How can I stop requests for favicon.ico without having a favicon.ico? It wastes resources serving a 404 and fills up logs with 404s. Right now I put in a dummy favicon.ico file but I would prefer a method of just telling browsers don't request favicon.
You haven't specified a web server however you appear to be involved in .net so I'm going to assume it's IIS
In which case you can filter your logs using something like this http://learn.iis.net/page.aspx/692/advanced-logging-for-iis---log-filtering/
You can do the same on most servers
You can't actually stop browsers requesting the image. However if you do have a favicon it can be cached by the browser which can reduce the number of requests coming in.
You can block favicon.ico requests from the browsers using the rewrite module for IIS. Basically you must install the module and activate it. Then you must create a rule in your web.config of your site or use the GUI on IIS Admin for creating it.
You can get more info there: http://www.iis.net/download/urlrewrite http://learn.iis.net/page.aspx/467/using-failed-request-tracing-to-trace-rewrite-rules
And for the rule, google for something like "rewrite favicon.ico" You will get plenty of hits from the Apache original version of the module, but there also are a bunch of people doing translations you can get on.
Hope it helps.