FULL-STACK DEVELOPER INTERVIEW QUESTIONS AND ANSWERS

Programming Languages/Frameworks/Platforms

Android

AngularJS

12 Essential AngularJS Interview Questions from Toptal
An AngularJS exam with questions from beginner to expert by @gdi2290 from @AngularClass
29 AngularJS Interview Questions – Can You Answer Them All? Great Article from Codementor
AngularJS interview questions and answers for experienced developers
AngularJS Interview Questions which have been designed specially to get you acquainted with the nature of questions you may encounter during your interview for the subject of AngularJS
This article discusses the top 50 Most occurred AngularJS interview question with answers
Top 25 Angularjs Interview Questions and Quiz
100 AngularJS Interview Questions - Quick Refresher

Angular

BackboneJS

C++

C

C#

.NET

Clojure

CSS

Cucumber

Django

Docker

Elastic

Top Elastic Stack Interview Questions

EmberJS

Erlang

Top 22 Erlang Interview Questions for both freshers and experienced developers

Golang

GraphQl

HTML

Ionic

iOS

Java

JavaScript

jQuery

Front-end build tools

KnockoutJS

Less

Top 25 LESS Interview Questions

Lisp

NodeJS

Objective-C

PHP

Python

Ruby on Rails

ReactJS

Ruby

Rust

Sass

Scala

SharePoint

Shell

Top 50 Shell Scripting Interview Questions from Career Guru

Spark

Carefully Curated 70 Spark Questions with Additional Optimization Guides (First in the series)

Swift

Vue.js

List of 300 VueJS Interview Questions

WordPress

TypeScript

Database technologies

Cassandra

Top 23 Cassandra Interview Questions from Career Guru

Microsoft Access

Top 16 Microsoft Access Database Interview Questions from Career Guru

MongoDB

MySQL

Neo4j

Top 20 Neo4j Interview Questions from Career Guru

Oracle

General Oracle Interview Questions & Answers

Postgres

SQL

SQLite

Top 20 SQLITE Interview Questions from Career Guru

Caching technologies

Memcached

Redis

OS

Linux

Windows

DevOps

Algorithms

Blockchain

Coding exercises

Comprehensive lists

Design Patterns

Data structures

Networks

Security

Data Science

FULL-STACK DEVELOPER INTERVIEW QUESTIONS AND ANSWERS

[⬆]** **Architecture:

Design principles. (DRY, KISS, YAGNI, Occam's razor, Worse is better, convention over configuration, separation of concerns, Law of Demeter (principle of least knowledge), boy scout rule, single source of truth, single version of truth, principle of least astonishment, let it crash principle, inversion of control)
SOLID

Rule

Description

A module should be responsible to one, and only one, actor.

A software artifact should be open for extension but closed for modification.

It should be possible to substitute base class with derived class.

Many client-specific interfaces are better than one general-purpose interface.

Depend upon Abstractions but not on concretions. This means that each module should be separated from other using an abstract layer which binds them together. Source code dependency points in the opposite direction compared to the flow of control.

The Clean Architecture
Clean Code Cheat Sheet
One key abstraction
Aspect-oriented programming
The Twelve-Factor App
Domain-driven design
Microservices are a style of software architecture that involves delivering systems as a set of very small, granular, independent collaborating services.
- Pros of microservices (The services are easy to replace, Services can be implemented using different programming languages, databases, hardware and software environment, depending on what fits best)
Design patterns.
- Creational: Builder, Object Pool, Factory Method, Singleton, Multiton, Prototype, Abstract Factory
- Structural: Adapter, Bridge, Composite, Decorator, Facade, Flyweight, Proxy
- Behavioral: Chain of Responsibility, Command, Interpreter, Iterator, Mediator, Memento, Observer, State, Strategy, Template Method, Visitor
Enterprise integration patterns, SOA patterns.
3-tier architecture (Presentation tier, Application tier, Data tier)
3-layer architecture (DAO (Repository), Business (Service) layer, Controller)
REST (Representational state transfer), RPC
Idempotent operation (The PUT and DELETE methods are referred to as idempotent, meaning that the operation will produce the same result no matter how many times it is repeated)
Nullipotent operation (GET method is a safe method (or nullipotent), meaning that calling it produces no side-effects)
Naked objects, Restful objects.
Why do you need web server (tomcat, jetty)?
Inheritance vs Composition (Inheritance - is-a relationship, whether clients will want to use the subclass type as a superclass type. Composition - has-a or part-of relationship).
Multiple inheritance (diamond) problem
Advantages of using modules. (reuse, decoupling, namespace)
Drawbacks of not using separation of concerns
- Adding new features will take an order of magnitude longer
- Impossible to optimize
- Extremely difficult to test
- Fixing and debugging can be a nightmare (fixing something in one place can lead to something else breaking that seems completely unrelated).
What is uniform access principle? (client code should not be affected by a decision to implement an attribute as a field or method)
Conway's law (organizations which design systems ... are constrained to produce designs which are copies of the communication structures of these organizations)
GRASP

