How does a screened host setup differ from a dual-homed host configuration?  Why might you choose this configuration?

What will be an ideal response?

A screened host setup is similar to a dual-homed host, but the main difference is that a router
is often added between the host and the Internet to carry out IP packet filtering.  A screened host is essentially a combination of a dual-homed host and screening router configuration; the two are blended for an added layer of functionality, security, and performance. You might choose this setup for perimeter security on a corporate network.  A common enhancement is to have a screened host function as an application gateway or proxy server. The only network services allowed to pass through the proxy server are those for which proxy applications are already available.