anosh needs to deploy a new web application that is publicly accessible from the internet. the web application depends on a database server to provide dynamic webpages, but he does not want to put the database server in a subnet that is publicly accessible for security reasons. which of the following devices would allow him to create a lightly protected subnet at the perimeter of the company's network that provides the ability to filer traffic moving between different networks, and is publicly accessible while still allowing the database server to remain in a private subnet?