Juniper Networks Software Designer Interview Questions and Answers

2 coding questions and a set of mcq questions based on oops, dbms, networking and os

Q1. Reverse a linked list
Ans. 
Reverse a linked list
• Iteratively swap the next and previous pointers of each node

• Use three pointers to keep track of the current, previous, and next nodes

• Update the head pointer to the last node after reversing
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Q2. What is the point of BST?
Ans. 
BST is a data structure used for efficient searching, insertion and deletion of elements in a sorted manner.
• BST stands for Binary Search Tree.

• It has a root node and every node has at most two children.

• The left subtree of a node contains only nodes with keys lesser than the node's key.

• The right subtree of a node contains only nodes with keys greater than the node's key.

• BST allows for efficient searching, insertion and d...read more
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Round duration - 60 Minutes
Round difficulty - Easy

This was the initial round consisting of some aptitude questions,technical multiple choice questions and one coding question.
The Multiple Choice Questions were pretty straight forward.

Q1. 
Snake and Ladder Problem Statement
Given a 'Snake and Ladder' board with N rows and N columns, where positions are numbered from 1 to (N*N) starting from the bottom left, alternating direction each row, f...read more
Ans. 
Find the minimum number of dice throws required to reach the last cell on a 'Snake and Ladder' board.
• Start from the bottom left cell and move according to dice outcomes (1-6).

• Utilize snakes and ladders to reach the last cell faster.

• Keep track of the minimum number of throws required to reach the last cell.

• If unreachable, return -1 as output.
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Round duration - 45 Minutes
Round difficulty - Medium

I had two interviewers in this round.Some Problem solving questions were asked in this round.

Q1. 
Anagram Pairs Verification Problem
Your task is to determine if two given strings are anagrams of each other. Two strings are considered anagrams if you can rearrange the letters of one string to form the...read more
Ans. 
Check if two strings are anagrams of each other by comparing their sorted characters.
• Sort the characters of both strings and compare them.

• Use a dictionary to count the frequency of characters in each string and compare the dictionaries.

• Ensure both strings have the same length before proceeding with comparison.

• Example: For input 'spar' and 'rasp', after sorting both strings, they become 'aprs' which are equal, so return
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Q2. Can you explain all the main Object Oriented Programming concepts?
Ans. 
Object Oriented Programming concepts include encapsulation, inheritance, polymorphism, and abstraction.
• Encapsulation: Bundling data and methods that operate on the data into a single unit (class). Example: Class Car with properties like color and methods like drive().

• Inheritance: Creating new classes based on existing classes, inheriting their attributes and methods. Example: Class SUV inheriting from class Car.

• Polymor...read more
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Q3. Can you explain one of your projects?
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Round duration - 45 Minutes
Round difficulty - Easy

Number Of Interviewers : 2
I was asked two problem solving questions and I was asked to explain my projects.

Round duration - 60 minutes
Round difficulty - Medium

The test was in the evening which was not too late. It was conducted on Hackerrank which is a very common platform and was hence familiar. There were 26 questions:
Q1: Coding Question
3 languages were allowed: c, java8, python3
Q2 - Q26: Multiple Choice Questions

Q1. 
Intersection of Linked List Problem
You are provided with two singly linked lists containing integers, where both lists converge at some node belonging to a third linked list.
Your task is to determine t...read more
Ans. 
Find the node where two linked lists merge, return -1 if no merging occurs.
• Traverse both lists to find the lengths and the last nodes

• Align the starting points of both lists by moving the longer list's pointer ahead by the difference in lengths

• Traverse both lists simultaneously until a common node is found, which is the merging point
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Round duration - 60 minutes
Round difficulty - Easy

Technical Interview round with questions on OOPS and OS mainly.

Q1. What are Little Endian and Big Endian in the context of computer architecture?
Ans. 
Little Endian and Big Endian refer to the order in which bytes are stored in computer memory.
• Little Endian stores the least significant byte first, while Big Endian stores the most significant byte first.

• Little Endian is commonly used in x86 architecture, while Big Endian is used in architectures like SPARC and PowerPC.

• Endianness can affect data transmission between systems with different byte orders.
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Q2. Write a program to determine if your system is little-endian or big-endian.
Ans. 
Program to determine system's endianness
• Check the endianness by storing a multi-byte integer and checking the byte order

• Use bitwise operations to extract the least significant byte

• If the least significant byte is at the lowest memory address, it's little-endian

• If the least significant byte is at the highest memory address, it's big-endian
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Q3. What is the volatile keyword in programming?
Ans. 
The volatile keyword in programming is used to indicate that a variable's value can be changed unexpectedly.
• Volatile keyword is used in multithreaded programming to prevent compiler optimizations on variables that can be changed by other threads.

• It tells the compiler not to cache the variable's value in a register, ensuring that every access is made to the variable's memory location.

• Commonly used in embedded systems pr...read more
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Q4. What is the use of a function pointer in C?
Ans. 
Function pointers in C are used to store the address of functions, allowing for dynamic function calls and callbacks.
• Function pointers can be used to implement callbacks in event-driven programming.

• They can be used to switch between different functions at runtime.

• Function pointers are commonly used in implementing data structures like function pointers in an array of function pointers.

• Example: void (*funcPtr)(int) = &a
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Q5. Design a data structure to implement multi-threading.
Ans. 
Design a data structure for multi-threading
• Use a thread-safe queue to manage tasks for each thread

• Implement a lock or semaphore to control access to shared resources

• Consider using condition variables for synchronization

• Use atomic operations for shared variables to prevent race conditions
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Q6. What does a kernel do?
Ans. 
The kernel is the core component of an operating system that manages system resources and provides a bridge between software and hardware.
• Manages system resources such as CPU, memory, and I/O devices

• Provides a bridge between software applications and hardware components

• Handles tasks such as process scheduling, memory management, and device drivers

• Controls communication between hardware and software layers
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Q7. What is a storage class in programming?
Ans. 
A storage class in programming defines the scope and lifetime of variables.
• Storage classes include auto, register, static, and extern.

• Auto variables are created when a function is called and destroyed when the function ends.

• Register variables are stored in CPU registers for faster access.

• Static variables retain their value between function calls.

• Extern variables are declared outside of any function and can be accessed
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Round duration - 30 minutes
Round difficulty - Easy

HR round with typical behavioral problems.