90+ Staff Engineer Interview Questions and Answers

Writing accessible HTML code for disabled persons

• Use semantic HTML tags to provide structure and meaning to the content

• Include alternative text for images and other non-text content

• Ensure color contrast meets accessibility standards

• Provide keyboard navigation and focus styles for interactive elements

• Use ARIA attributes to enhance accessibility for dynamic content

• Test with screen readers and other assistive technologies

• Consider using accessible frameworks and libraries

• Provide ...read more

WebDriver supports two types of waits: implicit and explicit.

• Implicit wait: waits for a certain amount of time before throwing a NoSuchElementException if the element is not found

• Explicit wait: waits for a certain condition to occur before proceeding to the next step

• Examples of conditions for explicit wait: element to be clickable, element to be visible, element to have a certain text

• WebDriverWait class is used for explicit wait

Given n seats and m people seated randomly, find the minimum number of hops to seat them together.

• Find all possible contiguous groups of m seats

• Calculate the number of hops required to move each group to the center seat of that group

• Return the minimum number of hops required

Before building reports, I conduct data analysis by following a structured process.

• Define the objective of the analysis and the key questions to be answered

• Collect relevant data from various sources

• Clean and preprocess the data to ensure accuracy and consistency

• Perform exploratory data analysis to identify patterns and trends

• Use statistical methods and tools to analyze the data

• Visualize the data using charts, graphs, and other visualizations

• Interpret the results and draw acti...read more

Simulate Write-Back Cache using two python dictionaries with dirty bit and LRU flushing technique.

• Create two dictionaries, one for cache data and one for dirty bit tracking.

• Implement LRU flushing technique to remove least recently used data when cache is full.

• Set dirty bit to mark data that has been modified and needs to be written back to main memory.

• Update dirty bit when data is modified and track which data needs to be written back.

• Flush dirty data back to main memory when...read more

IP packet header fields and their usage

• Version: indicates the IP version being used (IPv4 or IPv6)

• Header Length: specifies the length of the IP header

• Type of Service: used to prioritize packets

• Total Length: specifies the total length of the IP packet

• Identification: used to identify fragments of a larger packet

• Flags: used to control fragmentation

• Fragment Offset: used to reassemble fragmented packets

• Time to Live: specifies the maximum number of hops a packet can take

• Protocol: s...read more

To clock domain cross a signal with different clock ratios, use a synchronizer circuit with multiple stages.

• Implement a synchronizer circuit with multiple flip-flops to synchronize the signal between different clock domains.

• Use a gray code or other encoding techniques to handle the different clock ratios.

• Ensure proper setup and hold times are met for reliable data transfer.

• Consider using FIFOs or handshaking protocols to handle potential data rate mismatches.

• Perform thorough ...read more

TCP packet header fields and their usage

• TCP packet header consists of 20 bytes

• Fields include source and destination ports, sequence and acknowledgement numbers, flags, window size, and checksum

• Source and destination ports identify the endpoints of the connection

• Sequence and acknowledgement numbers are used for reliable data transfer

• Flags indicate the purpose of the packet, such as SYN, ACK, FIN, RST

• Window size is used for flow control

• Checksum is used for error detection

Migrating VMware server to Azure involves planning, preparation, and execution of the migration process.

• Assess current VMware environment to determine resources and dependencies

• Create a migration plan outlining steps, timeline, and potential risks

• Prepare Azure environment by setting up necessary resources and configurations

• Use Azure Site Recovery or Azure Migrate tool for migration

• Test the migration process in a non-production environment before executing in production

• Monitor...read more

Program in javascript to display a pyramid

• Use nested loops to print the pyramid

• The outer loop controls the number of rows

• The inner loop controls the number of spaces and asterisks to print

• Use string concatenation to build the pyramid

Golang program for CRUDD operations on user details

• Use structs to define user details

• Implement functions for Create, Read, Update, Delete operations

• Use a map or slice to store user data

• Handle errors and input validation

• Use packages like 'fmt' and 'bufio' for input/output operations

Design a distributed log storage and analysis system

• Use a distributed file system like HDFS or Amazon S3 for storing logs

• Implement a log aggregation system like Apache Kafka for collecting logs from various sources

