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A content delivery network, or content distribution network (CDN), is a geographically distributed network of
proxy server In computer networking A computer network is a set of computer A computer is a machine that can be programmed to carry out sequences of arithmetic or logical operations automatically. Modern computers can perform generic sets of ...

proxy server
s and their
data center A data center (American English American English (AmE, AE, AmEng, USEng, en-US), sometimes called United States English or U.S. English, is the set of varieties of the English language native to the United States. Currently, American Eng ...
s. The goal is to provide high availability and performance by distributing the service spatially relative to
end user In product development, an end user (sometimes end-user) is a person who ultimately uses or is intended to ultimately use a product. The end user stands in contrast to users who support or maintain the product, such as sysop A sysop (; an abbre ...
s. CDNs came into existence in the late 1990s as a means for alleviating the performance bottlenecks of the Internet as the Internet was starting to become a mission-critical medium for people and enterprises. Since then, CDNs have grown to serve a large portion of the Internet content today, including web objects (text, graphics and scripts), downloadable objects (media files, software, documents), applications (
e-commerce E-commerce (electronic commerce) is the activity of electronically buying or selling of Product (business), products on online services or over the Internet. E-commerce draws on technologies such as mobile commerce, electronic funds transfer, su ...

e-commerce
, portals),
live streaming Livestreaming is online streaming media Streaming media is multimedia that is delivered and consumed in a continuous manner from a source, with little or no intermediate storage in network elements. ''Streaming'' refers to the delivery met ...
media, on-demand streaming media, and
social media Social media are interactive technologies that facilitate the creation Creation may refer to: Religion * Creation ''ex nihilo'', the concept that matter was created by God out of nothing * Creation myth A creation myth (or cosmogonic myth) ...

social media
sites. CDNs are a
layer Layer or layered may refer to: Arts, entertainment, and media Music Albums * ''Layers'' (Kungs album) *Layers (Les McCann album), ''Layers'' (Les McCann album) *Layers (Royce da 5'9" album), ''Layers'' (Royce da 5'9" album) Songs *"Layers", the ...
in the internet ecosystem. Content owners such as media companies and e-commerce vendors pay CDN operators to deliver their content to their end users. In turn, a CDN pays
Internet service provider An Internet service provider (ISP) is an organization that provides a myriad of services for accessing, using, or participating in the Internet The Internet (or internet) is the global system of interconnected computer networks that ...
s (ISPs), carriers, and network operators for hosting its servers in their data centers. CDN is an umbrella term spanning different types of content delivery services:
video streaming Streaming media is multimedia that is delivered and consumed in a continuous manner from a source, with little or no intermediate storage in network elements. ''Streaming'' refers to the delivery method of content, rather than the content its ...
, software downloads, web and mobile content acceleration, licensed/managed CDN, transparent caching, and services to measure CDN performance, load balancing, Multi CDN switching and analytics and cloud intelligence. CDN vendors may cross over into other industries like security, with
DDoS In computing Computing is any goal-oriented activity requiring, benefiting from, or creating computing machinery. It includes the study and experimentation of algorithmic processes and development of both computer hardware , hardware and sof ...
protection and
web application firewall A web application firewall (WAF) is a specific form of application firewall that filters, monitors, and blocks HTTP network traffic, traffic to and from a web application, web service. By inspecting HTTP traffic, it can prevent attacks exploiti ...
s (WAF), and WAN optimization.


