identify critical performance metrics:

Understand the Application’s Goals:

• Define key performance indicators (KPIs) like uptime, response time, or error rate.

User Impact:

• Focus on metrics that directly affect the user experience, such as latency or throughput.

System Performance:

• Monitor CPU, memory usage, and disk I/O in order to ensure efficient utilisation of resources.

Such metrics can be tracked and analysed properly by tools like Prometheus or Datadog.

50. How Do You Ensure That Alerts Are Actionable and Not Overwhelming?

To make alerts actionable:

• Set Clear Thresholds: Define alert thresholds based on SLOs to avoid unnecessary notifications.
• Prioritise Alerts: Categorise them by severity (e.g., critical, warning).
• Reduce Noise: Use aggregated alerts to group similar incidents.
• Review Alerts Regularly: Update and tune alert policies to match current requirements.

Implementing these practices ensures meaningful notifications without overwhelming the team.

51. Define Service Level Indicators (SLIs).

SLIs are measurable metrics that describe the performance of a service against certain criteria.

Examples:

• Availability: Percentage of uptime over a given period.
• Latency: Time taken to respond to user requests.
• Error Rate: Percentage of failed requests.

SLIs form the basis for defining SLOs and monitoring service reliability.

52. What Is the Difference Between Scalability and Elasticity?

Conclusion

Site Reliability Engineering (SRE) is the heart of developing reliable, scalable, and efficient systems in today’s high-tech age. If you are a beginner, it may be tough initially for you to understand every feature of Site Reliability Engineering. However, key concepts need to be memorised, and questions related to common interviews must be prepared for an excellent reputation in this dynamic field.

This blog has covered an exhaustive list of SRE interview questions, from definitions to more advanced topics like scalability, SLIs, and cloud migrations. Read through the questions and answers to be more than prepared to show your technical depth and problem-solving acumen at your next SRE interview. Learn more about SRE and DevOps with this Certificate Program in DevOps & Cloud Engineering With Microsoft by Hero Vired and get certified.