Qmex Steel Construction Software Developer Interview Questions and Answers

Round duration - 45 minutes
Round difficulty - Easy

Technical interview round with questions on DSA, OS and DBMS.

Q1. 
Quick Sort Problem Statement
You are provided with an array of integers. The task is to sort the array in ascending order using the quick sort algorithm.
Quick sort is a divide-and-conquer algorithm. It ...read more
Ans. 
Yes, the quick sort algorithm can be enhanced to achieve NlogN complexity in the worst case by using a randomized pivot selection strategy.
• Use a randomized pivot selection strategy to reduce the chances of worst-case scenarios.

• Implement a hybrid sorting algorithm that switches to a different sorting algorithm like merge sort for small subarrays to improve performance.

• Optimize the partitioning process to reduce the numb...read more
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Q2. What is paging in operating systems?
Ans. 
Paging is a memory management scheme used by operating systems to store and retrieve data from secondary storage.
• Paging divides physical memory into fixed-size blocks called pages

• Virtual memory is divided into fixed-size blocks called frames

• Pages are mapped to frames in physical memory using a page table

• Allows for efficient memory management and enables larger virtual memory space than physical memory

• Example: When a pr...read more
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Q3. Design a banking management system and a railway management system.
Ans. 
Design a banking and railway management system.
• Banking management system should include features like account creation, transaction history, balance checking, etc.

• Railway management system should include features like ticket booking, seat availability, train schedules, etc.
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Q4. What is virtual memory?
Ans. 
Virtual memory is a memory management technique that allows a computer to compensate for physical memory shortages by temporarily transferring data from RAM to disk storage.
• Virtual memory allows a computer to run more programs than it has physical memory for.

• It creates an illusion of a larger memory space by using disk space as an extension of RAM.

• Pages of memory are swapped between RAM and disk storage based on usage.

• ...read more
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Q5. What is segmentation in operating systems?
Ans. 
Segmentation in operating systems is a memory management technique where memory is divided into segments of variable sizes.
• Segments are logical units of a program, such as code, data, stack, etc.

• Each segment has its own base address and length.

• Segmentation allows for protection and sharing of memory among processes.

• Examples include Intel x86 architecture with segment registers like CS, DS, SS, ES.
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Round duration - 45 minutes
Round difficulty - Easy

Technical Interview round with questions on Networking, Software Engineering etc.

Q1. Can you explain the leaky bucket algorithm?
Ans. 
Leaky bucket algorithm is a method for controlling traffic rates in network communication.
• The leaky bucket algorithm is a traffic shaping algorithm used in network communication to control the rate at which data is transmitted.

• It works by storing incoming data in a 'bucket' with a fixed capacity. If the bucket overflows, excess data is discarded.

• The bucket has a leak rate, which means that it can only hold a certain am...read more
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Q2. What is the difference between a switch and a hub in computer networking?
Ans. 
Switches operate at the data link layer and forward data based on MAC addresses, while hubs operate at the physical layer and broadcast data to all connected devices.
• Switches operate at the data link layer and make forwarding decisions based on MAC addresses.

• Switches create separate collision domains for each port, improving network performance.

• Hubs operate at the physical layer and simply broadcast data to all connect...read more
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Q3. What is the difference between TCP and UDP?
Ans. 
TCP is a connection-oriented protocol that guarantees delivery of data packets in order, while UDP is a connectionless protocol that does not guarantee delivery or order of packets.
• TCP is reliable and ensures data integrity, while UDP is faster but less reliable.

• TCP requires a connection to be established between sender and receiver before data transfer, while UDP does not require a connection.

• TCP uses flow control and...read more
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Q4. How many bits make up IPv4 and IPv6 addresses?
Ans. 
IPv4 addresses are 32 bits long, while IPv6 addresses are 128 bits long.
• IPv4 addresses consist of 32 bits, divided into four octets separated by periods (e.g. 192.168.1.1).

• IPv6 addresses consist of 128 bits, represented in hexadecimal format with colons separating each group of 4 hexadecimal digits (e.g. 2001:0db8:85a3:0000:0000:8a2e:0370:7334).
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Q5. What are the steps involved in a software engineering process?
Ans. 
Software engineering process involves multiple steps to develop high-quality software.
• Requirement analysis: Gather and analyze requirements from stakeholders.

• Design: Create a detailed design of the software based on requirements.

• Implementation: Write code based on the design.

• Testing: Test the software to ensure it meets requirements and is bug-free.

• Deployment: Deploy the software for users to use.

• Maintenance: Regularly...read more
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Q6. What are the principles of testing?
Ans. 
Principles of testing are guidelines that help in designing effective test cases and ensuring quality software.
• Testing shows presence of defects, not their absence

• Exhaustive testing is impossible, so prioritize and focus on high-risk areas

• Early testing saves time and cost in the long run

• Defect clustering - a small number of modules usually contain most of the defects

• Pesticide paradox - if the same tests are repeated, e...read more
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Round duration - 30 minutes
Round difficulty - Easy

HR round with typical behavioral problems.

