How do I handle invalid controllers

[eluser]Michael Wales[/eluser]
ew.. no no no - you should show a 404! The user is requesting a resource that doesn't exist, that is the definition of a 404.

By not throwing a 404 and instead redirecting to a controller you will get massive reductions in pagerank for duplicate content. Essentially, any of your competitors could create a page that links to 100 or so random, invalid controllers on your site, Google/Yahoo/MSN now see that 100 of your pages are exactly the same and they deduce that your site is nothing but spam.

You don't have to go with the default browser 404 design, you can design up the page however you want, add some helpful tips to the user (like links to what they may have been trying to access), etc. See this link for ideas: http://www.smashingmagazine.com/2009/01/...more-time/