Cisco Software Developer Interview Questions, Process, and Tips

Round duration - 60 Minutes
Round difficulty - Medium

This was an Online Coding+MCQ round where we had a total of 25 MCQ questions and 1 coding problem. The coding problem was of easy to medium level and anyone with a decent knowledge of DSA could pass the coding problem.

Q1. 
Rat In a Maze Problem Statement
Given a N * N maze with a rat placed at position MAZE[0][0], find and print all possible paths for the rat to reach its destination at MAZE[N-1][N-1]. The rat is allowed to...read more
Ans. 
Find all possible paths for a rat in a maze to reach its destination.
• Use backtracking to explore all possible paths in the maze.

• Mark visited cells and backtrack when reaching dead ends.

• Print the path when reaching the destination cell.

• Consider all possible movements: left, right, up, and down.

• Ensure the rat can only move through cells marked as 1.
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Round duration - 60 Minutes
Round difficulty - Medium

The interviewer asked 1 coding problem related to Dynamic Programming in this round and then the rest of the questions were preety much revolving around Computer Networks.

Q1. 
Ways To Make Coin Change
Given an infinite supply of coins of varying denominations, determine the total number of ways to make change for a specified value using these coins. If it's not possible to make...read more
Ans. 
The task is to find the total number of ways to make change for a specified value using given denominations.
• Use dynamic programming to solve this problem efficiently.

• Create a 1D array to store the number of ways to make change for each value from 0 to the target value.

• Iterate through the denominations and update the array based on the current denomination.

• The final answer will be the value at the target index of the ar
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Q2. What is the difference between IPv4 and IPv6?
Ans. 
IPv6 has a larger address space, improved security features, and better support for mobile devices compared to IPv4.
• IPv4 uses 32-bit addresses while IPv6 uses 128-bit addresses.

• IPv4 supports around 4.3 billion unique addresses, whereas IPv6 supports 340 undecillion unique addresses.

• IPv6 has built-in security features like IPsec, while IPv4 requires additional security protocols.

• IPv6 has better support for mobile device...read more
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Q3. Can you describe the OSI Reference Model?
Ans. 
The OSI Reference Model is a conceptual framework that standardizes the functions of a telecommunication or computing system into seven layers.
• The OSI Reference Model stands for Open Systems Interconnection Reference Model.

• It consists of seven layers: Physical, Data Link, Network, Transport, Session, Presentation, and Application.

• Each layer has specific functions and communicates with the adjacent layers.

• The model help...read more
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Round duration - 60 minutes
Round difficulty - Medium

This round had 1 question related to Binary Tree Traversal followed by some core concepts related to Operating Systems. This round ended with the interviewer asking me the famous 2 wire burning puzzle.

Q1. 
Spiral Order Traversal of a Binary Tree
Given a binary tree with N nodes, your task is to output the Spiral Order traversal of the binary tree.
Input:
The input consists of a single line containing elem...read more
Ans. 
Implement a function to return the spiral order traversal of a binary tree.
• Traverse the binary tree in a spiral order, alternating between left to right and right to left at each level

• Use a queue to keep track of nodes at each level and a flag to switch direction

• Return the list of nodes in spiral order traversal
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Q2. What is memory protection in operating systems?
Ans. 
Memory protection in operating systems is a mechanism to prevent a process from accessing memory that has not been allocated to it.
• Memory protection prevents a process from accessing memory locations outside its allocated space.

• It helps in preventing one process from interfering with the memory of another process.

• Operating systems use techniques like virtual memory and access control lists to implement memory protectio...read more
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Q3. You have two wires of different lengths that take different times to burn. How can you measure a specific amount of time using these two wires?
Ans. 
Use two wires of different lengths to measure a specific amount of time by burning them simultaneously.
• Burn both wires at the same time, one wire will finish burning before the other

• Measure the time it takes for the first wire to burn completely

• Use this time as a reference to measure the specific amount of time by burning the second wire
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Round duration - 60 Minutes
Round difficulty - Medium

This was an Online Coding+MCQ round where we had a total of 50 MCQ questions and 1 coding problem. The coding problem was of easy to medium level.

Q1. 
Add Two Numbers Represented as Linked Lists
Given two linked lists representing two non-negative integers, where the digits are stored in reverse order (i.e., starting from the least significant digit to ...read more
Ans. 
Add two numbers represented as linked lists in reverse order and return the sum as a linked list.
• Traverse both linked lists simultaneously while keeping track of carry.

• Create a new linked list to store the sum digits.

• Handle cases where one list is longer than the other or there is a final carry.

• Remember to reverse the final linked list before returning the head.
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Round duration - 60 Minutes
Round difficulty - Medium

This round had 1 question related to Binary Tree Traversal and then the rest of the questions that the interviewer asked me were mostly related to OOPS and C++.

