unusual phenomenon

Hi,

Sometimes I encountered this phenomenon when browsing through the net:

In sample1.htm there is a link <a href='http://www.xxx.com/xxx/abc.asp?id_1=123&id_2=456'> . If I click this link from the page, I can get the query result I want. But if I copy this link and paste it back to the browser's address bar and press enter, it will bring me back to the homepage. How can this happen?

Thanks!

It's all about referrals. When you click on the link, the browser adds another header, like:

Code:

---

HTTP-Referrer: http://www.xxx.com/xxx/sample1.htm

---

The ASP checks for this, so that it knows what page it came from. If it's not there, it redirects you to the homepage. It's basically a security mechanism to stop people from hijacking your scripts.

Thanks!
where can I find some more information about referral page?
I'm very intested in this security measure. :>

is it possible that this phenomenon is done by setting cookies?