Technology

CDN nodes are usually deployed in multiple locations, often over multiple
Internet backbone The Internet backbone may be defined by the principal data routes between large, strategically interconnected computer network A computer network is a set of s sharing resources located on or provided by . The computers use common s over ...
s. Benefits include reducing bandwidth costs, improving page load times, or increasing global availability of content. The number of nodes and servers making up a CDN varies, depending on the architecture, some reaching thousands of nodes with tens of thousands of servers on many remote
points of presence A point of presence (PoP) is an artificial demarcation point In telephony Telephony ( ) is the field of technology involving the development, application, and deployment of telecommunication Telecommunication is the transmission of in ...
(PoPs). Others build a global network and have a small number of geographical PoPs. Requests for content are typically algorithmically directed to nodes that are optimal in some way. When optimizing for performance, locations that are best for serving content to the user may be chosen. This may be measured by choosing locations that are the fewest
hops Hops are the flower A flower, sometimes known as a bloom or blossom Cherry blossoms in Paris in full bloom. In botany, blossoms are the flowers of stone fruit fruit tree, trees (genus ''Prunus'') and of some other plants with a similar ...
, the lowest number of network seconds away from the requesting client, or the highest availability in terms of server performance (both current and historical), so as to optimize delivery across local networks. When optimizing for cost, locations that are least expensive may be chosen instead. In an optimal scenario, these two goals tend to align, as edge servers that are close to the end user at the edge of the network may have an advantage in performance or cost. Most CDN providers will provide their services over a varying, defined, set of PoPs, depending on the coverage desired, such as United States, International or Global, Asia-Pacific, etc. These sets of PoPs can be called "edges", "edge nodes", "edge servers", or "edge networks" as they would be the closest edge of CDN assets to the end user.


Security and privacy

CDN providers profit either from direct fees paid by
content provider A value-added service (VAS) is a popular telecommunications industry{{cite web, url=http://www.prweb.com/releases/2013/11/prweb11284640.htm, title=Global Mobile Value Added Services (VAS) Market: Worldwide Industry Share, Investment Trends, Growth, ...
s using their network, or profit from the user analytics and tracking data collected as their scripts are being loaded onto customer's websites inside their browser origin. As such these services are being pointed out as potential privacy intrusion for the purpose of
behavioral targeting Targeted advertising is a form of advertising Advertising is a marketing communication that employs an openly sponsored, non-personal message to promote or sell a product, service or idea.William J. Stanton. ''Fundamentals of Marketing''. ...
and solutions are being created to restore single-origin serving and caching of resources. CDNs serving JavaScript have also been targeted as a way to inject malicious content into pages using them.
Subresource IntegritySubresource Integrity or SRI is a W3C recommendation to provide a method to protect website delivery. Specifically, it validates assets served by a third party, such as a content delivery network (CDN). This ensures these assets have not been comprom ...
mechanism was created in response to ensure that the page loads a script whose content is known and constrained to a hash referenced by the website author.


Content networking techniques

The Internet was designed according to the
end-to-end principle The end-to-end principle is a design framework in computer network A computer network is a group of computers that use a set of common communication protocols over digital signal, digital interconnections for the purpose of sharing resource ...
. This principle keeps the core network relatively simple and moves the intelligence as much as possible to the network end-points: the hosts and clients. As a result, the core network is specialized, simplified, and optimized to only forward data packets. Content Delivery Networks augment the end-to-end transport network by distributing on it a variety of intelligent applications employing techniques designed to optimize content delivery. The resulting tightly integrated overlay uses web caching, server-load balancing, request routing, and content services.
Web cache A Web cache (or HTTP cache) is a system for optimizing the World Wide Web The World Wide Web (WWW), commonly known as the Web, is an information system An information system (IS) is a formal, sociotechnical Sociotechnical systems ( ...
s store popular content on servers that have the greatest demand for the content requested. These shared network appliances reduce bandwidth requirements, reduce server load, and improve the client response times for content stored in the cache. Web caches are populated based on requests from users (pull caching) or based on preloaded content disseminated from content servers (push caching). Server-load balancing uses one or more techniques including service-based (global load balancing) or hardware-based (i.e. layer 4–7 switches, also known as a web switch, content switch, or multilayer switch) to share traffic among a number of servers or web caches. Here the switch is assigned a single virtual
IP address An Internet Protocol address (IP address) is a numerical label such as that is connected to a computer network A computer network is a set of s sharing resources located on or provided by . The computers use common s over to communi ...
. Traffic arriving at the switch is then directed to one of the real
web servers A web server is computer software and underlying hardware that accepts requests via HTTP The Hypertext Transfer Protocol (HTTP) is an application layer An application layer is an abstraction layer that specifies the shared communications ...
attached to the switch. This has the advantage of balancing load, increasing total capacity, improving scalability, and providing increased reliability by redistributing the load of a failed web server and providing server health checks. A content cluster or service node can be formed using a layer 4–7 switch to balance load across a number of servers or a number of web caches within the network. Request routing directs client requests to the content source best able to serve the request. This may involve directing a client request to the service node that is closest to the client, or to the one with the most capacity. A variety of algorithms are used to route the request. These include Global Server Load Balancing, DNS-based request routing, Dynamic metafile generation, HTML rewriting, and
anycast Anycast is a network addressing In computing, an address space defines a range of discrete addresses, each of which may correspond to a network host, peripheral device, disk sector, a computer data storage, memory cell or other logical or physical ...

anycast
ing. Proximity—choosing the closest service node—is estimated using a variety of techniques including reactive probing, proactive probing, and connection monitoring. CDNs use a variety of methods of content delivery including, but not limited to, manual asset copying, active web caches, and global hardware load balancers.


