The Domain Name System (DNS) is a hierarchical naming system built on a distributed database for computers, services, or any resource connected to the Internet or a private network. Most importantly, it translates domain names meaningful to humans into the numerical identifiers associated with networking equipment for the purpose of locating and addressing these devices worldwide. An often-used analogy to explain the Domain Name System is that it serves as the “phone book” for the Internet by translating human-friendly computer hostnames into IP addresses.
The Domain Name System makes it possible to assign domain names to groups of Internet resources and users in a meaningful way, independent of each entity’s physical location. Because of this, World Wide Web (WWW) hyperlinks and Internet contact information can remain consistent and constant even if the current Internet routing arrangements change or the participant uses a mobile device. Internet domain names are easier to remember than IP addresses.
The Domain Name System distributes the responsibility of assigning domain names and mapping those names to IP addresses by designating authoritative name servers for each domain. Authoritative name servers are assigned to be responsible for their particular domains, and in turn can assign other authoritative name servers for their sub-domains. This mechanism has made the DNS distributed and fault tolerant and has helped avoid the need for a single central register to be continually consulted and updated. In general, the Domain Name System also stores other types of information, such as the list of mail servers that accept email for a given Internet domain. By providing a worldwide, distributed keyword-based redirection service, the Domain Name System is an essential component of the functionality of the Internet.
he domain name space consists of a tree of domain names. Each node or leaf in the tree has zero or more resource records, which hold information associated with the domain name. The tree sub-divides into zones beginning at the root zone. A DNS zone may consist of only one domain like a site I just worked on for the HCG diet it only had 1 domain, or may consist of many domains and sub-domains, depending on the administrative authority delegated to the manager. Administrative responsibility over any zone may be divided by creating additional zones. Authority is said to be delegated for a portion of the old space, usually in form of sub-domains, to another name server and administrative entity. The old zone ceases to be authoritative for the new zone.
An authoritative name server is a name server that gives answers that have been configured by an original source, for example, the domain administrator or by dynamic DNS methods, in contrast to answers that were obtained via a regular DNS query to another name server. An authoritative-only name server only returns answers to queries about domain names that have been specifically configured by the administrator. An authoritative name server can either be a master server or a slave server. A master server is a server that stores the original (master) copies of all zone records. A slave server uses an automatic updating mechanism of the DNS protocol in communication with its master to maintain an identical copy of the master records.
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Web development is a broad term for the work involved in developing a web site for the Internet (World Wide Web) or an intranet (a private network). This can include web design, web content development, client liaison, client-side/server-side scripting, web server and network security configuration, and e-commerce development. However, among web professionals, “web development” usually refers to the main non-design aspects of building web sites: writing markup and coding. Web development can range from developing the simplest static single page of plain text to the most complex web-based internet applications, electronic businesses, or social network services. For larger organizations and businesses, web development teams can consist of hundreds of people (web developers). Smaller organizations may only require a single permanent or contracting webmaster, or secondary assignment to related job positions such as a graphic designer and/or information systems technician. Web development may be a collaborative effort between departments rather than the domain of a designated department.
Since the mid-1990s, web development has been one of the fastest growing industries in the world. In 1995 there were fewer than 1,000 web development companies in the United States, but by 2005 there were over 30,000 such companies in the U.S. alone. The growth of this industry is being pushed by large businesses wishing to sell products and services to their customers and to automate business workflow. In addition, cost of Web site development and hosting has dropped dramatically during this time. Instead of costing ten thousands of dollars, as was the case for early websites, one can now develop a simple web site for free using one of the many free website builders such as Google Sites etc, depending on the complexity and amount of content. Smaller Web site development companies are now able to make web design accessible to both smaller companies and individuals further fueling the growth of the web development industry. As far as web development tools and platforms are concerned, there are many systems available to the public free of charge to aid in development.
