50+ Site Reliability Engineer Interview Questions and Answers

Program to find a missing number in Arrays

• Sort the array and iterate to find the missing number

• Use XOR operation to find the missing number

• Calculate the sum of all numbers and subtract from the sum of expected numbers to find the missing number

Script to display logs of GET response and response time and code from a log file

• Use grep command to filter GET requests from the log file

• Use awk command to extract response time and response code from the filtered logs

• Format the output using printf command

• Example: grep 'GET' logfile | awk '{print $4, $9, $NF}' | printf '%-20s %-10s %-10s '

The Collection Framework is a unified architecture for representing and manipulating collections in Java.

• It provides interfaces like List, Set, Queue, etc. for storing and manipulating collections of objects.

• It also provides concrete classes like ArrayList, HashSet, PriorityQueue, etc. that implement these interfaces.

• It supports algorithms like sorting, searching, and shuffling on collections.

• It is a part of the Java Collections Framework.

• Example: List names = new ArrayList<>...read more

I know various Linux commands for file management, process management, networking, and system administration.

• File management: ls, cd, cp, mv, rm, mkdir, touch

• Process management: ps, top, kill, nice, renice

• Networking: ping, traceroute, netstat, ifconfig, ssh

• System administration: sudo, apt-get, systemctl, journalctl, crontab

SLI stands for Service Level Indicator and SLO stands for Service Level Objective. They are used to measure and define the reliability of a service.

• SLI is a metric that measures the performance of a service, such as latency or availability.

• SLO is a target value or range for a specific SLI that defines the acceptable level of reliability for a service.

• Setting up SLI involves defining the metrics to be measured and collecting data to calculate them.

• Using SLO involves setting sp...read more

Jenkins is a CI/CD tool, Shell scripting automates tasks, Cron job schedules tasks, System files store configuration data.

• Jenkins is a popular CI/CD tool used for continuous integration and deployment

• Shell scripting is a way to automate tasks on a Unix/Linux system using command line interface

• Cron job is a scheduling utility in Unix/Linux systems used to schedule tasks at specific times

• System files are configuration files that store system-wide settings and preferences

To monitor intermittent high response, use monitoring tools like Prometheus or Datadog. Troubleshoot by analyzing logs, identifying bottlenecks, and optimizing code.

• Set up monitoring tools like Prometheus or Datadog to track response times

• Analyze logs to identify patterns of high response times

• Use profiling tools to pinpoint bottlenecks in the code

• Optimize code to improve response times

VPC is a virtual private cloud that allows users to create a private network within the public cloud.

• VPC provides a secure and isolated environment for resources in the cloud

• NAT (Network Address Translation) allows instances in a private subnet to access the internet

• Subnets are subdivisions of a VPC that allow users to segment their resources and apply different security policies

Questions on swap memory, projects, CI/CD, Docker, and Kubernetes for Site Reliability Engineer role.

• Swap memory is a space on the hard disk used as virtual memory when RAM is full.

• Projects worked on may include automation, monitoring, and scaling.

• CI/CD is a software development practice that involves continuous integration, testing, and deployment.

• Docker is a containerization platform that allows for easy deployment and management of applications.

• Kubernetes is an open-source...read more

Integrating applications to observability tools like Grafana involves setting up data sources and creating dashboards.

• Configure data sources in Grafana to connect to the application's metrics

• Create custom dashboards in Grafana to visualize the application's performance

• Use Grafana plugins or APIs to enhance monitoring capabilities

An abstract class is a class that cannot be instantiated and is used as a base class for other classes.

• An abstract class can have abstract and non-abstract methods.

• Abstract methods have no implementation and must be implemented by the subclass.

• A class can only extend one abstract class but can implement multiple interfaces.

• Abstract classes are used to provide a common interface for a group of related classes.

• Example: abstract class Animal { abstract void makeSound(); }

It depends on the specific use case and requirements of the project.

• Consider the complexity and scale of the project - Kubernetes is better suited for large, complex applications with multiple services, while Lambda is more suitable for smaller, event-driven applications.

• Evaluate the cost implications - Lambda can be more cost-effective for low-traffic applications due to its pay-per-use pricing model, while Kubernetes may be more cost-effective for high-traffic applications ...read more

Git is a version control system used for tracking changes in code. It allows collaboration and easy management of codebase.

• git init - initializes a new git repository

• git add - adds changes to the staging area

• git commit - commits changes to the repository

• git push - pushes changes to a remote repository

• git pull - pulls changes from a remote repository

• git branch - lists all branches in the repository

• git merge - merges changes from one branch to another

Terraform template to create EC2 instance in AWS

• Define provider and region

• Create security group and define ingress/egress rules

• Define instance type, AMI, key pair, and user data

• Create instance resource and associate with security group

Constructor can be declared static or non-static depending on the use case.

• If a constructor is declared static, it means it can be called without creating an instance of the class.

• Static constructors are used to initialize static fields of the class.