Round duration - 45 minutes
Round difficulty - Medium

Technical Interview round entirely based on Networking

Q1. What is padding in computer networks?
Ans. 
Padding in computer networks refers to adding extra bits to data to ensure it meets a minimum length requirement.
• Padding is used to ensure that data packets are of a consistent size for transmission.

• It is commonly used in protocols like Ethernet and IP to fill up the remaining space in a packet.

• Padding can also be used for security purposes, such as in cryptographic algorithms where fixed-length blocks are required.

• For...read more
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Q2. What is the difference between HTTP and HTTPS?
Ans. 
HTTP is unsecured protocol while HTTPS is secured protocol using SSL/TLS encryption.
• HTTP stands for Hypertext Transfer Protocol, while HTTPS stands for Hypertext Transfer Protocol Secure.

• HTTP operates on port 80, while HTTPS operates on port 443.

• HTTPS uses SSL/TLS encryption to secure the communication between the client and server, while HTTP does not.

• HTTPS provides data integrity, authentication, and encryption, maki...read more
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Q3. What is the difference between TCP and UDP?
Ans. 
TCP is a connection-oriented protocol that ensures reliable data delivery, while UDP is a connectionless protocol that focuses on speed and efficiency.
• TCP is reliable as it guarantees delivery of data packets in the correct order, while UDP does not guarantee delivery or order of packets.

• TCP uses handshaking to establish a connection before data transfer, while UDP does not require a connection setup.

• TCP is slower but ...read more
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Round duration - 60 minutes
Round difficulty - Easy

Technical Interview round with questions on C Programming , OOPS concepts and Operating Systems mainly.

Q1. What does a static variable mean?
Ans. 
A static variable is a variable that retains its value between function calls.
• Static variables are declared using the 'static' keyword.

• They are initialized only once and retain their value throughout the program execution.

• They have a local scope within the function they are declared in.

• Static variables are commonly used for maintaining state across function calls.
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Q2. What are the uses of a pointer?
Ans. 
Pointers are used to store memory addresses of variables, dynamically allocate memory, create data structures like linked lists, and pass parameters by reference.
• Dynamically allocate memory

• Create data structures like linked lists

• Pass parameters by reference
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Q3. What are the differences between structures and arrays?
Ans. 
Arrays are a collection of similar data types stored in contiguous memory locations, while structures are a collection of different data types stored in non-contiguous memory locations.
• Arrays store elements of the same data type, while structures can store elements of different data types.

• Arrays are accessed using indices, while structures are accessed using member variables.

• Arrays have a fixed size, while structures c...read more
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Q4. What is a near pointer?
Ans. 
A near pointer is a pointer that stores the offset or relative address of a memory location within a limited range.
• Near pointers are commonly used in segmented memory models where the memory is divided into segments and each segment has a fixed size.

• They are limited in range and can only access memory within the same segment.

• Example: In x86 real mode, near pointers are used to access memory within a 64KB segment.
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Q5. What does the fork command do in operating systems?
Ans. 
The fork command creates a new process by duplicating the existing process.
• Fork command is used in operating systems to create a new process that is a copy of the existing process.

• The new process created by fork has its own memory space but shares the same code, data, and file descriptors with the parent process.

• Fork system call returns different values in the parent and child processes to distinguish between them.

• Exam...read more
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Q6. What are semaphores?
Ans. 
Semaphores are synchronization primitives used to control access to shared resources in a multi-threaded environment.
• Semaphores can be used to limit the number of threads accessing a resource simultaneously.

• They can be binary (mutex) or counting semaphores.

• Example: In a producer-consumer problem, semaphores can be used to control access to a shared buffer.
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Round duration - 60 minutes
Round difficulty - Easy

Technical Interview round with questions on C Programming , OOPS concepts and Networking mainly.

Q1. What is DNS?
Ans. 
DNS stands for Domain Name System, which translates domain names to IP addresses.
• DNS is like a phone book for the internet, translating human-readable domain names (like google.com) to IP addresses (like 172.217.3.206).

• It helps users access websites by typing in easy-to-remember domain names instead of complex IP addresses.

• DNS servers store records of domain names and their corresponding IP addresses, allowing for effi...read more
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Q2. What are routing protocols?
Ans. 
Routing protocols are a set of rules used by routers to determine the best path for data packets to travel in a network.
• Routing protocols help routers communicate with each other to dynamically update routing tables.

• They can be classified as either distance-vector or link-state protocols.

