ISP redirects?

If I enter a URL for a nonexistent site, how is it possible...

[Josefu]

For my ISP to trap that error and redirect me to a site of their choice?

I've never been more annoyed in my life. For a client I was doing a search for available domain names, and since yesterday, every time I enter a non-existant URL I am redirected to a "navigation help" page bearing my ISP's logo - and from there I am redirected to a page advertising travel or something similar.

I of course would like to ask how to stop this, but would like more to know how they manage to do it. Until my ISP started its antics I would often be re-directed to some sort of scraper directory when I did the same thing, and I imagine they use the same technique.

How do they do this? The header?

Thanks for any help.

[physics]

I'm not sure how they're doing this but ...
VeriSign was doing this back in 2003 news story [news.com.com]
But also I think spyware can do this ... have you checked for spyware?

[jdMorgan]

Since you are probably using the DNS servers offered by your ISP, it's a simple matter for them to pass their own IP address to your browser when it requests a DNS lookup on an unregistered domain. The simple cure is to change your network configuration to use different DNS servers. You can search to find "independent" DNS providers.

Jim

[Josefu]

...as always, thanks Jim. Bypassing my ISP's providers is a thing a bit new to me though. I'll look in to it - but thanks for telling me where to look : )