Q1. 
Level Order Traversal Problem Statement
Given a binary tree of integers, return the level order traversal of the binary tree.
Input:
The first line contains an integer 'T', representing the number of te...read more
Ans. 
Return the level order traversal of a binary tree given in level order with null nodes represented by -1.
• Create a queue to store nodes for level order traversal

• Start with the root node, enqueue it, then dequeue and print its value, enqueue its children, repeat until queue is empty

• Handle null nodes represented by -1 by skipping them during traversal
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Q2. What is a namespace in C++?
Ans. 
A namespace in C++ is a declarative region that provides a scope for the identifiers within it.
• Namespaces help in organizing code by grouping related classes, functions, and variables.

• They prevent naming conflicts by allowing the same name to be used in different namespaces.

• Example: namespace myNamespace { int x; }

• Example: using namespace std; // for using standard library functions without prefix
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Q3. Why do we need the Friend class and function in Object-Oriented Programming?
Ans. 
Friend class and function in OOP allows specific classes or functions to access private and protected members of a class.
• Friend class/function can access private and protected members of a class without violating encapsulation.

• It allows for selective sharing of data between classes without exposing all members to the outside world.

• Friendship is not mutual - a class can declare another class as a friend, but the other c...read more
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Q4. What does a static member in C++ mean?
Ans. 
A static member in C++ is a member of a class that is shared among all instances of the class.
• Static members are declared using the 'static' keyword.

• They are not associated with any specific instance of the class, but rather with the class itself.

• They can be accessed using the scope resolution operator '::'.

• Static members are commonly used for constants, utility functions, or shared data among all instances of a class.
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Round duration - 60 minutes
Round difficulty - Medium

This round was more aligned towards Computer Networks and had 1 question of DSA realted to Binary Trees and the interview ended with the famous Die-Hard Puzzle.

Q1. 
Spiral Order Traversal of a Binary Tree
Given a binary tree with N nodes, your task is to output the Spiral Order traversal of the binary tree.
Input:
The input consists of a single line containing elem...read more
Ans. 
Implement a function to return the spiral order traversal of a binary tree.
• Traverse the binary tree level by level, alternating the direction of traversal from left to right and right to left.

• Use a queue to keep track of nodes at each level and a stack to reverse the order of nodes at even levels.

• Handle null nodes appropriately to maintain the spiral order traversal.

• Example: For input 1 2 3 -1 -1 4 5, the output should
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Q2. Can you describe the OSI Reference Model?
Ans. 
The OSI Reference Model is a conceptual framework that standardizes the functions of a telecommunication or computing system into seven layers.
• The OSI Reference Model stands for Open Systems Interconnection Reference Model.

• It consists of seven layers: Physical, Data Link, Network, Transport, Session, Presentation, and Application.

• Each layer has specific functions and communicates with the adjacent layers.

• The model help...read more
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Q3. What is the use of a router and how does it differ from a gateway?
Ans. 
A router is a networking device that forwards data packets between computer networks. It differs from a gateway in terms of functionality and scope.
• A router operates at the network layer of the OSI model, making decisions based on IP addresses.

• Routers connect multiple networks together and determine the best path for data to travel.

• Gateways, on the other hand, translate between different types of networks or protocols.

• ...read more
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Q4. How can you measure exactly 4 liters of water using only a 3-liter can and a 5-liter can?
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Round duration - 60 Minutes
Round difficulty - Easy

It was in the morning. Because of covid test was from home. We had 50 MCQ and 1 coding question. The coding question was pretty easy. MCQ were mixed, we even had questions from machine learning.

Q1. 
Maximum Path Sum Between Two Leaves
Given a non-empty binary tree where each node has a non-negative integer value, determine the maximum possible sum of the path between any two leaves of the given tree.
...read more
Ans. 
Find the maximum path sum between two leaf nodes in a binary tree.
• Traverse the tree to find the maximum path sum between two leaf nodes

• Consider both cases where the path passes through the root and where it doesn't

• Keep track of the maximum sum while traversing the tree
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Round duration - 60 minutes
Round difficulty - Medium

Interview round. Questions were based on projects, database and one coding question

Q1. 
Longest Subarray Zero Sum Problem Statement
Given an array of integers arr, determine the length of the longest contiguous subarray that sums to zero.
Input:
N (an integer, the length of the array)
arr (...read more
Ans. 
Find the length of the longest contiguous subarray that sums to zero in an array of integers.
• Use a hashmap to store the cumulative sum and its corresponding index.

• Iterate through the array, updating the sum and checking if the current sum exists in the hashmap.

• If the sum exists in the hashmap, update the maximum length of subarray with sum zero.

• Return the maximum length of subarray with sum zero.
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Round duration - 40 minutes
Round difficulty - Easy

Managerial round. Was asked questions on projects and management

Round duration - 10 minutes
Round difficulty - Easy

HR just asked about basic stuffs and all. Nothing technical

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.