[⬆]** **Concurrency:

What is deadlock, livelock? (Deadlock is a situation in which two or more competing actions are each waiting for the other to finish, and thus neither ever does. A livelock is similar to a deadlock, except that the states of the processes involved in the livelock constantly change with regard to one another, none progressing.)
Deadlock avoidance. (prevention, detection, avoidance (Mutex hierarchy), and recovery)
What is starvation? (a problem encountered in concurrent computing where a process is perpetually denied necessary resources to process its work)
What is race condition? (Behavior of software system where the output is dependent on the sequence or timing of other uncontrollable events)
What is happens-before relation?
What is thread contention? (Contention is simply when two threads try to access either the same resource or related resources in such a way that at least one of the contending threads runs more slowly than it would if the other thread(s) were not running). Contention occurs when multiple threads try to acquire a lock at the same time
What is a thread-safe function? (Can be safely invoked by multiple threads at the same time)
Publish/Subscribe pattern
What is 2-phase locking? (Growing phase, shrinking phase. Guarantees serializablity for transactions, doesn't prevent deadlock).
What is the difference between thread and process? (Threads (of the same process) run in a shared memory space, while processes run in separate memory spaces)
What is false sharing, cache pollution, cache miss, thread affinity, ABA-problem, speculative execution?
What is a
- obstruction-free - if all other threads are paused, then any given thread will complete its operation in a bounded number of steps
- lock-free - if multiple threads are operating on a data structure, then after a bounded number of steps one of them will complete its operation
- wait-free - every thread operating on a data structure will complete its operation in a bounded number of steps, even if other threads are also operating on the data structure
algorithm?
What is sequential consistency? (The result of any execution is the same as if the operations of all the processors were executed in some sequential order, and the operations of each individual processor appear in this sequence in the order specified by its program).
What is a memory barrier? (A memory barrier, also known as a membar, memory fence or fence instruction, is a type of barrier instruction that causes a CPU or compiler to enforce an ordering constraint on memory operations issued before and after the barrier instruction)
Synchonization aids in Java
- CountDownLatch
- CyclicBarrier
- Phaser
- ReentrantLock
- Exchanger
- Semaphore
- LinkedTransferQueue
What is data race? (When a program contains two conflicting accesses that are not ordered by a happens-before relationship, it is said to contain a data race. Two accesses to (reads of or writes to) the same variable are said to be conflicting if at least one of the accesses is a write. But see this)
Java memory model
- A program is correctly synchronized if and only if all sequentially consistent executions are free of data races
- Correctly synchronized programs have sequentially consistent semantics. If a program is correctly synchronized, then all executions of the program will appear to be sequentially consistent
- Causality requirement for incorrectly synchronized programs: link
What is monitor in Java? (Each object in Java is associated with a monitor, which a thread can lock or unlock)
What is safe publication?
What is wait/notify?
Amdahl's law? (Speedup = 1 / (1 - p + p / n))
Dining philosophers problem (Resource hierarchy (first take lower-indexed fork), arbitrator, communication (dirty/clean forks)).
Produces/consumer problem.
Readers/writers problem.
Transactional memory
Coroutine

[⬆]** **Java:

