What Security issues would warrant this kind of URL linking

What are the reasons or security reasons why a URL would be linked this way

http://www.sampledemo.com/redirect?id=17&link=http://www.sampledemo.com/manual.php

instead of this way

http://www.开发者_JS百科sampledemo.com/manual.php

Thank you

Probably it isn't being used for security purposes. It might be used for site metrics and click tracking. It's hard to say what the id parameter is for. Could be something like an ID of the page being linked from.

If the URI was properly encoded (it isn't), then the only reasons I can think of are logging the hit and/or displaying a message to the user before they click to continue.

There are several reasons, but the most common one is that you want to track where you're being linked from. See the id argument? That very probably corresponds to the site.

There is no security reason. Usually something like this is used to track, where a visitor comes from. redirect will evaluate the id-parameter, that usually specifies one concrete (registered) referer and then redirect to the target page.