Which of the following statements pertaining to firewalls NOT true?

A.
Firewalls create bottlenecks between the internal and external network.

B.
Firewalls allow for centralization of security services in machines optimized and dedicated to the task.

C.
Firewalls protect a network at all layers of the OSI models.

D.
Firewalls are used to create security checkpoints at the boundaries of private networks.

Explanation:
Packet filtering firewalls work at the network level of the OSI model.
If you filter specific ports, you can say you’re filtering at layer 4.
If your firewall inspects specific protocol states or data, you can say it operates at layer 7.
Firewalls do not work at layer 1, layer 2, or layer 3 of the OSI model.
Incorrect Answers:
A: Firewalls can create bottlenecks between the internal and external network.
B: Firewalls can be administered from a central location.
D: Firewall are most often placed at the boundaries of the private networks to implement a security checkpoint
to restrict access from the Internet.

Harris, Shon, All In One CISSP Exam Guide, 6th Edition, McGraw-Hill, New York, 2013, p. 628