Content service protocols

Several protocol suites are designed to provide access to a wide variety of content services distributed throughout a content network. The Internet Content Adaptation Protocol (ICAP) was developed in the late 1990s to provide an open standard for connecting application servers. A more recently defined and robust solution is provided by the
Open Pluggable Edge Services Open or OPEN may refer to: citizen Citizenship is the status of a person recognized under the law of a country A country is a distinct territory, territorial body or political entity. It is often referred to as the land of an individu ...
(OPES) protocol. This architecture defines OPES service applications that can reside on the OPES processor itself or be executed remotely on a Callout Server.
Edge Side IncludesEdge Side Includes or ESI is a small markup language In computer text processing, a markup language is a system for annotation, annotating a document in a way that is Syntax (logic), syntactically distinguishable from the text, meaning when the do ...
or ESI is a small markup language for edge level dynamic web content assembly. It is fairly common for websites to have generated content. It could be because of changing content like catalogs or forums, or because of the personalization. This creates a problem for caching systems. To overcome this problem, a group of companies created ESI.


Peer-to-peer CDNs

In ''
peer-to-peer Peer-to-peer (P2P) computing or networking is a distributed application Distributed computing is a field of computer science that studies distributed systems. A ''distributed system'' is a system whose components are located on different co ...

peer-to-peer
(P2P)'' content-delivery networks, clients provide resources as well as use them. This means that unlike client–server systems, the content centric networks can actually perform better as more users begin to access the content (especially with protocols such as
Bittorrent BitTorrent (abbreviated to BT) is a communication protocol Protocol may refer to: Sociology and politics * Protocol (politics) Protocol originally (in Late Middle English, c. 15th century) meant the minutes or logbook taken at a meeting, upon ...

Bittorrent
that require users to share). This property is one of the major advantages of using P2P networks because it makes the setup and running costs very small for the original content distributor.


Private CDNs

If content owners are not satisfied with the options or costs of a commercial CDN service, they can create their own CDN. This is called a private CDN. A private CDN consists of PoPs (points of presence) that are only serving content for their owner. These PoPs can be caching servers, reverse proxies or application delivery controllers. It can be as simple as two caching servers, or large enough to serve petabytes of content. Large content distribution networks may even build and set up their own private network to distribute copies of content across cache locations. Such private networks are usually used in conjunction with public networks as a backup option in case the capacity of private network is not enough or there is a failure which leads to capacity reduction. Since the same content has to be distributed across many locations, a variety of
multicast In computer networking A computer network is a set of computer A computer is a machine that can be programmed to carry out sequences of arithmetic or logical operations automatically. Modern computers can perform generic sets of ...

multicast
ing techniques may be used to reduce bandwidth consumption. Over private networks, it has also been proposed to select multicast trees according to network load conditions to more efficiently utilize available network capacity.


CDN trends


Emergence of telco CDNs

The rapid growth of
streaming video Streaming media is multimedia Multimedia is a form of communication that combines different such as , , , , or into a single interactive presentation, in contrast to traditional mass media which ...
traffic uses large
capital expenditures Capital expenditure or capital expense (capex or CAPEX) is the money an organization or corporate entity spends to buy, maintain, or improve its fixed assets, such as buildings, vehicles, equipment, or land. It is considered a capital expenditure ...
by broadband providers in order to meet this demand and to retain subscribers by delivering a sufficiently good
quality of experienceQuality of experience (QoE) is a measure of the delight or annoyance of a customer's experiences with a service (e.g., web browsing, phone call, TV broadcast).Qualinet White Paper on Definitions of Quality of Experience (2012). European Network on Qu ...
. To address this,
telecommunications service provider A telecommunications service provider (TSP) is a type of communications service provider A telecommunications service provider (TSP) is a type of communications service provider that has traditionally provided telephone A telephone is ...
s (TSPs) have begun to launch their own content delivery networks as a means to lessen the demands on the network backbone and to reduce infrastructure investments.


Telco CDN advantages

Because they own the networks over which video content is transmitted, telco CDNs have advantages over traditional CDNs. They own the
last mile The last mile or last kilometer is a phrase widely used in the telecommunication Telecommunication is the transmission of information Information can be thought of as the resolution of uncertainty; it answers the question of "What an e ...
and can deliver content closer to the end-user because it can be cached deep in their networks. This deep caching minimizes the
distance Distance is a numerical measurement Measurement is the quantification (science), quantification of variable and attribute (research), attributes of an object or event, which can be used to compare with other objects or events. The scope and ...
that video data travels over the general Internet and delivers it more quickly and reliably. Telco CDNs also have a built-in cost advantage since traditional CDNs must lease bandwidth from them and build the operator's margin into their own cost model. In addition, by operating their own content delivery infrastructure, telco operators have better control over the utilization of their resources. Content management operations performed by CDNs are usually applied without (or with very limited) information about the network (e.g., topology, utilization etc.) of the telco-operators with which they interact or have business relationships. These pose a number of challenges for the telco-operators which have a limited sphere of actions in face of the impact of these operations on the utilization of their resources. In contrast, the deployment of telco-CDNs allow operators to implement their own content management operations,D. Tuncer, M. Charalambides, R. Landa, G. Pavlou, “More Control Over Network Resources: an ISP Caching Perspective,” proceedings of IEEE/IFIP Conference on Network and Service Management (CNSM), Zurich, Switzerland, October 2013.M. Claeys, D. Tuncer, J. Famaey, M. Charalambides, S. Latre, F. De Turck, G. Pavlou, “Proactive Multi-tenant Cache Management for Virtualized ISP Networks,” proceedings of IEEE/IFIP Conference on Network and Service Management (CNSM), Rio de Janeiro, Brazil, November 2014. which enables them to have better control over the utilization of their resources and, as such, provide better quality of service and experience to their end users.


Federated CDNs

In June 2011, StreamingMedia.com reported that a group of TSPs had founded an Operator Carrier Exchange (OCX) to interconnect their networks and compete more directly against large traditional CDNs like and
Limelight Networks Limelight Networks is an American company that provides a content delivery network (CDN) service, used for delivery of digital media content and software. As of February 2020, the company's network has more than 130 points-of-presence and delive ...
, which have extensive PoPs worldwide. This way, telcos are building a Federated CDN offering, which is more interesting for a
content provider A value-added service (VAS) is a popular telecommunications industry{{cite web, url=http://www.prweb.com/releases/2013/11/prweb11284640.htm, title=Global Mobile Value Added Services (VAS) Market: Worldwide Industry Share, Investment Trends, Growth, ...
willing to deliver its content to the aggregated audience of this federation. It is likely that in a near future, other telco CDN federations will be created. They will grow by enrollment of new telcos joining the federation and bringing network presence and their Internet subscriber bases to the existing ones.


Improving CDN performance using the EDNS0 option

Traditionally, CDNs have used the IP of the client's recursive DNS resolver to geo-locate the client. While this is a sound approach in many situations, this leads to poor client performance if the client uses a non-local recursive DNS resolver that is far away. For instance, a CDN may route requests from a client in India to its edge server in Singapore, if that client uses a public DNS resolver in Singapore, causing poor performance for that client. Indeed, a recent study showed that in many countries where public DNS resolvers are in popular use, the median distance between the clients and their recursive DNS resolvers can be as high as a thousand miles. In August 2011, a global consortium of leading Internet service providers led by Google announced their official implementation of the edns-client-subnet IETF Internet-Draft, which is intended to accurately localize DNS resolution responses. The initiative involves a limited number of leading DNS service providers, such as Google Public DNS, and CDN service providers as well. With the edns-client-subnet EDNS0 option, CDNs can now utilize the IP address of the requesting client's subnet when resolving DNS requests. This approach, called end-user mapping, has been adopted by CDNs and it has been shown to drastically reduce the round-trip latencies and improve performance for clients who use public DNS or other non-local resolvers. However, the use of EDNS0 also has drawbacks as it decreases the effectiveness of caching resolutions at the recursive resolvers, increases the total DNS resolution traffic, and raises a privacy concern of exposing the client's subnet.