PhantomReference, WeakReference, SoftReference, finalize(), ReferenceQueue.
How to correctly stop a thread? (Thread.interrupt())
What is Spring? (Spring Framework is an application container for Java that supplies many useful features, such as Inversion of Control, Dependency Injection, abstract data access, transaction management, and more)
- Spring is a framework for dependency injection: a design pattern that allows the developer to build very decoupled systems by injecting dependencies into classes.
- It elegantly wraps Java libraries and makes then much easier to use in your application.
- Included in the framework are implementations of commonly used patterns such as REST and MVC web framework which are predominately use by in web applications.
What is Spring-Boot?
What is Hibernate and JPA (Caches, lazy-loading)?
Garbage collection. (G1, Young/Old generation collectors combination examples: PS Scavenge/PS MarkSweep, Copy/MarkSweepCompact)
How to write benchmarks? (jmh)
What are Java 9 modularity?
What is OSGI? (Specification describes a modular system and a service platform for the Java programming language that implements a complete and dynamic component model. Each bundle has its own classpath. Dependency hell avoidance. META-INF/MANIFEST. MF contains OSGI-info)
Serializable / Externalizable
What is a servlet (versions of servlet api, Servlet 4.0)?
What is a servlet filter? How to implement GZipFilter? (ResponseWrapper)
What is generics and PECS (producer extends and consumer super)?
What is the difference between <?>, <Object>, <? extends Object> and no generic type? link1 link2
Explain method signature for Collections.max(...), Collections.fill(...), Collections.copy(...), Collections.sort(...)
Why are arrays covariant but generics are invariant? link
Major specs: JAX-RS, JAX-WS, JMS, JAXB, XSLT, XPATH, JNDI, JMX, JDBC, XML(SAX, DOM, StAX)
Performance Diagnostic Methodology

[⬆]** **General Questions:

Polymorphism (Variable of type Shape could refer to an object of type Square, Circle... Ability of a function to handle objects of many types)
Encapsulation (Packing of data and functions into a single component)
Virtual function (Overridable function)
Virtual method table
Dynamic binding (Actual method implementation invoked is determined at run time based on the class of the object, not the type of the variable or expression)
How does garbage collector work? (Mark and sweep: mark: traverse object graph starting from root objects, sweep: garbage collect unmarked objects. Optimizations: young/old generations, incremental mark and sweep)
Tail recursion (A tail call is a subroutine call performed as the final action of a procedure)
Semantic versioning

[⬆]** **WEB:

WEB security vulnerabilities (XSS, CSRF, session fixation, SQL injection, man-in-the-middle, buffer overflow)
CSRF prevention (CSRF-token)
What is JSONP, CORS? (A communication technique used in JavaScript programs running in web browsers to request data from a server in a different domain, something prohibited by typical web browsers because of the same-origin policy)
HTTPS negotiation steps.
What is HTTP Strict Transport Security (HSTS)? (Prevents Man in the Middle attacks)
Browser-server communication methods: WebSocket, EventSource, Comet(Polling, Long-Polling, Streaming)
Character encoding
What is role-based access control and access control list?
What is session and persistent cookies, sessionStorage and localStorage?
How to implement remember-me? (http://jaspan.com/improved_persistent_login_cookie_best_practice)
Authentication using cookies, JWT (JSON Web Tokens).

[⬆]** **SQL:

SQL join types (inner join, left/right outer join, full outer join, cross join)

)

SQL normal forms
1. The domain of each attribute contains only atomic values, and the value of each attribute contains only a single value from that domain
2. No non-prime attribute in the table is functionally dependent on a proper subset of any candidate key
3. Every non-prime attribute is non-transitively dependent on every candidate key in the table. BCNF.Every non-trivial functional dependency in the table is a dependency on a superkey.)
Isolation levels and Anomalies

Isolation_level\Anomaly

Lost_update (because of rollback)

Dirty_read

Non_repeatable_reads second_lost_update

Phantoms

Write_skew

Read Uncommitted

may occur

Read Committed

may occur

Repeatable Read

may occur

Snapshot

may occur

Serializable

[⬆]** **NoSQL:

Types of NoSQL databases?
- Document Stores (MongoDB, Couchbase)
- Key-Value Stores (Redis, Volgemort)
- Column Stores (Cassandra)
- Graph Stores (Neo4j, Giraph)

[⬆]** **Transactions:

ACID
2-phase commit protocol
3-phase commit protocol
What is pessimistic / optimistic locking?

[⬆]** **Scalability:

Horizontal and vertical scaling.
How to scale database? (Data partitioning, sharding(vertical/horizontal), replication(master-slave, master-master)).
Denormalization.
What is synchronous multimaster replication? (Each server can accept write requests, and modified data is transmitted from the original server to every other server before each transaction commits)
What is asynchronous multimaster replication? (Each server works independently, and periodically communicates with the other servers to identify conflicting transactions. The conflicts can be resolved by users or conflict resolution rules)
When to use messaging queue?
MongoDB, Redis.
Hadoop basics.

[⬆]** **Load balancing:

sticky/non-sticky sessions
Sticky sessions vs storing sessions in Redis.

