One of the recommendations in SharePoint 2013 is the usage of Host Named Site Collections (HNSCs) over using multiple web applications when you want to use vanity urls for specific SharePoint sites. Host-named site collections each have a unique DNS host name and therefore its own top-level URL. SharePoint 2013 allows you to add multiple URLs by using the Set-SPSiteURL Powershell command. An interesting quote around this is found in a new article Host-named site collection architecture and deployment (SharePoint 2013) :
Because the Office 365 environment uses host-named site collections, new features are optimized for these site collections and they are expected to be more reliable. Learn how to plan for and implement host-named site collections, design URLs, and manage URLs.
The same information is found in SharePoint 2013 design samples – corporate portals and extranet sites :
The recommended configuration for deploying sites is using host-named site collections with all sites located within a single web application. This configuration is recommended to deploy sites because it is the same architecture that the Office 365 environment uses. Consequently this is the most heavily tested configuration. New features, including the App model and Request Management, are optimized for this configuration, and it is the most reliable configuration going forward.
Some of the reasons why host-named site collections are also considered to be the better solution because: