Web hosting service

From Wikipedia, the không tính phí encyclopedia

A web hosting service is a type of Internet hosting service that hosts websites for clients, i.e. it offers the facilities required for them to tướng create and maintain a site and makes it accessible on the World Wide Web. Companies providing trang web hosting services are sometimes called web hosts.

Typically, trang web hosting requires the following:

• one or more servers to tướng act as the host(s) for the sites; servers may be physical or virtual
• colocation for the server(s), providing physical space, electricity, and Internet connectivity;
• Domain Name System configuration to tướng define name(s) for the sites and point them to tướng the hosting server(s);
• a trang web server running on the host;
• for each site hosted on the server:
  • space on the server(s) to tướng hold the files making up the site
  • site-specific configuration
  • often, a database;
  • software and credentials allowing the client to tướng access these, enabling them to tướng create, configure, and modify the site;
  • email connectivity allowing the host and site to tướng send gmail to tướng the client.

History

Until 1991, the Internet was restricted to tướng use only "... for research and education in the sciences and engineering ..."^[1][2] and was used for gmail, telnet, FTP and USENET traffic—but only a tiny number of trang web pages. The World Wide Web protocols had only just been written^[3] and not until the over of 1993 would there be a graphical trang web browser for Mac or Windows computers.^[4] Even after there was some opening up of Internet access, the situation was confused^{[clarification needed]} until 1995.^[5]

To host a trang web on the mạng internet, an individual or company would need their own computer or server.^[2] As not all companies had the budget or expertise to tướng vì thế this, trang web hosting services began to tướng offer to tướng host users' websites on their own servers, without the client needing to tướng own the necessary infrastructure required to tướng operate the trang web. The owners of the websites, also called webmasters, would be able to tướng create a trang web that would be hosted on the trang web hosting service's server and published to tướng the trang web by the trang web hosting service.

As the number of users on the World Wide Web grew, the pressure for companies, both large and small, to tướng have an online presence grew. By 1995, companies such as GeoCities, Angelfire and Tripod were offering không tính phí hosting.^[6]

Classification

Static page hosting

The most basic is trang web page and small-scale tệp tin hosting, where files can be uploaded via File Transfer Protocol (FTP) or a trang web interface. The files are usually delivered to tướng the Web "as is" or with minimal processing. Many Internet service providers (ISPs) offer this service không tính phí to tướng subscribers. Individuals and organizations may also obtain trang web page hosting from alternative service providers.

Free trang web hosting service is offered by different companies with limited services, sometimes supported by advertisements,^{[needs update?]} and often limited when compared to tướng paid hosting.

Single page hosting is generally sufficient for personal trang web pages. Personal trang web hosting is typically không tính phí, advertisement-sponsored, or inexpensive. Business trang web hosting often has a higher expense depending upon the size and type of the site.

Peer-to-peer hosting

Larger hosting services

A complex site calls for a more comprehensive package that provides database tư vấn and application development platforms (e.g. ASP.NET, ColdFusion, Java EE, Perl/Plack, PHP or Ruby on Rails). These facilities allow customers to tướng write or install scripts for applications lượt thích forums and nội dung management. Web hosting packages often include a trang web nội dung management system, so sánh the end-user does not have to tướng worry about the more technical aspects. Secure Sockets Layer (SSL) is used for websites that wish to tướng encrypt the transmitted data.

Types of hosting

Internet hosting services can lập cập trang web servers. The scope of trang web hosting services varies greatly.