Virtual CDN (vCDN)

Virtualization technologies are being used to deploy virtual CDNs (vCDNs) with the goal to reduce
content provider A value-added service (VAS) is a popular telecommunications industry{{cite web, url=http://www.prweb.com/releases/2013/11/prweb11284640.htm, title=Global Mobile Value Added Services (VAS) Market: Worldwide Industry Share, Investment Trends, Growth, ...
costs, and at same time, increase elasticity and decrease service delay. With vCDNs, it is possible to avoid traditional CDN limitations, such as performance, reliability and availability since virtual caches are deployed dynamically (as virtual machines or containers) in physical servers distributed across the provider geographical coverage. As the virtual cache placement is based on both the content type and server or end-user geographic location, the vCDNs have a significant impact on service delivery and network congestion.


Image Optimization and Delivery (Image CDNs)

In 2017, Addy Osmany of
Google Google LLC is an American multinational Multinational may refer to: * Multinational corporation, a corporate organization operating in multiple countries * Multinational force, a military body from multiple countries * Multinational stat ...

Google
started referring to software solutions that could integrate naturally with the
Responsive Web Design Responsive web design (RWD) or responsive design is an approach to web design Web design encompasses many different skills and disciplines in the production and maintenance of website A website (also written as web site) is a collec ...

Responsive Web Design
paradigm (with particular reference to the element) as Image CDNs. The expression referred to the ability for a web architecture to serve multiple versions of the same image through HTTP, depending on the properties of the browser requesting it, as determined by either the browser or the server-side logic. The purpose of Image CDNs was, in Google's vision, to serve high-quality images (or, better, images perceived as high-quality by the human eye) while preserving download speed, thus contributing to a great User experience (UX). Arguably, the ''Image CDN'' term was originally a misnomer, as neither
Cloudinary Cloudinary is a SaaS Software as a service (SaaS ) is a software licensing and software delivery, delivery model in which software is licensed on a subscription basis and is centrally Internet hosting service, hosted. It is sometimes referred to ...
nor Imgix (the examples quoted by Google in the 2017 guide by Addy Osmany) were, at the time, a CDN in the classical sense of the term. Shortly afterwards, though, several companies offered solutions that allowed developers to serve different versions of their graphical assets according to several strategies. Many of these solutions were built on top of traditional CDNs, such as Akamai, CloudFront, Fastly, Verizon Digital Media Services and
Cloudflare Cloudflare, Inc. is an American web infrastructure and website security company that provides content delivery network A content delivery network, or content distribution network (CDN), is a geographically distributed network of proxy servers ...
. At the same time, other solutions that already provided an image multi-serving service joined the Image CDN definition by either offering CDN functionality natively (ImageEngine) or integrating with one of the existing CDNs (Cloudinary/Akamai, Imgix/Fastly). While providing a universally agreed-on definition of what an Image CDN is may not be possible, generally speaking, an Image CDN supports the following three components: * A Content Delivery Network (CDN) for fast serving of images. * Image manipulation and optimization, either on-the-fly though
URL A Uniform Resource Locator (URL), colloquially termed a web address, is a reference to a web resource that specifies its location on a computer network A computer network is a group of computers that use a set of common communication prot ...

URL
directives, in batch mode (through manual upload of images) or fully-automatic (or a combination of these). * Device Detection (also known as Device Intelligence), i.e. the ability to determine the properties of the requesting browser and/or device through analysis of the
User-Agent In computing Computing is any goal-oriented activity requiring, benefiting from, or creating computing machinery. It includes the study and experimentation of algorithm of an algorithm (Euclid's algorithm) for calculating the greatest common ...
string,
HTTP The Hypertext Transfer Protocol (HTTP) is an application layer An application layer is an abstraction layer that specifies the shared communications protocols and Interface (computing), interface methods used by Host (network), hosts in a c ...

HTTP
Accept headers, Client-Hints or
JavaScript JavaScript (), often abbreviated JS, is a programming language A programming language is a formal language In mathematics Mathematics (from Ancient Greek, Greek: ) includes the study of such topics as quantity (number theory), ma ...