A popular example is the LAMP (Linux, Apache, MySQL, PHP) stack, which is usually distributed free of charge. This fact alone has manifested into many people around the globe setting up new Web sites daily and thus contributing to increase in web development popularity. Another contributing factor has been the rise of easy to use WYSIWYG web development software, most prominently Adobe Dreamweaver, Netbeans, WebDev, or Microsoft Expression Studio, Adobe Flex. Using such software, virtually anyone can develop a Web page in a matter of minutes. Knowledge of HyperText Markup Language (HTML) or other programming languages is not required, but recommended for professional results.
The next generation of web development tools uses the strong growth in LAMP, Java Platform, Enterprise Edition technologies and Microsoft .NET technologies to provide the Web as a way to run applications online. Web developers now help to deliver applications as Web services which were traditionally only available as applications on a desk based computer. Instead of running executable code on a local computer, users are interacting with online applications to create new content.
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A web hosting service is a type of Internet hosting service that allows individuals and organizations to make their own website accessible via the World Wide Web. Web hosts are companies that provide space on a server they own or lease for use by their clients as well as providing Internet connectivity, typically in a data center. Web hosts can also provide data center space and connectivity to the Internet for servers they do not own to be located in their data center, called co-location or Housing as it is commonly called in Latin America or France.
The scope of web hosting services varies greatly. The most basic is web page and small-scale file hosting, where files can be uploaded via File Transfer Protocol (FTP) or a Web interface. The files are usually delivered to the Web “as is” or with little processing. Many Internet service providers (ISPs) offer this service free to their subscribers. People can also obtain Web page hosting from other, alternative service providers. Personal web site hosting is typically free, advertisement-sponsored, or inexpensive. Business web site hosting often has a higher expense. Single page hosting is generally sufficient only for personal web pages. A complex site calls for a more comprehensive package that provides database support and application development platforms. These facilities allow the customers to write or install scripts for applications like forums and content management. For e-commerce, SSL is also highly recommended.
The host may also provide an interface or control panel for managing the Web server and installing scripts as well as other modules and service applications like e-mail. Some hosts specialize in certain software or services (e.g. e-commerce). They are commonly used by larger companies to outsource network infrastructure to a hosting company.
Hosting uptime refers to the percentage of time the host is accessible via the internet. Many providers state that they aim for at least 99.9% uptime (roughly equivalent to 45 minutes of downtime a month, or less), but there may be server restarts and planned (or unplanned) maintenance in any hosting environment and this may or may not be considered part of the official uptime promise. Many providers tie uptime and accessibility into their own service level agreement (SLA). SLAs sometimes include refunds or reduced costs if performance goals are not met. Internet hosting services can run Web servers. Many large companies who are not internet service providers also need a computer permanently connected to the web so they can send email, files, etc. to other sites. They may also use the computer as a website host so they can provide details of their goods and services to anyone interested. Additionally these people may decide to place online orders.
Free web hosting service: offered by different companies with limited services, sometimes supported by advertisements, and often limited when compared to pay hosting. Shared web hosting service: one’s website is placed on the same server as many other sites, ranging from a few to hundreds or thousands. Typically, all domains may share a common pool of server resources. The features available with this type of service can be quite extensive. A shared website may be hosted with a reseller.
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Linux refers to the family of Unix-like computer operating systems using the Linux kernel. Linux can be installed on a wide variety of computer hardware, ranging from mobile phones, tablet computers, routers and video game consoles, to desktop computers, mainframes and supercomputers Linux is a leading server operating system, and runs the 10 fastest supercomputers in the world. The development of Linux is one of the most prominent examples of free and open source software collaboration; typically all the underlying source code can be used, freely modified, and redistributed, both commercially and non-commercially, by anyone under licenses such as the GNU General Public License. Typically Linux is packaged in a format known as a Linux distribution for desktop and server use. Some popular mainstream Linux distributions include Debian, Fedora and open SUSE. Linux distributions include the Linux kernel, supporting utilities and libraries and usually a large amount of application software to fulfill the distribution’s intended use.
A distribution oriented toward desktop use may include the X Window System, the GNOME and KDE Plasma desktop environments. Other distributions may include a less resource intensive desktop such as LXDE or Xfce for use on older or less-powerful computers. A distribution intended to run as a server may omit any graphical environment from the standard install and instead include other software such as the Apache HTTP Server and a SSH server like OpenSSH. Because Linux is freely redistributable, it is possible for anyone to create a distribution for any intended use. Commonly used applications with desktop Linux systems include the Mozilla Firefox web browser, the OpenOffice.org or LibreOffice office application suites, and the GIMP image editor.
A Linux-based system is a modular Unix-like operating system. It derives much of its basic design from principles established in UNIX during the 1970s and 1980s. Such a system uses a monolithic kernel, the Linux kernel, which handles process control, networking, and peripheral and file system access. Device drivers are either integrated directly with the kernel or added as modules loaded while the system is running.
Linux distributions support dozens of programming languages. The most common collection of utilities for building both Linux applications and operating system programs is found within the GNU tool chain, which includes the GNU Compiler Collection (GCC) and the GNU build system.[citation needed] Amongst others, GCC provides compilers for Ada, C, C++, Java, and Fortran. Proprietary compilers for Linux include the Intel C++ Compiler, Sun Studio, and IBM XL C/C++ Compiler. BASIC in the form of Visual Basic is supported in such forms as Gambas, FreeBASIC, and XBasic. Most distributions also include support for PHP, Perl, Ruby, Python and other dynamic languages. While not as common, Linux also supports C# (via Mono), Vala, and Scheme. A number of Java Virtual Machines and development kits run on Linux, including the original Sun Microsystems JVM, and IBM’s J2SE RE, as well as many open-source projects like Kaffe and JikesRVM. The two main frameworks for developing graphical applications are those of GNOME and KDE.
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Linux distributions have long been used as server operating systems, and have risen to prominence in that area; Net craft reported in September 2006 that eight of the ten most reliable internet hosting companies ran Linux distributions on their web servers. Since June 2008, Linux distributions represented five of the top ten, FreeBSD three of ten, and Microsoft two of ten; since February 2010, Linux distributions represented six of the top ten, FreeBSD two of ten, and Microsoft one of ten. Linux distributions are the cornerstone of the LAMP server-software combination (Linux, Apache, MySQL, and Perl/PHP/Python) which has achieved popularity among developers, and which is one of the more common platforms for website hosting. Linux distributions have become increasingly popular on mainframes in the last decade due to pricing, compared to other mainframe operating systems. In December 2009, computer giant IBM reported that it would predominantly market and sell mainframe-based Enterprise Linux Server.
Comparisons between the Microsoft Windows and Linux computer operating systems are a long-running discussion topic within the personal computer industry. Throughout the entire period of the Windows 9x systems through the introduction of Windows 7, Windows has retained an extremely large retail sales majority among operating systems for personal desktop use, while Linux has sustained its status as the most prominent Free Software and Open Source operating system. After their initial clash, both operating systems moved beyond the user base of the personal computer market and share a rivalry on a variety of other devices, with offerings for the server and embedded systems markets, and mobile internet access. Linux and Microsoft Windows differ in philosophy, cost, versatility and stability, with each seeking to improve in their perceived weaker areas. Comparisons of the two operating systems tend to reflect their origins, historic user bases and distribution models. Typical perceived weaknesses regularly cited have often included poor consumer familiarity with Linux, and Microsoft Windows’ susceptibility to viruses and malware.
The window manager is the Desktop Window Manager on Windows Vista, and a Stacking window manager built on top of GDI in older versions. The desktop environment may be modified by a variety of third party products such as Window Blinds; or completely replaced, for example by Black box for Windows, or Lite Step. With Windows Server 2008 and later server releases, there is also the option of running “Server Core” which lacks the standard window manager. The graphics drivers, subsystem, and core widgets are included with all installations, including those used as servers. The Command Prompt exists to provide direct communication between the user and the operating system.
A number of desktop environments are available, of which GNOME and KDE are the most widely used. By default, they use the Metacity and KWin window managers respectively, though these can be replaced by other window managers, such as Compiz Fusion. Other desktop environments and window managers include Xfce, LXDE, Enlightenment, Xmonad, Openbox, Fluxbox, etc. The X Window system runs in user-space and is optional. Multiple X Window system instances can run at once, and it is a fully networked protocol.
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