• Shared trang web hosting service – One's trang web is placed on the same server as many other sites, ranging from a few sites to tướng hundreds of websites. Typically, all domains may share a common pool of server resources, such as RAM and the CPU. The features available with this type of service can be quite basic and not flexible in terms of software and updates. Resellers often sell shared trang web hosting and trang web companies often have reseller accounts to tướng provide hosting for clients.
• Reseller trang web hosting – Allows clients to tướng become trang web hosts themselves. Resellers could function, for individual domains, under any combination of these listed types of hosting, depending on who they are affiliated with as a reseller. Resellers' accounts may vary tremendously in size: they may have their own virtual dedicated server to tướng a colocated server. Many resellers provide a nearly identical service to tướng their provider's shared hosting plan and provide the technical tư vấn themselves.
• Virtual Dedicated Server – Also known as a Virtual Private Server (VPS), divides server resources into virtual servers, where resources can be allocated in a way that does not directly reflect the underlying hardware. VPS will often be allocated resources based on a one server to tướng many VPSs relationship, however virtualisation may be done for a number of reasons, including the ability to tướng move a VPS container between servers. The users may have root access to tướng their own virtual space. Customers are sometimes responsible for patching and maintaining the server (unmanaged server) or the VPS provider may provide server admin tasks for the customer (managed server).
• Dedicated hosting service – The user gets their own trang web server and gains full control over it (user has root access for Linux/administrator access for Windows); however, the user typically does not own the server. One type of dedicated hosting is self-managed or unmanaged. This is usually the least expensive for dedicated plans. The user has full administrative access to tướng the server, which means the client is responsible for the security and maintenance of their own dedicated server.
• Managed hosting service – The user gets their own trang web server but is not allowed full control over it (user is denied root access for Linux/administrator access for Windows); however, they are allowed to tướng manage their data via FTP or other remote management tools. The user is disallowed full control so sánh that the provider can guarantee quality of service by not allowing the user to tướng modify the server or potentially create configuration problems. The user typically does not own the server. The server is leased to tướng the client.
• Colocation trang web hosting service – Similar to tướng the dedicated trang web hosting service, but the user owns the colo server; the hosting company provides physical space that the server takes up and takes care of the server. This is the most powerful and expensive type of trang web hosting service. In most cases, the colocation provider may provide little to tướng no tư vấn directly for their client's machine, providing only the electrical, Internet access, and storage facilities for the server. In most cases for colo, the client would have their own administrator visit the data center on site to tướng vì thế any hardware upgrades or changes. Formerly, many colocation providers would accept any system configuration for hosting, even ones housed in desktop-style minitower cases, but most hosts now require rack mount enclosures and standard system configurations.
• Cloud hosting – Hosting based on clustered load-balanced servers. A cloud hosted trang web may be more reliable than thở alternatives since other computers in the cloud can compensate when a single piece of hardware goes down. Also, local power disruptions or even natural disasters are less problematic for cloud hosted sites, as cloud hosting is decentralized. Cloud hosting also allows providers to tướng charge users only for resources consumed by the user, rather than thở a flat fee for the amount the user expects they will use, or a fixed cost upfront hardware investment. Alternatively, the lack of centralization may give users less control on where their data is located which could be a problem for users with data security or privacy concerns as per GDPR guidelines. Cloud hosting users can request additional resources on-demand such as only during periods of peak traffic, while offloading IT management to tướng the cloud hosting service.
• Clustered hosting – Having multiple servers hosting the same nội dung for better resource utilization. Clustered servers are a perfect solution for high-availability dedicated hosting, or creating a scalable trang web hosting solution. A cluster may separate trang web serving from database hosting capability. (Usually trang web hosts use clustered hosting for their shared hosting plans, as there are multiple benefits to tướng the mass managing of clients).^[8]
• Grid hosting – This khuông of distributed hosting is when a server cluster acts lượt thích a grid and is composed of multiple nodes.^{[citation needed]}
• Home server – A private server can be used to tướng host one or more websites from a usually consumer-grade broadband connection. These can be purpose-built machines or more commonly old PCs. Some ISPs block trang chủ servers by disallowing incoming requests to tướng TCP port 80 of the user's connection and by refusing to tướng provide static IP addresses. A common way to tướng attain a reliable DNS host name is by creating an trương mục with a dynamic DNS service. A dynamic DNS service will automatically change the IP address that a URL points to tướng when the IP address changes.^[9]

Some specific types of hosting provided by trang web host service providers:

• File hosting service: hosts files, not trang web pages
• Image hosting service
• Video hosting service
• Blog hosting service
• Paste bin
• Shopping cart software
• E-mail hosting service

Host management

The host may also provide an interface or control panel for managing the trang web server and installing scripts, as well as other modules and service applications lượt thích e-mail. A trang web server that does not use a control panel for managing the hosting trương mục, is often referred to tướng as a "headless" server. Some hosts specialize in certain software or services (e.g. e-commerce, blogs, etc.).

Reliability and uptime

The availability of a trang web is measured by the percentage of a year in which the trang web is publicly accessible and reachable via the Internet. This is different from measuring the uptime of a system. Uptime refers to tướng the system itself being online. Uptime does not take into trương mục being able to tướng reach it as in the sự kiện of a network outage.^{[citation needed]} A hosting provider's Service Level Agreement (SLA) may include a certain amount of scheduled downtime per year in order to tướng perform maintenance on the systems. This scheduled downtime is often excluded from the SLA timeframe, and needs to tướng be subtracted from the Total Time when availability is calculated. Depending on the wording of an SLA, if the availability of a system drops below that in the signed SLA, a hosting provider often will provide a partial refund for time lost. How downtime is determined changes from provider to tướng provider, therefore reading the SLA is imperative.^[10] Not all providers release uptime statistics.

Security

Because trang web hosting services host websites belonging to tướng their customers, online security is an important concern. When a customer agrees to tướng use a trang web hosting service, they are relinquishing control of the security of their site to tướng the company that is hosting the site. The level of security that a trang web hosting service offers is extremely important to tướng a prospective customer and can be a major factor when considering which provider a customer may choose.^[11]

Web hosting servers can be attacked by malicious users in different ways, including uploading malware or malicious code onto a hosted trang web. These attacks may be done for different reasons, including stealing credit thẻ data, launching a Distributed Denial of Service Attack (DDoS) or spamming.^[12]

See also

References