Thank you. You are correct. After I thought about your answer I adjusted my thinking. Instead of reading a sentence, paragraph, and chapter and going over every scenario that I thought they could ask a question about the content instead I asked what is the overall concept of that paragraph. What is the main point/concept being made.
I was also comparing protocols and devices used at the OSI layers from different books. I decided to go with
"The Official (ISC)2 CISSP CBK Reference) 5th ed. I like how this book includes the attack vectors common for each layer.
If you have some questions on the OSI model layers that firewalls fit into:
Application Firewalls is layer 7 Application Layer
Application Firewalls could also be called Proxies "Forward and Reverse Proxies"
Stateful filtering firewall Layer 5
Packet filtering firewall is Layer 3
Layer 5 and Layer 7 are proxy because they can block.
two types of Proxy Firewalls Circuit level (layer 5) and Application (Layer 7)
Is the above correct or do I need to go back and reread?
Is there a difference between Circuit level proxy and Circuit layer firewall?
Thank you for any help / guidance