---
title: "Denial of Service (DoS) - Glossary | MDN"
chunk: 1/3
source: "https://developer.mozilla.org/en-US/docs/Glossary/Denial_of_Service"
category: "reference"
tags: "web, html, css, javascript, documentation"
date_saved: "2026-05-05T05:29:30.760889+00:00"
instance: "kb-cron"
---

  * [Skip to main content](https://developer.mozilla.org/en-US/docs/Glossary/Denial_of_Service#content)
  * [Skip to search](https://developer.mozilla.org/en-US/docs/Glossary/Denial_of_Service#search)

[ MDN ](https://developer.mozilla.org/en-US/)
HTML
[HTML: Markup language](https://developer.mozilla.org/en-US/docs/Web/HTML) 

HTML reference
    
  * [Elements](https://developer.mozilla.org/en-US/docs/Web/HTML/Reference/Elements)
  * [Global attributes](https://developer.mozilla.org/en-US/docs/Web/HTML/Reference/Global_attributes)
  * [Attributes](https://developer.mozilla.org/en-US/docs/Web/HTML/Reference/Attributes)
  * [See all…](https://developer.mozilla.org/en-US/docs/Web/HTML/Reference "See all HTML references")

HTML guides
    
  * [Responsive images](https://developer.mozilla.org/en-US/docs/Web/HTML/Guides/Responsive_images)
  * [HTML cheatsheet](https://developer.mozilla.org/en-US/docs/Web/HTML/Guides/Cheatsheet)
  * [Date & time formats](https://developer.mozilla.org/en-US/docs/Web/HTML/Guides/Date_and_time_formats)
  * [See all…](https://developer.mozilla.org/en-US/docs/Web/HTML/Guides "See all HTML guides")

Markup languages
    
  * [SVG](https://developer.mozilla.org/en-US/docs/Web/SVG)
  * [MathML](https://developer.mozilla.org/en-US/docs/Web/MathML)
  * [XML](https://developer.mozilla.org/en-US/docs/Web/XML)

CSS
[CSS: Styling language](https://developer.mozilla.org/en-US/docs/Web/CSS) 

CSS reference
    
  * [Properties](https://developer.mozilla.org/en-US/docs/Web/CSS/Reference/Properties)
  * [Selectors](https://developer.mozilla.org/en-US/docs/Web/CSS/Reference/Selectors)
  * [At-rules](https://developer.mozilla.org/en-US/docs/Web/CSS/Reference/At-rules)
  * [Values](https://developer.mozilla.org/en-US/docs/Web/CSS/Reference/Values)
  * [See all…](https://developer.mozilla.org/en-US/docs/Web/CSS/Reference "See all CSS references")

CSS guides
    
  * [Box model](https://developer.mozilla.org/en-US/docs/Web/CSS/Guides/Box_model/Introduction)
  * [Animations](https://developer.mozilla.org/en-US/docs/Web/CSS/Guides/Animations/Using)
  * [Flexbox](https://developer.mozilla.org/en-US/docs/Web/CSS/Guides/Flexible_box_layout/Basic_concepts)
  * [Colors](https://developer.mozilla.org/en-US/docs/Web/CSS/Guides/Colors/Applying_color)
  * [See all…](https://developer.mozilla.org/en-US/docs/Web/CSS/Guides "See all CSS guides")

Layout cookbook
    
  * [Column layouts](https://developer.mozilla.org/en-US/docs/Web/CSS/How_to/Layout_cookbook/Column_layouts)
  * [Centering an element](https://developer.mozilla.org/en-US/docs/Web/CSS/How_to/Layout_cookbook/Center_an_element)
  * [Card component](https://developer.mozilla.org/en-US/docs/Web/CSS/How_to/Layout_cookbook/Card)
  * [See all…](https://developer.mozilla.org/en-US/docs/Web/CSS/How_to/Layout_cookbook)

JavaScriptJS
[JavaScript: Scripting language](https://developer.mozilla.org/en-US/docs/Web/JavaScript) 

