Looking for 404's in my log files.

Why would .gif, .css, .rdf trigger a 404?

[Broadway]

I've been looking through my log files to see when my custom 404 page has been triggered.

I've noticed that I see it triggered with non-existant files with the extensions .css, .gif, .rdf

I've tested the .css and .gif file types in some test html pages. If you call a non-existant file from within html the page simple doesn't show the graphic or get stylized correctly, no 404 is triggered.

If you type in the browser address bar an incorrect file name with one of these extensions you do get transferred to the 404 page.

So who, how, why, what person, what machine, would be calling for these files directly as opposed these files getting called by a browser due to the directives within a html file?

There can't be that many overly curious or thieving people interested in my site. It has to be some machine doing some type of "normal" activity.

[jdMorgan]

The 404 response is sent by the server for any non-existent URL request. However, the browser cannot display a 404 page in place of an image -- The <img src=> -handling code cannot render an (another) HTML error page within the current HTML page. For one thing, the Content-type is wrong, the expected content-type being (for example) image/gif and a 404 page being text/html.

Use a server headers checker such as Live HTTP Headers to confirm this if you like. The 404 response is always sent.

So you're looking at the wrong end of things and over-complicating. The question is simply, "Where are these bad links coming from and/or why?"

Jim