Multi-Tier Architecture
Multi-Tier architectures provide additional layers of security. In order to retrieve sensitive data, an attacker would have to compromise each tier individually before accessing the database layer.
Utilizing distinct layers separated into Virtual Local Area Networks (VLANs) has great security advantages. Outside network traffic is filtered at the firewall to only allow necessary services and their associated ports (usually HTTP and HTTPS on TCP port 80 and 443 respectively) to pass to the web layer VLAN. The firewall then restricts web server communication to the application layer VLAN via specific ports and protocols. Similarly, the application layer may only communicate with the database layer VLAN via its associated ruleset (i.e. ODBC). Outside network traffic will not pass directly to either the application layer VLAN or the database layer VLAN.
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