JS reference
    
  * [Standard built-in objects](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects)
  * [Expressions & operators](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Operators)
  * [Statements & declarations](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Statements)
  * [Functions](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Functions)
  * [See all…](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference "See all JavaScript references")

JS guides
    
  * [Control flow & error handing](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Guide/Control_flow_and_error_handling)
  * [Loops and iteration](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Guide/Loops_and_iteration)
  * [Working with objects](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Guide/Working_with_objects)
  * [Using classes](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Guide/Using_classes)
  * [See all…](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Guide "See all JavaScript guides")

Web APIs
[Web APIs: Programming interfaces](https://developer.mozilla.org/en-US/docs/Web/API) 

Web API reference
    
  * [File system API](https://developer.mozilla.org/en-US/docs/Web/API/File_System_API)
  * [Fetch API](https://developer.mozilla.org/en-US/docs/Web/API/Fetch_API)
  * [Geolocation API](https://developer.mozilla.org/en-US/docs/Web/API/Geolocation_API)
  * [HTML DOM API](https://developer.mozilla.org/en-US/docs/Web/API/HTML_DOM_API)
  * [Push API](https://developer.mozilla.org/en-US/docs/Web/API/Push_API)
  * [Service worker API](https://developer.mozilla.org/en-US/docs/Web/API/Service_Worker_API)
  * [See all…](https://developer.mozilla.org/en-US/docs/Web/API "See all Web API guides")

Web API guides
    
  * [Using the Web animation API](https://developer.mozilla.org/en-US/docs/Web/API/Web_Animations_API/Using_the_Web_Animations_API)
  * [Using the Fetch API](https://developer.mozilla.org/en-US/docs/Web/API/Fetch_API/Using_Fetch)
  * [Working with the History API](https://developer.mozilla.org/en-US/docs/Web/API/History_API/Working_with_the_History_API)
  * [Using the Web speech API](https://developer.mozilla.org/en-US/docs/Web/API/Web_Speech_API/Using_the_Web_Speech_API)
  * [Using web workers](https://developer.mozilla.org/en-US/docs/Web/API/Web_Workers_API/Using_web_workers)

All
[All web technology](https://developer.mozilla.org/en-US/docs/Web) 

Technologies
    
  * [Accessibility](https://developer.mozilla.org/en-US/docs/Web/Accessibility)
  * [HTTP](https://developer.mozilla.org/en-US/docs/Web/HTTP)
  * [URI](https://developer.mozilla.org/en-US/docs/Web/URI)
  * [Web extensions](https://developer.mozilla.org/en-US/docs/Mozilla/Add-ons/WebExtensions)
  * [WebAssembly](https://developer.mozilla.org/en-US/docs/WebAssembly)
  * [WebDriver](https://developer.mozilla.org/en-US/docs/Web/WebDriver)
  * [See all…](https://developer.mozilla.org/en-US/docs/Web "See all web technology references")

Topics
    
  * [Media](https://developer.mozilla.org/en-US/docs/Web/Media)
  * [Performance](https://developer.mozilla.org/en-US/docs/Web/Performance)
  * [Privacy](https://developer.mozilla.org/en-US/docs/Web/Privacy)
  * [Security](https://developer.mozilla.org/en-US/docs/Web/Security)
  * [Progressive web apps](https://developer.mozilla.org/en-US/docs/Web/Progressive_web_apps)

Learn
[Learn web development](https://developer.mozilla.org/en-US/docs/Learn_web_development) 

Frontend developer course
    
  * [Getting started modules](https://developer.mozilla.org/en-US/docs/Learn_web_development/Getting_started)
  * [Core modules](https://developer.mozilla.org/en-US/docs/Learn_web_development/Core)
  * [MDN Curriculum](https://developer.mozilla.org/en-US/curriculum/)
  * [Check out the video course from Scrimba, our partner](https://scrimba.com/frontend-path-c0j?via=mdn-learn-navbar)

