Some of the important components that the branch firewall uses for DIA are :

• Trusted DNS Server—Application detection in DIA feature relies on DNS snooping to resolve applications or a group of applications. To ensure that DNS requests are not resolved by rogue DNS servers and are indeed locked to the desired DNS servers, the management center allows you to configure a Trusted DNS server for Threat Defense.

• Interface Priority—Cisco Secure Firewall uses interface priority to determine the optimal internet path. Priority, lower the better, determines the preference of a particular ISP when sending the traffic out to the internet. The management center allows you to configure the interface priority for Threat Defense.

• Network Service—Object associated with a particular application that is used within policy based routing. This object is automatically created.

• Network Service Group (NSG)—Network Service Groups are a group of applications that the firewall uses to determine the path based on the configuration. Multiple network service objects can be part of a single NSG. The management center auto generates NSGs based on the extended access lists configured for policy based routing.