Isolating SharePoint with Separate Web Applications

The problem of cross-site scripting attacks can be addressed through the creation of multiple host headers or virtual servers in SharePoint. Host headers allow for multiple domain names to correspond to different site collections in SharePoint. As a result, you can have a single SharePoint farm correspond to http://sharepoint.companyabc.com and http://sharepoint.cco.com and have them point to separate sets of data. This allows for an increased level of security between the sites because users cannot see the data from the other site collections. This, of course, reduces the amount of collaboration that can take place between the sites and is limited in scope.

By doing this, each site collection can be associated with a separate application pool. Each application pool is logically separate from the others and is theoretically not subject to failure if another one goes down or becomes corrupt. This also helps to further secure the SharePoint data because users are on separate physical processes from each other.