• Examples of routing protocols include RIP, OSPF, EIGRP, and BGP.
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Q3. Are the expressions *ptr++ and ++*ptr the same?
Ans. 
No, *ptr++ and ++*ptr are not the same. *ptr++ increments the pointer after accessing the value, while ++*ptr increments the value pointed to by the pointer.
• ptr = &arr[0]; *ptr++ accesses the value at arr[0] and then increments the pointer

• ptr = &arr[0]; ++*ptr increments the value at arr[0]
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Q4. What is invalid pointer arithmetic?
Ans. 
Invalid pointer arithmetic refers to performing arithmetic operations on a pointer that result in accessing memory outside the bounds of the allocated memory.
• Attempting to access memory beyond the bounds of an array using pointer arithmetic.

• Performing arithmetic operations on a pointer that points to a single variable.

• Using pointer arithmetic to access memory that has already been deallocated.
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Q5. What is the difference between an array of pointers and a pointer to an array?
Ans. 
Array of pointers stores memory addresses of individual elements, while pointer to an array stores the memory address of the entire array.
• Array of pointers: char *arr[3] = {"hello", "world", "example"};

• Pointer to an array: char (*ptr)[3] = arr;
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Q6. What is the difference between an array name and a pointer variable?
Ans. 
Array name is a constant pointer to the first element, while a pointer variable can be reassigned to point to different memory locations.
• Array name is a constant pointer to the first element

• Pointer variable can be reassigned to point to different memory locations

• Example: int arr[5]; int *ptr = arr; arr[0] = 10; ptr++; *ptr = 20;
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Round duration - 30 minutes
Round difficulty - Easy

Typical managerial round.

Round duration - 40 minutes
Round difficulty - Easy

The interview process last for around 30-40 minutes and it was elimination round. This round decide your placement. First of all interviewer ask about the language comfortable with, then lots of questions regarding C/C++ basics. After that he asks lot of questions about Pointers, Operating system, Data structure and Algorithms, GNU/Linux, SQL, Computer networks and everything mentioned on resume and good knowledge on Recursion(only few knows behind the scene of memory stack of recursion concept). Ask about GNU/LINUX and what I had done with OS with practical work. When he ask about DBMS i told him that I don't know theory and I am comfortable with SQL.

Q1. What is the difference between C and C++?
Ans. 
C is a procedural programming language while C++ is an object-oriented programming language with features like classes and inheritance.
• C is a procedural programming language while C++ is a multi-paradigm language with support for object-oriented programming.

• C does not support classes and objects, while C++ does.

• C does not have features like inheritance and polymorphism, which are supported in C++.

• C is a subset of C++, ...read more
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Q2. What is the difference between an Array and a Linked List?
Ans. 
Array is a fixed-size data structure while Linked List is a dynamic data structure with nodes connected by pointers.
• Array stores elements in contiguous memory locations, while Linked List stores elements in nodes with pointers to the next node.

• Array has constant time access to elements using index, while Linked List requires traversal from the head to access elements.

• Insertions and deletions are faster in Linked List a...read more
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Q3. What is the TCP/IP model?
Ans. 
The TCP/IP model is a networking protocol suite that defines how data is transmitted over the internet.
• Consists of four layers: Application, Transport, Internet, Link

• Each layer has specific protocols and functions

• Example: HTTP, FTP, TCP, IP, Ethernet

• Follows a bottom-up approach for data transmission
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Q4. What is a program counter?
Ans. 
The program counter is a register in a computer processor that indicates the address of the next instruction to be executed.
• It is a special-purpose register in a CPU that stores the memory address of the instruction being executed.

• The program counter is automatically incremented after fetching an instruction, pointing to the next instruction in memory.

• It plays a crucial role in the fetch-decode-execute cycle of the CPU...read more
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Q5. 
Reverse a String Problem Statement
Given a string STR containing characters from [a-z], [A-Z], [0-9], and special characters, determine the reverse of the string.
Input:
The input starts with a single i...read more
Ans. 
Reverse a given string containing characters from [a-z], [A-Z], [0-9], and special characters.
• Iterate through the characters of the string from end to start and append each character to a new string to get the reversed string.

• Use built-in functions like reverse() in some programming languages to reverse the string directly.

• Ensure to handle special characters and numbers while reversing the string.

• Return the reversed st...read more
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Q6. What is the SQL command to join two tables?
Ans. 
SQL command to join two tables is 'JOIN'.
• Use 'JOIN' keyword to combine rows from two or more tables based on a related column between them.

• Types of joins include INNER JOIN, LEFT JOIN, RIGHT JOIN, and FULL JOIN.

• Example: SELECT * FROM table1 JOIN table2 ON table1.column = table2.column;
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Round duration - 30 minutes
Round difficulty - Easy

HR round was just formality very less candidates are eliminated. HR was very nice guy. He ask me about projects I had done and other questions are related to job location, relocation and bond. Always say truth. When I was asked about why you are not placed yet i honestly told that most of the times i was rejected.