URL redirection 328
Redirect loops
It is quite possible that one redirect leads to another redirect. For example, the URL http:/ / http://www. wikipedia. com/
wiki/ URL_redirection (note the differences in the domain name) is first redirected to http:/ / http://www. wikipedia. org/
wiki/ URL_redirection and again redirected to the correct URL: http:/ / en. wikipedia. org/ wiki/ URL_redirection.
This is appropriate: the first redirection corrects the wrong domain name, the second redirection selects the correct
language section, and finally, the browser displays the correct page.
Sometimes, however, a mistake can cause the redirection to point back to the first page, leading to an infinite loop of
redirects. Browsers usually break that loop after a few steps and display an error message instead.
The HTTP standard [11] states:
A client SHOULD detect infinite redirection loops, since such loops generate network traffic for each
redirection.
Previous versions of this specification recommended a maximum of five redirections; some clients may exist
that implement such a fixed limitation.Services
There exist services that can perform URL redirection on demand, with no need for technical work or access to the
webserver your site is hosted on.URL redirection services
A redirect service is an information management system, which provides an internet link that redirects users to the
desired content. The typical benefit to the user is the use of a memorable domain name, and a reduction in the length
of the URL or web address. A redirecting link can also be used as a permanent address for content that frequently
changes hosts, similarly to the Domain Name System.
Hyperlinks involving URL redirection services are frequently used in spam messages directed at blogs and wikis.
Thus, one way to reduce spam is to reject all edits and comments containing hyperlinks to known URL redirection
services; however, this will also remove legitimate edits and comments and may not be an effective method to
reduce spam.
Recently, URL redirection services have taken to using AJAX as an efficient, user friendly method for creating
shortened URLs.
A major drawback of some URL redirection services is the use of delay pages, or frame based advertising, to
generate revenue.History
The first redirect services took advantage of top-level domains (TLD) such as ".to" (Tonga), ".at" (Austria) and ".is"
(Iceland). Their goal was to make memorable URLs. The first mainstream redirect service was V3.com that boasted
4 million users at its peak in 2000. V3.com success was attributed to having a wide variety of short memorable
domains including "r.im", "go.to", "i.am", "come.to" and "start.at". V3.com was acquired by FortuneCity.com, a
large free web hosting company, in early 1999. In 2001 emerged .tk (Tokelau) as a TLD used for memorable
names.[8] As the sales price of top level domains started falling from $70.00 per year to less than $10.00, the demand
for memorable redirection services eroded.
With the launch of TinyURL in 2002 a new kind of redirecting service was born, namely URL shortening. Their goal
was to make long URLs short, to be able to post them on internet forums. Since 2006, with the 140 character limit on
the extremely popular Twitter service, these short URL services have seen a resurgence.