• Non-static constructors are used to initialize instance fields of the class.

• If a class has both static and non-static constructors, the non-static constructor is called when an instance of the class is created.

Design a CI/CD pipeline for an application on EC2 in production ensuring scalability, reliability, and automated testing.

• Use a version control system like Git for managing code changes.

• Set up a CI/CD tool like Jenkins to automate the build, test, and deployment process.

• Implement automated testing at different stages of the pipeline (unit tests, integration tests, etc.).

• Utilize infrastructure as code tools like Terraform to provision and manage EC2 instances.

• Include monitoring...read more

To copy contents of a file to another file, you can use file handling methods in programming languages.

• Open the source file in read mode and the destination file in write mode

• Read the contents of the source file and write them to the destination file

• Close both files after the copying process is complete

Locators are used to identify web elements in Selenium.

• Locators are used to find and interact with web elements on a web page.

• There are several types of locators in Selenium, including ID, name, class name, tag name, link text, and partial link text.

• For example, to find an element with the ID 'username', you would use the ID locator: driver.findElement(By.id('username'));

Code for Fibonacci series in Python

• Define a function that takes an integer as input

• Initialize two variables with 0 and 1 respectively

• Use a for loop to iterate through the range of the input integer

• Add the two variables and assign the result to a third variable

• Print the third variable and update the first two variables

Python program to remove whitespace, check if strings are anagram, and reverse a string.

• Use the replace() function to remove whitespace from a string.

• Use sorted() function to check if two strings are anagrams.

• Use string slicing to reverse a string.

Rollback in deployment tasks is handled by following a structured process to revert to a previous stable version.

• Maintain version control for all deployments

• Automate rollback process to minimize downtime

• Perform thorough testing before deploying to production

• Monitor system health during deployment to detect issues

• Have a rollback plan in place with clear steps and communication channels

• Document and learn from rollback incidents to improve future deployments

Program to reverse a string

• Use a loop to iterate through the string and append each character to a new string in reverse order

• Alternatively, use built-in string reversal functions in some programming languages

A dictionary is a collection of key-value pairs in Python.

• Keys must be unique and immutable.

• Values can be of any data type.

• Dictionaries are mutable and can be modified.

• Access values using keys.

• Use the 'in' keyword to check if a key exists in the dictionary.

To find a one element Xpath in Amazon.com

• Inspect the element in the browser

• Right-click on the element and select 'Copy XPath'

• Use the copied XPath in your code

An explicit constructor is a constructor that is defined with the 'explicit' keyword.

• It is used to prevent implicit conversions from the constructor's parameter type to the class type.

• It requires the constructor to be called explicitly with the class name and constructor arguments.

• It is commonly used to avoid unexpected type conversions and improve code clarity.

To merge particular commits to a branch, use git cherry-pick command.

• Identify the commit hash of the specific commit you want to merge

• Switch to the branch where you want to merge the commit

• Use 'git cherry-pick ' to apply the changes of that commit to the current branch

Use 'find' command to fetch larger files in specific directory

• Use 'find' command with '-size' option to specify file size

• Example: find /path/to/directory -type f -size +100M

An interface in Java is a collection of abstract methods and constants that can be implemented by a class.

• An interface is declared using the interface keyword.

• It can be implemented by any class using the implements keyword.

• All methods in an interface are implicitly public and abstract.

• Interfaces can also contain constants, which are implicitly public, static, and final.

• Interfaces are used to achieve abstraction and provide a way for unrelated classes to communicate with each ...read more

Ansible playbook to install and configure Apache web server

• Install Apache package using apt or yum module

• Copy configuration files using copy module

• Start and enable Apache service using service module

I systematically gather information, analyze logs, consult documentation, and test hypotheses to identify and resolve the error.

• Gather information about the error: check logs, error messages, and user reports.

• Consult documentation and resources related to the technology or system in question.

• Isolate the issue by testing different components or configurations.

• Formulate hypotheses based on gathered information and test them to identify the root cause.

• Collaborate with team membe...read more

Relative XPath is a way to locate elements in XML or HTML documents based on their position relative to other elements.

• Relative XPath uses the relationships between elements to navigate the document structure.

• It is more flexible than absolute XPath as it adapts to changes in the document's structure.

• Relative XPath expressions start with a reference to an element and then use various axes and predicates to locate the desired element.

• Example: //div[@class='container']/a[2] sele...read more

Selenium automation can control Chrome browser capabilities such as handling pop-ups, cookies, and browser settings.

• Selenium can handle pop-ups and alerts using the switchTo() method

• Cookies can be managed using the addCookie() and deleteCookie() methods

• Browser settings can be modified using the ChromeOptions class

• Examples: disabling images, setting the browser window size, and using headless mode

HPA stands for Horizontal Pod Autoscaler in Kubernetes.

• HPA automatically scales the number of pods in a deployment based on CPU utilization or other custom metrics.

• It ensures that the application is always available and can handle increased traffic.

