Internet Addressing

In order to route a message across the Internet, each connected device must have a unique address that distinguishes it from all the other nodes.
URL (Uniform Resource Locator)
URL is a standard for specifying the location of an object on the Internet. Below are some example URLs:

  • http://undcemcs02.und.edu/~user.id/
  • https://www.google.com/search?hl=en&q=ip&btnG=Search
  • ftp://wuarchive.wustl.edu/mirrors/gifkit.zip
  • mailto:dbh@doc.ic.ac.uk
  • telnet://dra.com

The part before the first colon specifies the access scheme or protocol. For HTTP, two slashes after the colon introduce a hostname. The next part is a pathname which is usually related to the pathname of a file on the server. The last (optional) part of the URL may be a query string preceded by ‘?’.
URI (Universal Resource Identifier)
URI is a formatted string that serves as an identifier for a resource on the Internet. URIs that specify a common Internet protocol such as HTTP or FTP are also called URLs. URI is a superset of URL. For the sake of simplicity, you may treat URI and URL the same at this moment.
ICANN (Internet Corporation for Assigned Names and Numbers)
The non-profit corporation that was formed to assume responsibility for IP address allocation, protocol parameter assignment, domain name system management, and root server system management functions
ISP (Internet Service Provider)
A company that provides an Internet connection such as Midcontinent Communications



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