JavaScript
. The following table summarizes the current situation with the main software CDNs in this space:


Notable content delivery service providers


Free CDNs

* cdnjs *
BootstrapCDN BootstrapCDN is a public content delivery network. It enables users to load CSS, JavaScript and images remotely from its servers. Used by more than 7.9 million websites worldwide (including 30% of the top-10k websites), BootstrapCDN serves more tha ...
*
Cloudflare Cloudflare, Inc. is an American web infrastructure and website security company that provides content delivery network A content delivery network, or content distribution network (CDN), is a geographically distributed network of proxy servers ...
* JSDelivr * PageCDN *
Coral Content Distribution Network The Coral Content Distribution Network, sometimes called Coral Cache or Coral, was a free peer-to-peer 200px, A network based on the client–server model, where individual Client (computing), ''clients'' request services and resources from c ...
(Defunct)


Traditional commercial CDNs

*
Akamai Technologies Akamai Technologies, Inc. is a global content delivery networkJ. Dilley, B. Maggs, J. Parikh, H. Prokop, R. Sitaraman, and B. Weihl. (CDN), cybersecurity, and cloud service company, providing web and Internet security services. Akamai's Intell ...

Akamai Technologies
*
Amazon CloudFront Amazon CloudFront is a content delivery network (CDN) operated by Amazon Web Services. Content delivery networks provide a globally-distributed network of proxy servers that web cache, cache content, such as web videos or other bulky media, more l ...
*
Aryaka Aryaka is a SD-WAN company that provides software-defined network connectivity and application delivery to globally distributed enterprises. Aryaka is headquartered in San Mateo, California with additional offices located in London, United Kingd ...
* Azure CDN * CacheFly * CDNetworks * CenterServ * ChinaCache *
Cloudflare Cloudflare, Inc. is an American web infrastructure and website security company that provides content delivery network A content delivery network, or content distribution network (CDN), is a geographically distributed network of proxy servers ...
* Cotendo * EdgeCast Networks * Fastly * Google Cloud CDN * HP Cloud Services *
Incapsula Imperva Incapsula is an American Cloud computing, cloud-based application delivery platform. It uses a global content delivery network to provide web application security, Denial-of-service attack#Distributed DoS, DDoS DDoS mitigation, mitigatio ...
* Instart *
Internap Internap Corporation is a company that describes itself as a "global provider of performance-driven, full-spectrum data center and cloud solutions". The company is headquartered in Reston, Virginia, United States, with company-controlled data cent ...
* *
Lumen Technologies Lumen Technologies, Inc. (formerly CenturyLink) is an American telecommunications company A telephone company, also known as a telco, telephone service provider, or telecommunications operator, is a kind of communications service provider ...
, formerly
Level 3 Communications Level 3 Communications was an American multinational Multinational may refer to: * Multinational corporation, a corporate organization operating in multiple countries * Multinational force, a military body from multiple countries * Multinationa ...
*
Limelight Networks Limelight Networks is an American company that provides a content delivery network (CDN) service, used for delivery of digital media content and software. As of February 2020, the company's network has more than 130 points-of-presence and delive ...
*
MetaCDN MetaCDN is a Cloud computing, cloud-based content delivery network company that also offers video transcoding, streaming video and web accelerator services. Founded in 2011 from research out of the University of Melbourne, MetaCDN is backed by Au ...
* NACEVI *
OnApp OnApp is a London, UK London is the capital and largest city of England England is a Countries of the United Kingdom, country that is part of the United Kingdom. It shares land borders with Wales to its west and Scotland to its nort ...
*
Godaddy GoDaddy Inc. is an American publicly traded Internet domain registrar and web hosting A web hosting service is a type of Internet hosting service The Internet ( or internet) is the global system of interconnected computer netw ...
* OVH * Rackspace Cloud Files * Speedera Networks * StackPath * StreamZilla * Wangsu Science & Technology * Yottaa


