Sharepoint 2010 Host-named site collection

In SharePoint environment, site collection can be created with following naming pattern:

http://company.com/sites/app1
http://company.com/sites/app2

However, if there is a requirement to create applications with its unique DNS names, e.g app1.company.com, app2.company.com, while still maintain scalability of your SP Farm?

One way to do this is to create SP Web Application for each application, however this way does not scale.
Create hundred of Web Application in a WFE does not look good to me. Some information regarding SharePoint limits and boundaries here.

Another way to do this is use host-named site collection. With one site collection per application, this scales as much as site collection does.
SharePoint Server 2010 provides two significant improvements to host-named site collections: the ability to use managed paths with host-named site collections, and the ability to use off-box SSL termination with host-named site collections.

Create a host-named site collection
You must use Windows PowerShell to create a host-named site collection. You cannot use the SharePoint Server 2010 Central Administration Web application to create a host-named site collection, but you can use Central Administration to manage the site collection after you have created it.

New-SPSite http://host.header.site.url -OwnerAlias DOMAIN\username -HostHeaderWebApplication http://servername

Tai -

Reference: Plan for host-named site collections (SharePoint Server 2010)