From a security perspective, a very trivial element of a network is a firewall that can exist at multiple places within the network. For example a single system operating system contains its own copy of firewall which is a built in feature of today’s operating systems. Moreover advanced form of software firewall may be installed on the system.
Firewalls even exist at hardware and software level however we will stick to software base firewall for this network since software forms of the firewall are cost effective. Windows firewalls are available in two types
1) Host Based firewall
2) Network-Based firewall
Network-based firewall technology provides the protection to the network or servers in which the exchange of information travels between the user and servers. Windows firewall is used when any user or employee wants to connect to the network and shouldn’t have the rights to connect with the network. Firewall blocks that user and protects the network or server. Some firewalls provide sophisticated control like antivirus scanning, web content filtering and other application layer filtering which seems not to be the need of this network at the evolutionary stage. We have to keep in mind that since the primary question talks about handling of applications data we require application servers as well. To maintain 10 applications databases be running along with active directory, firewall and ISA server we will require a pool of 3-5 application servers be made part of the network that are secured for being in a separate LAN segment. We suggest that Microsoft Windows 2003 server be used for application servers. Each normal employee system of the network will be running Microsoft Windows 7 version for its elegant graphics, stable architecture and being light weight unless a different operating system is required (for example for a developer’s need)