40+ Amazon Interview Questions and Answers

A /24 address can have 256 clients. Network address is the first IP and broadcast address is the last IP.

• A /24 address has 256 IP addresses

• The network address is the first IP in the range

• The broadcast address is the last IP in the range

A router is needed to connect two computers in different networks or to share internet connection.

• When two computers are in different networks, a router is needed to connect them.

• A router can also be used to share internet connection between multiple devices.

• Routers can provide additional security features like firewall and VPN.

• Examples of routers include Cisco, Netgear, and TP-Link.

ArrayList is a resizable array while LinkedList is a doubly linked list.

• ArrayList is faster for accessing elements while LinkedList is faster for adding or removing elements.

• ArrayList uses contiguous memory while LinkedList uses non-contiguous memory.

• ArrayList is better for random access while LinkedList is better for sequential access.

• Example: ArrayList - List names = new ArrayList<>(); LinkedList - List names = new LinkedList<>();

Possible security issues and how to manage them in web applications

• SQL injection attacks

• Cross-site scripting (XSS) attacks

• Cross-site request forgery (CSRF) attacks

• Insecure authentication and authorization mechanisms

• Sensitive data exposure

• Implementing secure coding practices

• Regularly updating software and security patches

• Conducting regular security audits and penetration testing

• Implementing multi-factor authentication

• Using HTTPS and SSL/TLS encryption

• Limiting access to sensiti...read more

Object-oriented languages support inheritance and polymorphism, while object-based languages do not.

• Object-oriented languages allow for the creation of classes and objects, and support inheritance and polymorphism.

• Object-based languages only support objects, but do not have the concept of classes or inheritance.

• Examples of object-oriented languages include Java, C++, and Python, while JavaScript is an example of an object-based language.

Entering a URL in the browser triggers a series of events to retrieve and display the requested webpage.

• The browser checks the cache for a previously stored copy of the webpage

• If not found, the browser sends a request to the DNS server to resolve the domain name to an IP address

• The browser then sends a request to the web server at the IP address for the webpage

• The web server responds with the requested webpage

• The browser renders the webpage and displays it to the user

Virtual memory is a memory management technique that allows a computer to use more memory than physically available.

• Virtual memory is created by using hard disk space as an extension of RAM.

• It allows running more programs than the physical memory can handle.

• The size of virtual memory is typically larger than the size of main memory.

• Virtual memory is divided into pages, which are swapped in and out of main memory as needed.

• Examples of virtual memory include Windows pagefile an...read more

Anycast, unicast, and multicast are different ways of routing network traffic.

• Unicast is one-to-one communication between a sender and a receiver.

• Anycast is one-to-nearest communication where the sender sends a message to the nearest receiver.

• Multicast is one-to-many communication where the sender sends a message to a group of receivers.

• Anycast is used for load balancing and finding the nearest server.

• Unicast is used for regular client-server communication.

• Multicast is used f...read more

Async in JS allows non-blocking code execution despite being single-threaded.

• JS uses event loop to handle async operations

• Callbacks, Promises, and Async/Await are used for async programming

• setTimeout() and setInterval() are examples of async functions

• JS runtime delegates async tasks to the browser or Node.js environment

• Async code can improve performance and user experience

MAC addresses are required for identifying devices on a local network, while IP addresses are used for identifying devices on a global network.

• MAC addresses are used for communication within a local network

• IP addresses are used for communication across different networks

• MAC addresses are assigned by the manufacturer and cannot be changed

• IP addresses can be assigned dynamically or statically

• MAC addresses are used in the data link layer of the OSI model

• IP addresses are used in ...read more

Program to print binary tree elements in spiral order

• Use two stacks to keep track of nodes at odd and even levels

• Push nodes from left to right in odd level stack and right to left in even level stack

• Pop nodes from the stack alternatively and print them

• Repeat until both stacks are empty

IPv4 has 32 bits and IPv6 has 128 bits.