• Utilize a distributed processing framework like Apache Spark for analyzing logs in real-time

• Consider using a NoSQL database like Cassandra for storing processed log data

Develop a rate limiter to limit http connections for a domain in the last 5 minutes

• Use a sliding window algorithm to track the number of connections in the last 5 minutes

• Maintain a data structure to store timestamps of each connection

• Increment the count of connections for a domain and remove outdated timestamps

• Reject connections if the count exceeds the threshold

Finding shortest path to reach a word using modification of edit distance problem

• Use dynamic programming approach

• Create a matrix to store the distances

• Consider all possible operations - insertion, deletion, substitution

• Return the minimum distance to reach the target word

Security is important in a system to protect against unauthorized access, data breaches, and cyber attacks.

• Prevents unauthorized access to sensitive data

• Protects against data breaches and cyber attacks

• Ensures confidentiality, integrity, and availability of data

• Compliance with regulations and standards

• Maintains trust and confidence of customers and stakeholders

Program to sort an array

• Choose a sorting algorithm based on the requirements

• Implement the chosen algorithm in the programming language of choice

• Test the program with different input sizes and edge cases

I will design a scalable and modular architecture that meets the product requirements.

• Identify the key components and their interactions

• Consider scalability and performance requirements

• Use design patterns like MVC or microservices

• Ensure security and data privacy measures are in place

• Document the architecture for future reference

List all containers with max usage of the special tag 'container'.

• Identify all containers with the special tag 'container'.

• Calculate the usage of each container.

• Find the container(s) with the maximum usage.

Design a system similar to Zookeeper for managing distributed systems

• Use a centralized service for maintaining configuration information, naming, and providing distributed synchronization

• Implement a hierarchical namespace similar to file system paths for organizing data

• Utilize a consensus algorithm like Paxos or Raft for ensuring consistency and fault tolerance

Remove duplicates from 2D array of strings

• Use nested loops to compare each element

• Create a new array to store unique strings

• Use HashSet to remove duplicates

Design a routing table with insert, delete, and forward functionality in a defined class.

• Create a class called RoutingTable with methods for insert, delete, and forward

• Use a data structure like a hash table or tree to store routing information

• Implement insert method to add new routes, delete method to remove routes, and forward method to look up and forward packets

Downtime refers to the period when a system or machine is not operational. Mass production is the manufacturing of large quantities of a product.

• Downtime is the time when a system or machine is not working or is undergoing maintenance.

• Mass production is the process of manufacturing a large number of identical products.

• Downtime can be caused by various factors such as equipment failure, power outages, or scheduled maintenance.

• Mass production is often used in industries such as...read more

Implement a method to return total usage

• Create a method that calculates the total usage by summing up individual usage values

• Ensure the method can handle different types of usage data (e.g. integers, floats)

• Consider implementing error handling for invalid input data

• Test the method with sample data to verify its accuracy

BMC stands for Block Formatting Context in CSS, which is a mechanism for controlling the layout of elements.

• BMC is created when an element is floated, positioned absolutely, or has an overflow value other than visible.

• BMC prevents margin collapsing between parent and child elements.

• BMC can be used to create columns of equal height.

• Example: Using display: inline-block on child elements creates a BMC.

• Example: Using overflow: hidden on a parent element creates a BMC.

Identifying and addressing performance bottlenecks through asynchronous programming

• Identify bottlenecks using profiling tools like Chrome DevTools or Visual Studio Profiler

• Optimize code by using asynchronous programming techniques like callbacks, promises, or async/await

• Consider using web workers or service workers for offloading tasks to separate threads

• Use caching mechanisms to reduce redundant computations and improve response times

A COBOL program to print Fibonacci series using recursion.

