We have a web application at x-x.com and a site collection at /sites/test (https://x-x.com/sites/test/) We have set up two vanity urls in our DNS so that in theory a user can type https://vanity1/sites/test or https://vanity2/sites/test. We initially thought that simply editing the bindings for the web application would allow us to us the vanity URLs...it is not working. Can someone step us through how to set it up so our vanity urls can be used to access our site collection?
Alternative access map is the feature desgined specifically for the purpose you describe.
The instructions I have linked to are for SharePoint v3 (WSS 3.0 and MOSS 2007), but remain the same for v4 (Foundation 2010, Server 2010). To my knowledge Microsoft has not provided updated instructions for the 2010 products and does reference this article in some of the 2010 product documentation.
AAM is not the most intuitive thing (well the concept is, but the implementation seems weird at times). SharePoint hard-codes the original URL into the content database and uses AAM to translate the vanity URLs to this. Do not edit the IIS bindings directly otherwise the translation will not happen correctly and you will get HTTP 404 errors seemingly at random.