Telco CDNs

* AT&T Inc. *
Bharti Airtel Bharti Airtel Limited, also known as Airtel, is an Indian multinational telecommunications Telecommunication is the transmission of information Information can be thought of as the resolution of uncertainty; it answers the question ...
*
Bell Canada Bell Canada (commonly referred to as Bell) is a Canadian Canadians (french: Canadiens) are people identified with the country of Canada. This connection may be residential, legal, historical or cultural. For most Canadians, many (or all) ...
*
BT Group BT Group plc (trade name, trading as BT and formerly British Telecom) is a British Multinational corporation, multinational telecommunications holding company headquartered in London, England. It has operations in around 180 countries and is th ...
*
China Telecom China Telecom Corp., Ltd. is a Chinese telecommunications company. It is one of the red chip listed companies of State-owned enterprise, state-owned China Telecommunications Corporation. Its H shares have been traded on the Stock Exchange of Ho ...
*
Chunghwa Telecom Chunghwa Telecom Company, Ltd. () (, ) is the largest telecommunication Telecommunication is the transmission of information Information can be thought of as the resolution of uncertainty; it answers the question of "What an entity ...
*
Deutsche Telekom Deutsche Telekom AG (; short form often just Telekom or DT; stylised as ·T···) is a German telecommunications company headquartered in Bonn and by revenue the largest telecommunications provider in Europe. Deutsche Telekom was formed in 1995, ...

Deutsche Telekom
* KT *
KPN KPN (in full Koninklijke KPN N.V., also Royal KPN N.V.) is a Dutch landline and mobile telecommunications company. KPN originated from a government-run postal, telegraph and telephone service and is based in Rotterdam Rotterdam (, , ) is ...

KPN
*
Lumen Technologies Lumen Technologies, Inc. (formerly CenturyLink) is an American telecommunications company A telephone company, also known as a telco, telephone service provider, or telecommunications operator, is a kind of communications service provider ...
, formerly CenturyLink *
Megafon MegaFon (russian: МегаФон), previously known as North-West GSM, is the second largest mobile phone operator
* NTT *
Pacnet Pacnet was a global telecommunications service provider between 2008 and 2015 before it was acquired by Telstra. It was formed from the operational merger of Asia Netcom and Pacific Internet on 8 January 2008. It was owned by a private investor gr ...
*
PCCW PCCW Limited (formerly known as Pacific Century CyberWorks Limited) is a Hong Kong Hong Kong (; , ), officially the Hong Kong Special Administrative Region of the People's Republic of China (HKSAR), is a city A city is a large human ...
* Qualitynet *
Singtel Singapore Telecommunications Limited, commonly known as Singtel and stylised as SingTel, is a Singaporean telecommunications Telecommunication is the transmission of information by various types of technologies over , radio, , or other s ...
*
SK Broadband SK Broadband, Inc. , formerly known as Hanaro Telecom, is a Seoul Seoul (, like ''soul''; ko, 서울 ; ), officially the Seoul Special City, is the capital Capital most commonly refers to: * Capital letter Letter case (or just ...
*
Spark New Zealand Spark New Zealand Limited is a New Zealand telecommunications company providing fixed-line telephone services, a mobile phone A mobile phone, cellular phone, cell phone, cellphone, handphone, or hand phone, sometimes shortened to simply ...
*
Tata Communications Tata Communications Limited is an Indian telecommunications company. The company is part of the Tata Group Tata Group () is an Indian multinational conglomerate headquartered in Mumbai Mumbai (, ; also known as Bombay , List of re ...
*
Telecom Argentina Telecom Argentina S.A. is the major local telephone company for the northern part of Argentina Argentina (), officially the Argentine Republic ( es, link=no, República Argentina), is a country located mostly in the southern half of South Amer ...
* Telefonica *
Telenor Telenor ASA (Oslo Stock Exchange, OSE: TEL, or ) is a Norway, Norwegian majority State-owned enterprise, state-owned multinational corporation, multinational telecommunications company headquartered at Fornebu in Bærum, close to Oslo. It is one ...

Telenor
*
TeliaSonera Telia Company AB is a Swedish multinational telecommunications company and mobile network operator present in Sweden, Finland, Norway, Denmark, Lithuania, Latvia and Estonia. Telia also owns TV4 Media which includes TV4 in Sweden and MTV in Fin ...
* Telin *
Telstra Telstra Corporation Limited is an Australian telecommunications Telecommunication is the transmission of information by various types of technologies over , radio, , or other systems. It has its origin in the desire of humans for commun ...

