Firewalled Subnets is a default address group and by default contains the address objects that are configured on the SonicWall firewall (Physical and VLAN sub-interfaces). This address group includes LAN, DMZ, WLAN, or any custom zones added with security type as trusted, wireless, or public. By default, the Firewalled Subnets address group doesn't contain any internally routed subnetworks via SonicWall firewall behind a Core Switch, Router, etc.,.
NOTE:The Default Address Groups entries cannot be modified or deleted. Therefore, the Edit and Delete icons are dimmed. This applies to Firewalled Subnets address group as it is part of Default Address Groups.
The below screenshot depicts both the default (LAN) and custom (HQ-LAN) zones used in the SonicWall interfaces.
The below screenshot depicts the Firewalled Subnets address group containing both the default and custom zones configured on the SonicWall interfaces.
This address group is useful while creating loopback NAT policies so that all the internal networks can access the hosted servers using the WAN public IP address.