9.1. The Internet Domain Names and IP addresses

Aims Be able to compare terms such as Domain names and IP addresses URL,URI and URN Internet Registries and ISP

Domain Name Systems (DNS) The Domain Name System maps the domain names onto IP addresses as numbers are hard to memorise DNS is a distributed database of information is used to translate domain names (e.g. yale-wrexham.ac.uk) into the IP addresses ( )

Domain Name System Domain name: Identifies one or more IP addresses E.g. microsoft.com represents several IP addresses Fully Qualified Domain Name (FQDN) networkID and host ID (e.g ) (not a subfolder such as DNS Hierarchy Level1:.uk,.be,.de,.org,.net,.int,.edu,.gov. Level2:.co,.ac,.sch,.ltd

Domain Names The domain names specifies the name of the server or directory on which the Web resource is held. Domain names identify the type of organisation and often country in which the server is located Domain Name

Internet registrar and registries Internet registries store registered domain names They track association between Internet addresses such as and domain names Internet registrars – private companies responsible for registering Internet domains. e.g. InterNIC

Internet Service provider or Internet Access Providers (IAP) Some WANs act as service providers, and members of the public or businesses can join these networks in return for a monthly fee.

Uniform Resource Identifier This umbrella term is used for URLs and URNs A Uniform Resource Name (URN) is like a person's name, (what) A Uniform Resource Locator (URL) is like his or her street address. (where) A Uniform Resource Identifier (URI) is like a person’s name and address (what and where) The URN defines an item's identity, while the URL provides a method for finding it Examples are: ftp://ictweb/myfolder/myfile.txt Urn:isbn: X

Uniform Resource Locator (URL) How: Protocol used for connection to the server Where: Protocol used for connection to the server What: the path on the addressed server Other examples: ftp://host/file

Uniform Resource Name (URN) The term "Uniform Resource Name" (URN) refers to the subset of URI that identifies a resource by name in a given namespace but not define how the resource maybe obtained URNs are required to remain globally unique even when the resource ceases to exist or becomes unavailable. Example: Urn:isbn: X

World Wide Web A system of interlinked hypertext documents accessed via the internet which allows people to view information stored on participating computers. It consists of documents called pages that contain information on a particular topic, and links to other Web pages, which may be stored on other computers in different countries.

Intranet A private company wide network run along the lines of the World Wide Web and uses the same protocol as internet =>TCP/IP (not: LOCAL network) Advantages Sharing information and documents, databases and applications Specific information can be downloaded Only suitable material can be viewed