Telstra
*
Telus Telus Communications Inc. (TCI) is the wholly owned principal subsidiary of Telus Corporation, a Canadian Canadians (french: Canadiens) are people identified with the country of Canada Canada is a country in the northern part ...
* TIM * Turk Telekom *
Verizon Verizon Communications Inc., commonly known as Verizon, is an American multinational telecommunications Telecommunication is the transmission of information by various types of technologies over wire, radio, Optical system, optical, or ot ...


Commercial CDNs using P2P for delivery

* BitTorrent, Inc. *
Internap Internap Corporation is a company that describes itself as a "global provider of performance-driven, full-spectrum data center and cloud solutions". The company is headquartered in Reston, Virginia, United States, with company-controlled data cent ...
* Pando Networks *
Rawflow{{short description, Streaming technology company RawFlow was a provider of live Peer-to-peer, p2p Streaming media, streaming technology that enables internet broadcasting of audio and video. The company's technology is similar to Abacast and Octosha ...


Multi CDN

*
MetaCDN MetaCDN is a Cloud computing, cloud-based content delivery network company that also offers video transcoding, streaming video and web accelerator services. Founded in 2011 from research out of the University of Melbourne, MetaCDN is backed by Au ...
* Warpcache


In-house CDN

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Netflix Netflix, Inc. is an American subscription The subscription business model is a business model in which a customer In sales Sales are activities related to selling or the number of goods sold in a given targeted time period. Th ...

Netflix
How Netflix works: the (hugely simplified) complex stuff that happens every time you hit Play
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See also

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Application software Application software (app for short) is computing software designed to carry out a specific task other than one relating to the operation of the computer itself, typically to be used by end-users. Examples of an application Application may refer ...
* Bel Air Circuit *
Comparison of streaming media systems This is a comparison of streaming media Streaming media is multimedia Multimedia is a form of communication that combines different content forms such as text, audio, images, animations, or video into a single presentation, in contrast t ...
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Comparison of video services The following tables compare general and technical information for a number of current, notable video hosting services. Please see the individual products' articles for further information. General information Basic general information about the ...
* Content delivery network interconnection *
Content delivery platform A content delivery platform (CDP) is a software as a service Software as a service (SaaS ) is a software licensing and software delivery, delivery model in which software is licensed on a subscription basis and is centrally Internet hosting servic ...
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Data center A data center (American English American English (AmE, AE, AmEng, USEng, en-US), sometimes called United States English or U.S. English, is the set of varieties of the English language native to the United States. Currently, American Eng ...
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Digital television Digital television (DTV) is the transmission of television audiovisual Audiovisual (AV) is electronic media 200px, Graphical representations of electrical audio data. Electronic media uses either analog (red) or digital (blue) signal pr ...
* Dynamic site acceleration *
Edge computing Edge computing is a distributed computing Distributed computing is a field of computer science Computer science deals with the theoretical foundations of information, algorithms and the architectures of its computation as well as practical ...
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Internet radio Internet radio (also web radio, net radio, streaming radio, e-radio, IP radio, online radio) is a digital audio Digital audio is a representation of sound recorded in, or converted into, Digital signal (signal processing), digital form. In ...
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Internet television Streaming television is the digital distribution Digital distribution (also referred to as content delivery, online distribution, or electronic software distribution (ESD), among others) is the delivery or distribution of digital media Dig ...
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IPTV Internet Protocol television (IPTV) is the delivery of television Television, sometimes shortened to TV or telly, is a telecommunication Media (communication), medium used for transmitting moving images in grayscale, black-and-white ...

IPTV
* List of music streaming services * List of streaming media systems * Multicast * NetMind * Open Music Model * Over-the-top content * P2PTV * Protection of Broadcasts and Broadcasting Organizations Treaty * Push technology * Software as a service * Streaming media * Webcast * Web syndication * Web television


References


Further reading

* * * * * {{Video digital distribution platforms Content delivery networks, Applications of distributed computing Cloud storage Computer networking Digital television Distributed algorithms Distributed data storage Distributed data storage systems File sharing File sharing networks Film and video technology Internet broadcasting Internet radio Streaming television Multimedia Online content distribution Peer-to-peer computing Peercasting Streaming Streaming media systems Video hosting Video on demand