Assignment 2

URL: Uniform Resource Locator
In the world of computer science, the URL specifies where a certain identified resource is located and the means by which you may access it. Every URL consists of some of the following: the scheme name, commonly called protocol; followed by a colon, then, depending on the scheme, a hostname otherwise known as an IP address; a port number, which is the path of the resource to be retrieved or the program to be run, then, for certain programs, a query string, with HTML documents, an anchor which is optional for where the page should start to be displayed. The combined URL resembles one such as this: http://en.wikipedia.org/wiki/Uniform_Resource_Locator. Therefore, a URL is a uniform resource identifier that does, among identifying the location of a resource, provides a way to locate the resource by describing its primary access mechanism.

TCP/IP: Transmission Control Protocol and Internet Protocol
The Internet Protocol Suite popularly known as TCP/IP is the set of communications protocols used for the Internet and other similar networks. It is named from two of the most important protocols in it: the Transmission Control Protocol (TCP) and the Internet Protocol (IP), which were the first two networking protocols defined in this standard. The Internet Protocol Suite, like many protocol suites, may be viewed as a set of layers. Each layer solves a set of problems involving the transmission of data, and provides a well-defined service to the superior layer protocols based on using services from some lower layers. Superior layers are logically closer to the user and deal with more abstract data, relying on lower layer protocols to translate data into forms that can eventually be physically transmitted. The four layers, from lower to superior are: link layer, internet layer, transport layer and application layer.

HTTP: Hypertext Transfer Protocol
HTTP is the underlying protocol used by the World Wide Web. It defines how messages are formatted and transmitted, and what actions Web servers and browsers should take in response to various commands. HTTP is a formal communication method that transmits requests and data between user agents or web browsers and Web servers. When you enter a URL in your browser, this actually sends an HTTP command to the Web server directing it to fetch and transmit the requested Web page. Hypertext Transfer Protocol is an application-level protocol for distributed, collaborative, hypermedia information systems. Its use for retrieving inter-linked resources, called hypertext documents, led to the establishment of the World Wide Web. It is called a stateless protocol because each command is executed independently, without any knowledge of the commands that came before it.

Web server
A web server is a computer program that delivers content, such as a web page, using the Hypertext Transfer Protocol. This service is referred to as web hosting. The person who is in charge of the server is the web host. The web host may rent space on the web server to people or businesses for the purpose of them setting up web sites. The term web server can also refer to the computer or virtual machine running the program. Its primary function is the delivery of HTML documents and other relevant information that may be included in a document, such as an image. While this is so, it has the capability to receive information from its clients. This is why we can upload files on the internet.

Protocol
In general, a protocol is a rule determining the format and transmission of data. In computing, a protocol is a set of rules which is used by computers to communicate with each other across a network. A protocol is a standard that controls or enables the connection, communication, and data transfer between computing endpoints. In its simplest form, a protocol can be defined as the rules governing the syntax, semantics, and synchronization of communication. Protocols may be implemented by hardware, software, or a combination of both. At the lowest level, a protocol defines the behavior of a hardware connection. It defines certain actions such as: how to detect loss of connection and the actions as a result, or what to do with corrupted files, among others.

DNS: Domain Name Service
The Domain Name System (DNS) is a naming system based on a hierarchy for computers, services, or any resource connected to the Internet or a private network. It associates a variety of information with domain names assigned to each of the participants. Most importantly, it translates domain names meaningful to humans into the numerical identifiers associated with networking equipment, binary, for the purpose of locating and addressing these devices worldwide. It is the phonebook of the internet, converting human-friendly computer hostnames into IP addresses. The Domain Name System makes it possible to assign domain names to groups of Internet users in a meaningful way, independent of each user's physical location. Because of this, World Wide Web 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 so people take advantage of this when they recite meaningful URLs and e-mail addresses without having to know how the machine will actually locate them. The Domain Name System distributes the responsibility of assigning domain names and mapping those names to IP addresses by designating governing name servers for each domain. These 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, fault tolerant, and helped avoid the need for a single central register to be continually consulted and updated. The DNS also stores other types of information such as the list of mail servers that accept email for a given Internet domain.