[⬆]** **Cloud computing:

What is cloud computing? (Cloud computing platform is a fully automated server platform that allows users to purchase, remotely create, dynamically scale, and administer system)
Amazon web services
Google Cloud Platform
Microsoft Azure

[⬆]** **Distributed:

Consensus
Raft (In Search of an Understandable Consensus Algorithm)
Paxos
What is CAP theorem? Illustrated proof. CAP-FAQ (It is impossible for a distributed computer system to simultaneously provide all three of the following guarantees: consistency, availability, partition tolerance). Gilbert and Lynch's paper. "Please stop calling databases CP or AP").

What is map-reduce? (Word count example)
Sharding counters.
Distributed software:
- Distributed streaming platforms: kafka
- Distributed key-value store: zookeeper, etcd, Consul
- Map-reduce: hadoop, spark
- Distributed file system: hbase
- Cluster management: kubernetes, docker-swarm, mesos
Herlihy's consensus hierarchy. Every shared object can be assigned a consensus number, which is the maximum number of processes for which the object can solve wait-free consensus in an asynchronous system.

1 Read-write registers
2 Test-and-set, swap, fetch-and-add, queue, stack
⋮ ⋮
∞ Augmented queue, compare-and-swap, sticky byte

Consistency models:
Consensus number. Maximum number of threads for which objects of the class can solve consensus problem.
Logical clock
Vector clock

[⬆]** **Cache:

What is write-through and write-behind caching? (write-through (synchronous), write-behind (asynchronous))
HTTP cache options?

[⬆]** **Networking:

OSI model (Physical, Data link, Network, Transport, Session, Presentation, Application)
Multithreading vs select
Switch, hub, router
TCP congestion
TCP back-pressure

[⬆]** **Operating system:

What is memory mapped file and its benefits?
Interprocess communication methods. (Pipes, Events, Mailboxes/Ports (can be implemented by using shared memory and semaphores), Direct Message Passing).
Virtual memory organization.
Process scheduler.

[⬆]** **Compilers:

[⬆]** **C++:

C++ standard
Memory model
Data race. When an evaluation of an expression writes to a memory location and another evaluation reads or modifies the same memory location, the expressions are said to conflict. A program that has two conflicting evaluations has a data race unless
- both evaluations execute on the same thread or in the same signal handler, or
- both conflicting evaluations are atomic operations (see std::atomic), or
- one of the conflicting evaluations happens-before another (see std::memory_order)
If a data race occurs, the behavior of the program is undefined.
SFINAE 1
[PImpl] https://en.cppreference.com/w/cpp/language/pimpl

[⬆]** **Javascript:

this keyword
How prototypes work?
inheritance
differences between == and === (http://dorey.github.io/JavaScript-Equality-Table/)
closures
recursion
What is MVC, MVP, MVVM?
What is promise?
What is event bubbling and capturing? (target.addEventListener(type, listener[, useCapture]))
What is AMD(Asynchronous Module Design) and CommonJS?
What is jQuery?

[⬆]** **Python:

Slice notation

[⬆]** **Go:

[⬆]** **Codewriting:

Implement binary search

int binarySearch(int[] a, int fromInclusive, int toExclusive, int key) {
    int low = fromInclusive;
    int high = toExclusive - 1;
    while (low <= high) {
        int mid = (low + high) >>> 1;
        int midVal = a[mid];
        if (midVal < key)
            low = mid + 1;
        else if (midVal > key)
            high = mid - 1;
        else
            return mid; // key found
    }
    return -(low + 1); // key not found
}

Implement quick sort

void qSort(int[] a, int fromInclusive, int toInclusive) {
    int i = fromInclusive;
    int j = toInclusive;
    if (i >= j) return;
    int separator = a[i + random.nextInt(j - i + 1)];
    do {
        while (a[i] < separator) ++i;
        while (a[j] > separator) --j;
        if (i > j) break;
        int t = a[i];
        a[i] = a[j];
        a[j] = t;
        ++i;
        --j;
    } while (i <= j);
    qSort(a, fromInclusive, j);
    qSort(a, i, toInclusive);
}

[⬆]** **Functional programming:

Referential transparency
What is Monad?

[⬆]** **Reactive programming:

The Reactive Manifesto (responsive, resilient, elastic, message driven)
Reactive extensions
What is asynchronous and non-blocking? link

[⬆]** **Git:

Git workflow? (Master: production-ready state; Develop: latest delivered development changes for the next release; Feature Branches; Release Branches; Hotfixes)

http://nvie.com/posts/a-successful-git-branching-model/

What is a rebase?

