404ing invalid get/post data

[ShadowFusion]

Hi, I was wondering whether sites should silently accept invalid get/post data or not?

e.g. if someone tries to add a ?id=20 to a static page. Should you tell them the request is wrong by 404ing or just ignore it?

Same question with post data, e.g. an additional invalid field. Should you reject the entire request or just ignore it?

Ignoring it may result in the client thinking their data was processed successfully which isn't good.

What do other people think?

Edit: Something to note. Google returns a 404 for invalid get data...

[SSJ]

I don't think it will affect your site's performance if you have static site and they are adding any no of parameters. But if you have dynamic site then you need to take care of it.

I am always checking it via dynamic PHP or ASP code and giving an error if any one tried any hacks.

You can set it via IIS also where you need to set the default Error Page