Question

A layer -4 firewall (a device that can look at all protocol headers up to the transport layer) CANNOT

• A. block all ICMP traffic
• B. stop incoming traffic from a specific IP address but allow outgoing traffic to the same IP address
• C. block entire HTTP traffic during 9:00 pm and 5:00 am
• D. block TCP traffic from a specific user on a multi-user system during 9:00 pm and 5:00 am

Answer 1

The correct option is C block entire HTTP traffic during 9:00 pm and 5:00 am

To block TCP traffic from specific user, requires information of specific user which is done by application layer. To block HTTP data, layer-4, i.e., transport layer can be used because it can block port used by HTTP.