• HPA can be configured using YAML files or through the Kubernetes API.

• Example: kubectl autoscale deployment my-deployment --cpu-percent=50 --min=1 --max=10

• HPA can also be used with custom metrics provided by Prometheus or other moni...read more

Self join is a SQL query that joins a table with itself.

• Use the table name twice in the query, with different aliases

• Specify the columns to be selected from each table

• Specify the join condition using the aliases

• Example: SELECT a.column1, b.column2 FROM table a JOIN table b ON a.column3 = b.column4

Implement rolling updates and blue-green deployments to apply security patches with minimal downtime.

• Utilize rolling updates to gradually apply security patches to different instances without taking the entire system offline.

• Implement blue-green deployments to switch traffic from the old version (blue) to the new version (green) seamlessly.

• Use automation tools like Ansible, Puppet, or Chef to streamline the patching process and reduce human error.

• Perform thorough testing in a...read more

Command to list CPUs in Linux system

• Use the 'lscpu' command to list detailed information about CPUs

• Use the 'nproc' command to display the number of processing units available

• Use the 'cat /proc/cpuinfo' command to view information about each CPU core

Designing a TCP server using TCP sockets and sys calls

• Create a socket using socket() system call

• Bind the socket to an address and port using bind() system call

• Listen for incoming connections using listen() system call

• Accept incoming connections using accept() system call

• Communicate with clients using read() and write() system calls

List of 25 commonly used Linux commands

• ls - list directory contents

• cd - change directory

• pwd - print working directory

• mkdir - make directory

• rm - remove files or directories

• cp - copy files or directories

• mv - move or rename files or directories

• cat - concatenate and display files

• grep - search for a pattern in a file

• find - search for files in a directory hierarchy

• chmod - change file mode bits

• chown - change file owner and group

• ps - report a snapshot of the current processes

• kill - s...read more

We handle the infrastructure by using automation, monitoring, and scalability.

• Utilize automation tools like Terraform or Ansible to provision and manage infrastructure.

• Implement monitoring solutions like Prometheus or Grafana to track system performance and health.

• Design infrastructure to be scalable and resilient to handle varying workloads.

• Regularly review and update infrastructure to ensure security and efficiency.

• Collaborate with cross-functional teams to align infrastruc...read more

Design a cloud architecture for a 3-tier application

• Use load balancers to distribute traffic across multiple instances

• Deploy application servers in multiple availability zones for high availability

• Use a managed database service for the database tier

• Implement auto-scaling to handle varying traffic loads

• Use a content delivery network (CDN) for static assets

• Implement monitoring and alerting to detect and respond to issues

• Ensure security by using encryption, firewalls, and access...read more

CloudWatch is a monitoring service for AWS resources. Jira is a project management tool.

• CloudWatch is used to collect and track metrics, collect and monitor log files, and set alarms.

• Jira is used for issue tracking, bug tracking, and project management.

• CloudWatch can be used to monitor EC2 instances, RDS DB instances, and Elastic Load Balancers.

• Jira can be used to manage software development projects, track bugs and issues, and collaborate with team members.

Liveness probe in K8s is used to determine if a container is running properly by checking if it is responsive.

• Liveness probes are configured in Kubernetes to periodically check the health of a container.

• If the liveness probe fails, Kubernetes will restart the container.

• Common liveness probe types include HTTP, TCP, and Exec probes.

• Example: A HTTP liveness probe can check if a web server within a container is responding with a 200 status code.

Command to check free disk space

• Use the 'df' command to check free disk space

• The '-h' option displays the output in human-readable format

• The '-T' option shows the filesystem type

• The '-x' option excludes specific filesystem types

• The '-t' option filters the output based on filesystem type

Command to check free memory space

• Use the 'free' command to check free memory space

• The 'free' command displays the total, used, and free memory space in the system

• It also shows the amount of memory used for buffers and cache

• The 'free' command can be used with options like '-h' for human-readable output

NoSQL is a non-relational database that provides flexible schema and horizontal scalability, while SQL is a relational database with structured schema and vertical scalability.

• NoSQL databases are schema-less and can handle unstructured data.

• SQL databases use structured query language and have predefined schemas.

• NoSQL databases are horizontally scalable, allowing for easy distribution of data across multiple servers.

• SQL databases are vertically scalable, meaning they can handl...read more

Apache is a web server while Nagios is a monitoring tool.

• Apache is used to serve web pages and applications.

• Nagios is used to monitor the health and performance of servers, applications, and services.

• Apache can be used with Nagios to monitor web servers and applications.

• Apache is open source and widely used, while Nagios is also open source but less popular.

To copy files to a remote machine, use a file transfer protocol like SCP or SFTP.

• Use SCP (Secure Copy) command to copy files between local and remote machines

• Example: scp /path/to/local/file username@remote:/path/to/destination

• Use SFTP (Secure File Transfer Protocol) for interactive file transfers

• Example: sftp username@remote, then use put command to upload files