Learn HTML
    
  * [Structuring content with HTML module](https://developer.mozilla.org/en-US/docs/Learn_web_development/Core/Structuring_content)

Learn CSS
    
  * [CSS styling basics module](https://developer.mozilla.org/en-US/docs/Learn_web_development/Core/Styling_basics)
  * [CSS layout module](https://developer.mozilla.org/en-US/docs/Learn_web_development/Core/CSS_layout)

Learn JavaScript
    
  * [Dynamic scripting with JavaScript module](https://developer.mozilla.org/en-US/docs/Learn_web_development/Core/Scripting)

Tools
Discover our tools 
  * [Playground](https://developer.mozilla.org/en-US/play)
  * [HTTP Observatory](https://developer.mozilla.org/en-US/observatory)

  * [Border-image generator](https://developer.mozilla.org/en-US/docs/Web/CSS/Guides/Backgrounds_and_borders/Border-image_generator)
  * [Border-radius generator](https://developer.mozilla.org/en-US/docs/Web/CSS/Guides/Backgrounds_and_borders/Border-radius_generator)
  * [Box-shadow generator](https://developer.mozilla.org/en-US/docs/Web/CSS/Guides/Backgrounds_and_borders/Box-shadow_generator)
  * [Color format converter](https://developer.mozilla.org/en-US/docs/Web/CSS/Guides/Colors/Color_format_converter)
  * [Color mixer](https://developer.mozilla.org/en-US/docs/Web/CSS/Guides/Colors/Color_mixer)
  * [Shape generator](https://developer.mozilla.org/en-US/docs/Web/CSS/Guides/Shapes/Shape_generator)

About
Get to know MDN better 
  * [About MDN](https://developer.mozilla.org/en-US/about)
  * [Advertise with us](https://developer.mozilla.org/en-US/advertising)

  * [Community](https://developer.mozilla.org/en-US/community)
  * [MDN on GitHub](https://github.com/mdn)

[Blog](https://developer.mozilla.org/en-US/blog/)
  1. [Glossary](https://developer.mozilla.org/en-US/docs/Glossary)
  2. [Denial of Service (DoS)](https://developer.mozilla.org/en-US/docs/Glossary/Denial_of_Service)

# Denial of Service (DoS)
**Denial of Service** (DoS) is a category of network attack that consumes available [server](https://developer.mozilla.org/en-US/docs/Glossary/Server) resources, typically by flooding the server with requests. The server is then sluggish or unavailable for legitimate users.
Computers have limited resources, for example computation power or memory. When these are exhausted, the program can freeze or crash, making it unavailable. A DoS attack consists of various techniques to exhaust these resources and make a server or a network unavailable to legitimate users, or at least make the server perform sluggishly.
There are also [Distributed Denial of Service (DDoS)](https://developer.mozilla.org/en-US/docs/Glossary/Distributed_Denial_of_Service) attacks in which a multitude of servers are used to exhaust the computing capacity of an attacked computer.
## In this article
  * [Types of DoS attack](https://developer.mozilla.org/en-US/docs/Glossary/Denial_of_Service#types_of_dos_attack)
  * [See also](https://developer.mozilla.org/en-US/docs/Glossary/Denial_of_Service#see_also)

##  [Types of DoS attack](https://developer.mozilla.org/en-US/docs/Glossary/Denial_of_Service#types_of_dos_attack)
DoS attacks are more of a category than a particular kind of attack. Here is a non-exhaustive list of DoS attack types:
  * bandwidth attack
  * service request flood
  * SYN flooding attack
  * ICMP flood attack
  * peer-to-peer attack
  * permanent DoS attack
  * application level flood attack

##  [See also](https://developer.mozilla.org/en-US/docs/Glossary/Denial_of_Service#see_also)
  * [Denial-of-service attack](https://en.wikipedia.org/wiki/Denial-of-service_attack) on Wikipedia
  * [Denial of Service](https://owasp.org/www-community/attacks/Denial_of_Service) on OWASP