[⬆]** **DevOps:

What is Blue-green Deployment, Canary release, A/B testing? link
What is Docker?

[⬆]** **QA:

What is unit test? (A test that purely tests a single unit of functionality)
What is component test?
What is integration test? (Examine several parts of a system to make sure that when integrated, these parts behave as expected)
What is user acceptance test? BDD?
Unit tests advantages?
Types of tests: acceptance testing, functional testing, smoke testing, regression testing, unit testing, integration testing, stress testing, (Load, Performance, Sanity, Stability, Security, Feature, Progression, Installation, Business).
Differences between stub and mock? (A stub is a test double with preprogrammed behavior. Mocks are stubs with preprogrammed expectations)
Selenium tests and webdriver.
How to test multithreading code?
What is Consumer Driven Contract? link
Types of tests

[⬆]** **Agile:

What is Agile? (http://agilemanifesto.org/principles.html)
- Individuals and interactions over Processes and tools
- Working software over Comprehensive documentation
- Customer collaboration over Contract negotiation
- Responding to change over Following a plan
What is Scrum? (Roles: product owner, development team, scrum master. Events: sprint)
What are the differences between Scrum and Waterfall? ( http://www.leanagiletraining.com/agile/waterfall-versus-scrum-how-do-they-compare/)
What is XP? ()
What is Kanban?
What is Lean development?

[⬆]** **Algorithms:

What Ο(n), Ω(n), Θ(n)?
What is NP, NP-completeness, NP-hardness with examples?

[⬆]** **Other:

How to find memory leak. (Memory snapshot diff).
Profiling: sampling and instrumentation.
Regular expressions. (Examples)
What are your goals to work in our company? (3 categories: professional, financial, social)
What is virtualization?
What is total/partial order?
How to work with legacy code? (http://programmers.stackexchange.com/a/122024)

[⬆]** **Machine learning:

Bayes' theorem:

![equation](http://latex.codecogs.com/svg.latex?\inline&space; \fn_cs&space; P(A|B)&space; =&space; \dfrac{P(B|A)\times&space; P(A)}{P(B)}, P(B)&space; =&space; \sum\limits_{i}{P(Ai)\times&space; P(B|Ai)})

[⬆]** **Big Data:

[⬆]** **Image processing:

[⬆]** **Cryptography:

select 2 primes: p,q
n = p*q
phi(n) = (p-1)*(q-1)
select 1<e<phi(n), gcd(e,phi(n))=1
d=e^-1 mod phi(n)
(e,n) - public key
(d,n) - private key
c = m^e mod n
m = c^d mod n = m^(e*d) mod n = m^(e*d mod phi(n)) mod n = m

[⬆]** **Security:

What is OpenID and OAuth2.0 and OpenID Connect?
Four main actors in an OAuth system (clients, resource owners, authorization servers, and protected resources)
What is access_token, refresh_token, SAML token, JWT token?
Sticky session vs Session Replication.
What is hash salt?
What is Federated Authentication ?
What is CSP and SRI hash ?
What is Clickjacking and Cursorjacking ? How to prevent it ?

[⬆]** **Android:

[⬆]** **Books:

C++ programming

Java programming

Effective Java (3rd Edition)

Algorithms

Concurrent programming

Statistics

Machine Learning

Digital Signal Processing

Digital Signal Processing: A Practical Approach, 2nd Edition

Digital Image Processing

Other

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Programming Languages/Frameworks/Platforms

Android

AngularJS

Angular

BackboneJS

C++

C

C#

.NET

Clojure

CSS

Cucumber

Django

Docker

Elastic

EmberJS

Erlang

Golang

GraphQl

HTML

Ionic

iOS

Java

JavaScript

jQuery

Front-end build tools

KnockoutJS

Less

Lisp

NodeJS

Objective-C

PHP

Python

Ruby on Rails

ReactJS

Ruby

Rust

Sass

Scala

SharePoint

Shell

Spark

Swift

Vue.js

WordPress

TypeScript

Database technologies

Cassandra

Microsoft Access

MongoDB

MySQL

Neo4j

Oracle

Postgres

SQL

SQLite

Caching technologies

Memcached

Redis

OS

Linux

Windows

DevOps

Algorithms

Blockchain

Coding exercises

Comprehensive lists

Design Patterns

Data structures

Networks

Security

Data Science

FULL-STACK DEVELOPER INTERVIEW QUESTIONS AND ANSWERS

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