The correct answer is: O Domain Level Firewall
A Domain Level Firewall is not an available type of firewall. Let's take a look at the other options:
1. Stateful Inspection Firewall: This type of firewall monitors the state of network connections and keeps track of the context of each connection. It inspects incoming and outgoing packets, allowing or blocking them based on predetermined rules.
2. Application Level Gateway Firewall: Also known as a proxy firewall, it acts as an intermediary between internal and external networks. It provides a higher level of security by examining the content of the application layer protocols and making decisions based on that information.
3. Packet Filtering Firewall: This is a basic type of firewall that examines individual packets of data as they travel through a network. It filters packets based on preconfigured rules, such as source and destination IP addresses, ports, and protocols.
Remember, a Domain Level Firewall is not an actual type of firewall. The other three options mentioned above are all valid types of firewalls that are commonly used to protect networks from unauthorized access and threats.