What is the most common firewall topology?

The most common firewall topology is the "dual-homed" configuration, where a firewall is placed between an internal network and an external network, such as the internet. This setup typically involves two network interfaces: one connected to the internal network and the other to the external network. This configuration allows for controlled access and monitoring of traffic between the two networks, enhancing security while enabling communication. Additionally, variations like "screened subnet" or DMZ (Demilitarized Zone) topologies are also frequently used to provide added layers of security.