Paychex IT Solutions India IT System Engineer Interview Questions and Answers

Round duration - 60 minutes
Round difficulty - Easy

Technical interview round with questions based on DSA and OOPS.

Q1. How do you dynamically allocate a 2D array in C?
Ans. 
Use double pointer to dynamically allocate memory for array of strings in C.
• Declare a double pointer to hold the 2D array of strings.

• Allocate memory for the rows first using malloc.

• Then allocate memory for each string in the row using malloc.

• Assign values to the strings in the array.

• Example: char **array = malloc(rows * sizeof(char *));

• Example: array[i] = malloc(strlen(str) + 1); strcpy(array[i], str);
Answered by AI
Add your answer
Q2. What are virtual functions in C++?
Ans. 
Virtual functions in C++ are functions that can be overridden in derived classes, allowing for polymorphic behavior.
• Virtual functions are declared using the 'virtual' keyword in the base class.

• They are used to achieve runtime polymorphism in C++.

• Derived classes can override the virtual functions defined in the base class.

• Example: class Base { public: virtual void display() { cout << 'Base class dis...read more
Answered by AI
Add your answer
Q3. What are virtual base classes?
Ans. 
Virtual base classes are classes that are inherited virtually to avoid multiple instances of the same base class in a derived class hierarchy.
• Virtual base classes are used in multiple inheritance to prevent the Diamond Problem.

• They are declared with the 'virtual' keyword in the base class.

• When a class inherits a virtual base class, the most derived class is responsible for initializing the virtual base class.

• Example: c...read more
Answered by AI
Add your answer

Round duration - 60 minutes
Round difficulty - Easy

Technical interview round with questions based on OS/Networking etc.

Q1. What is the system call that creates a separate connection?
Ans. 
The system call that creates a separate connection is fork()
• fork() is a system call in Unix-like operating systems that creates a new process by duplicating the existing process

• The new process created by fork() is called the child process, while the original process is called the parent process

• fork() is commonly used in network programming to create separate connections for handling multiple clients
Answered by AI
Add your answer
Q2. What does the epoll_wait() system call do?
Ans. 
epoll_wait() system call waits for events on an epoll instance
• Used in Linux for I/O event notification

• Blocks until one or more file descriptors become ready

• Returns the number of file descriptors ready for I/O operations
Answered by AI
Add your answer
Q3. What are the different protocols used in the transport layer?
Ans. 
Different protocols used in the transport layer include TCP, UDP, SCTP, and DCCP.
• TCP (Transmission Control Protocol) - reliable, connection-oriented protocol used for most internet communication

• UDP (User Datagram Protocol) - connectionless protocol used for applications where speed is more important than reliability

• SCTP (Stream Control Transmission Protocol) - supports multiple streams of data, used for telecommunicati...read more
Answered by AI
Add your answer
Q4. 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.
• TCP is reliable and ensures data delivery by establishing a connection before sending data.

• UDP is faster but less reliable as it does not establish a connection before sending data.

• TCP is used for applications that require high reliability and error correction, such as web browsing and...read more
Answered by AI
Add your answer

Round duration - 60 minutes
Round difficulty - Easy

Technical interview round with questions based on Networking etc.

Q1. What is the purpose of ICMP?
Ans. 
ICMP is a protocol used for error reporting, diagnostics, and network management in IP networks.
• ICMP is used to report errors in packet delivery

• It is used for network diagnostics and troubleshooting

• ICMP messages are encapsulated within IP packets

• Examples include ping (echo request/reply) and traceroute
Answered by AI
Add your answer
Q2. What are the types of connection release supported by TCP?
Ans. 
TCP supports four types of connection release: active close, passive close, simultaneous close, and abortive close.
• Active close: Client initiates the connection release process by sending a FIN packet.

• Passive close: Server initiates the connection release process by sending a FIN packet.

• Simultaneous close: Both client and server send FIN packets to each other simultaneously.

• Abortive close: Connection is terminated abru...read more
Answered by AI
Add your answer
Q3. What protocols are used by the MAC layer?
Ans. 
The MAC layer uses protocols like CSMA/CA, CSMA/CD, and TDMA to manage access to the network.
• CSMA/CA (Carrier Sense Multiple Access with Collision Avoidance) is used in wireless networks to avoid collisions.

• CSMA/CD (Carrier Sense Multiple Access with Collision Detection) is used in wired networks to detect and handle collisions.

• TDMA (Time Division Multiple Access) is used in networks where devices are assigned specific
Answered by AI
Add your answer
Q4. What is the ARP protocol?
Ans. 
ARP (Address Resolution Protocol) is a protocol used to map an IP address to a MAC address in a local network.
• ARP is used to resolve IP addresses to MAC addresses in a local network.

• It operates at the data link layer of the OSI model.

• ARP requests are broadcasted to all devices on the network.

• Example: When a device wants to communicate with another device on the same network, it uses ARP to find the MAC address correspo
Answered by AI
Add your answer