Hi Jon

There is a change you can make to the web.config to force all requests to a single portal alias.  This is assuming the 'redirectToSubdomain' isn't enough for you (ie, you have www.domain1.com and www.domain2.com, and want all to go to www.domain1.com)

The change you need to make is to add this into the dnnFriendlyUrl section in the web.config:

usePortalAlias="0,www.domain.com"

Where 0 = the portal Id you want to redirect for, and www.domain.com is the portal alias you would like all requests redirected to.

You can check this with Fiddler, or a similar http traffic monitoring tool - when you request on the incorrect alias, you should see a Response Header added:

x-redirect-reason: wrong portal alias

Hope this helps?

-Bruce