• IPv4 addresses are in the format of xxx.xxx.xxx.xxx where each xxx is an 8-bit number.

• IPv6 addresses are in the format of xxxx:xxxx:xxxx:xxxx:xxxx:xxxx:xxxx:xxxx where each xxxx is a 16-bit number.

• IPv6 addresses allow for a much larger number of unique addresses than IPv4.

Inheritance is a way to create new classes based on existing ones. Abstraction is a way to hide implementation details.

• Inheritance allows a subclass to inherit properties and methods from a superclass.

• Abstraction allows a class to provide a simplified interface to its users while hiding its implementation details.

• For example, a Car class can inherit properties and methods from a Vehicle class, while also implementing its own unique features.

• Abstraction can be seen in a TV rem...read more

Event bubble and capture are two ways of propagating events in the DOM tree.

• Event bubble is the default behavior where an event is first captured by the innermost element and then propagated to the outer elements.

• Event capture is the opposite of event bubble where an event is first captured by the outermost element and then propagated to the inner elements.

• Both event bubble and capture can be used together to handle events in a more controlled way.

• Event.stopPropagation() meth...read more

TCP is a protocol that ensures reliable communication by establishing a connection, managing data transfer, and handling errors.

• TCP establishes a connection between two devices before data transfer begins.

• It breaks data into packets and numbers them for sequencing.

• It uses acknowledgments and retransmissions to ensure all packets are received.

• TCP handles flow control by adjusting the transmission rate based on receiver's capacity.

• It also handles congestion control by detecting...read more

Implement a queue using two stacks by using one stack for enqueue operation and another stack for dequeue operation.

• Use one stack for enqueue operation by pushing elements onto it.

• Use another stack for dequeue operation by popping elements from it. If the dequeue stack is empty, transfer all elements from the enqueue stack to the dequeue stack.

• Maintain the order of elements by transferring elements between the two stacks as needed.

IPv6 is needed due to the exhaustion of IPv4 addresses and the need for more unique IP addresses.

• IPv6 provides a significantly larger address space compared to IPv4.

• It allows for the allocation of unique IP addresses to every device connected to the internet.

• IPv6 supports improved security features and better network performance.

• It enables the growth of Internet of Things (IoT) devices and services.

• Transitioning to IPv6 ensures the long-term sustainability of the internet.

An ArrayList is a dynamic array in Java that can grow or shrink in size during runtime.

• ArrayList is a class in Java's Collection framework.

• It implements the List interface and allows duplicate elements.

• Elements can be added or removed using methods like add(), remove(), etc.

• It can also be sorted using the sort() method.

• Example: ArrayList names = new ArrayList<>();

• names.add("John"); names.add("Mary"); names.remove(0);

Generate a spiral order traversal of a given matrix in clockwise direction

• Initialize variables for top, bottom, left, right boundaries

• Iterate through the matrix in a spiral order while adjusting boundaries

• Add elements to the result array in the spiral order

I am not comfortable discussing my personal life in a professional interview.

• I prefer to keep my personal life separate from my professional life.

• I believe in maintaining a work-life balance.

• I am fully committed to my work and will prioritize it over personal matters.

• I appreciate the question, but I would rather not discuss my honeymoon plans.

OSI stack has 7 layers that define how data is transmitted over a network.

• OSI stands for Open Systems Interconnection

• Each layer has a specific function and communicates with adjacent layers

• Layers are: Physical, Data Link, Network, Transport, Session, Presentation, Application

Code to reverse linked list using recursion

• Create a recursive function to traverse the linked list

• Swap the next and previous nodes in each recursive call

• Return the new head of the reversed linked list

Using stack to find the next greater element in an array

• Create an empty stack to store indices of elements

• Iterate through the array from right to left

• Pop elements from stack until a greater element is found or stack is empty

A multi user job scheduler allows multiple users to schedule and manage their tasks efficiently.

• Implement a centralized job scheduling system that can handle multiple users and their tasks simultaneously

• Include features such as task prioritization, deadline management, and resource allocation

• Use a database to store user information, task details, and scheduling algorithms

• Provide a user-friendly interface for users to create, edit, and monitor their scheduled tasks

Find the maximum element in a singly linked list.

• Traverse the list and keep track of the maximum element seen so far.

• Compare each element with the current maximum and update if necessary.

• Return the maximum element at the end of the traversal.

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 deletion of elements in O(log n) time complexity.

• Example: S...read more

Performance improvements in Angular can be achieved through lazy loading, AOT compilation, and optimizing change detection.

• Lazy loading: load modules only when needed

• AOT compilation: pre-compile templates for faster rendering

• Optimizing change detection: use OnPush strategy, avoid unnecessary bindings

• Use trackBy function for ngFor loops

• Use pure pipes instead of impure pipes

• Use ngZone.runOutsideAngular() for heavy computations

• Use Web Workers for parallel processing

• Minimize HTTP...read more

The test went well, I was able to complete all the tasks within the given time frame.

• I prepared well for the test by reviewing relevant materials

• I managed my time effectively during the test

• I was able to solve all the problems and complete all the tasks

• I double-checked my work to ensure accuracy

Yes

• Knowledge of network protocols and architectures

• Understanding of data structures and algorithms

• Experience with network troubleshooting and analysis

• Familiarity with network security and encryption

• Proficiency in network programming and socket programming

A microservice is a small, independent, and loosely coupled service that performs a specific business function.

• Microservices are designed to be small and focused on a single task or business function.

• They communicate with each other through APIs.

• Each microservice can be developed, deployed, and scaled independently.

• Examples include user authentication service, payment processing service, and notification service.

HTTP headers are key-value pairs sent between the client and server to provide additional information about the request or response.

• HTTP headers consist of a key-value pair separated by a colon, with each pair separated by a new line

• Headers are used to provide information such as content type, content length, caching directives, authentication credentials, etc.

• Example: 'Content-Type: application/json'

call, apply, and bind are methods in JavaScript used to manipulate the context of a function.

• call - calls a function with a given 'this' value and arguments provided individually.

• apply - calls a function with a given 'this' value and arguments provided as an array.

• bind - creates a new function that, when called, has its 'this' keyword set to the provided value.

Sorting an array of strings and merging them into a single string

• Use a sorting algorithm like quicksort or mergesort to sort the array of strings

• After sorting, merge the sorted strings into a single string using a loop or built-in functions like join()

Meta classes are classes that define the behavior of other classes.

• Meta classes are used to customize the behavior of classes.

• They can be used to add or modify attributes and methods of classes.

• They can also be used to enforce certain rules or restrictions on classes.

• In Python, the default meta class is 'type'.

• Example: class MyMeta(type): pass

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

Currying is a technique in functional programming where a function with multiple arguments is transformed into a sequence of functions, each taking a single argument.

• Currying helps in creating reusable functions and improving code readability.

• It allows partial application of functions, where some arguments are fixed and others are left to be provided later.

• Example: const add = a => b => a + b; add(2)(3) will return 5.

Routers connect different networks, while switches connect devices within a network.

• Routers operate at the network layer and make decisions based on IP addresses

• Switches operate at the data link layer and use MAC addresses to forward data

• Routers can connect multiple networks together, while switches connect devices within the same network

• Example: A router connects a home network to the internet, while a switch connects devices within the home network

Rate limiter design to control the rate of requests to a system

• Implement a token bucket algorithm to limit the number of requests per unit of time

• Use a sliding window algorithm to track and limit the number of requests within a specific time frame

• Consider using a distributed rate limiter for scalability and reliability

Sorting an array of strings in alphabetical order

• Use a sorting algorithm like quicksort or mergesort

• Ensure the sorting is case-insensitive if needed

• Consider using built-in sorting functions in programming languages like sort() in Python