• Use recursive function to calculate Fibonacci numbers

• Initialize variables for storing previous two Fibonacci numbers

• Print the Fibonacci series as it is calculated

Design a scalable and reliable messaging service component

• Use a distributed system architecture to handle high volume of messages

• Implement message queues for asynchronous communication

• Ensure message delivery with retries and acknowledgements

• Support message encryption for security

• Include monitoring and logging for performance tracking

To identify circles collided, check if the sum of their radii is greater than the distance between their centers.

• Calculate the distance between the centers of the two circles using the distance formula

• Add the radii of the two circles

• If the sum of the radii is greater than or equal to the distance between the centers, the circles have collided

CSS pre-processors are tools that extend the functionality of CSS by adding features like variables, nesting, and mixins.

• CSS pre-processors like Sass, Less, and Stylus allow for more efficient and organized CSS coding

• They offer features like variables, nesting, and mixins that make CSS code more modular and reusable

• Pre-processors need to be compiled into regular CSS before being used in a website

• They can be integrated into build tools like Grunt or Gulp for automated compilat...read more

PPH stands for Pages Per Hour. It is a productivity metric used in document processing.

• PPH measures the number of pages processed in an hour.

• It is commonly used in industries like printing, publishing, and data entry.

• PPH can be used to track individual or team productivity.

• Higher PPH indicates better efficiency and faster turnaround time.

• PPH is not a standardized metric and can vary depending on the type of document and processing method.

Inventory is a list of goods or materials held in stock by a business. Planning is the process of creating a strategy to achieve a goal.

• Inventory refers to the stock of goods or materials that a business holds.

• Planning involves creating a roadmap or strategy to achieve a specific goal or objective.

• Inventory management involves tracking and controlling the flow of goods or materials in and out of a business.

• Planning can involve setting goals, identifying resources, and creatin...read more

Implement LRU cache, Explain 5G PFCP headers, standard C++ questions.

• LRU cache can be implemented using a combination of a doubly linked list and a hashmap.

• 5G PFCP headers are used for communication between the control and user planes in 5G networks.

• Standard C++ questions may include topics like polymorphism, templates, and memory management.

Implement a telephone directory program using an array of strings.

• Create an array of strings to store the directory

• Implement functions to add, delete, and search for entries

• Consider using a hash table for faster search times

• Include error handling for invalid input

Design a High Level Diagram (HLD) for displaying the history of a web page.

• Use a database to store historical data of the web page

• Implement a version control system to track changes

• Display historical versions with timestamps on the web page

• Allow users to revert to previous versions if needed

Linux distributions can be found on official websites, community forums, and software repositories.

• Official websites of Linux distributions such as Ubuntu, Fedora, and Debian

• Community forums like Reddit's r/linux or LinuxQuestions.org

• Software repositories like apt-get for Debian-based distributions or yum for Red Hat-based distributions

The interface between RF and MAC messages involves the communication protocol and data exchange between the radio frequency and media access control layers.

• The RF layer is responsible for transmitting and receiving radio signals, while the MAC layer manages access to the communication medium.

• The interface between RF and MAC messages includes protocols like IEEE 802.11 for wireless LANs.

• RF messages typically contain physical layer information, while MAC messages contain data l...read more

Printing a tree in level order

• Use a queue to store nodes in level order

• Enqueue root node and print its value

• Dequeue the node and enqueue its children

• Repeat until queue is empty

Arrays have fixed size while slices are dynamic and can grow or shrink.

• Arrays have a fixed size determined at compile time, while slices are dynamic and can change in size during runtime.

• Arrays are passed by value, while slices are passed by reference.

• Arrays use square brackets [] for declaration, while slices use square brackets with a colon [:] to specify a range.

• Example: var arr [3]int = [1, 2, 3] // Array, var slice []int = []int{1, 2, 3} // Slice

Kaizen is a Japanese term for continuous improvement. OEE stands for Overall Equipment Effectiveness.

• Kaizen involves making small, incremental improvements to processes and systems over time.

• OEE is a metric used to measure the efficiency of manufacturing equipment.

• OEE takes into account factors such as availability, performance, and quality to determine overall effectiveness.

• Both kaizen and OEE are commonly used in lean manufacturing and Six Sigma methodologies.