Can these query strings cause loss of traffic?

[fsmobilez]

I have noticed this that there was a page indexed in google like this

www.example.com/?www.example.net=

means after / there is a link of other site i removed that using wmt

but today i loss ranking again i checked and another site link was there in google

www.example.com/?www.example.net=

i dont know how and why google is indexing urls like this and what should i do to permanently stop google doing this

it is shown when i searched for

site:www.example.com linkexchange

and yes can it be main reason of losing traffic

[tedster]

How does your server respond when asked for that url?

[Marcia]

You can see what it returns by adding /?google.com at the end of any domain; it returns a 200 page returned. That makes it dup content with a different URL, doesn't it?

It's been a very common, deliberate tactic for a long time, used by log spammers wanting attention and "invited" visits.

[fsmobilez]

>>>How does your server respond when asked for that url?

They shows the same main index page of the site.

>>>You can see what it returns by adding /?google.com at the end of any domain; it returns a 200 page returned. That makes it dup content with a different URL, doesn't it?

Yes it do how to get rid of it.?

[Marcia]

You can get rid of it in .htaccess but it's the query string part that takes special consideration. There are threads about this in the Apache forum.