Lesson 2-2 explained: Network Security Design

Lesson summary

A single lock on the front door is not enough: if it is picked, everything inside is exposed. For this reason, modern network security uses several layers, so that even when one defense is breached, the next one still protects the system.

Takeaway: Layer your defenses — firewall, VPN, DMZ, endpoints — and verify every access (zero trust). One breach is then far less likely to expose the whole network.

Key terms

• Firewall
• VPN
• DMZ
• Defense in depth
• Zero trust
• Perimeter

Textbook page: Arabic book 38 · English book 41

Free questions on this lesson

From the textbook question bank. Think of the answer first, then open it.

1. 1. What is a firewall?

   • A system that allows or denies traffic by preset rules
   • An encrypted private line linking branches online
   • A zone where public servers sit apart from inside
   • Software that deletes virus-infected files automatically
   Answer

   Correct answer: A system that allows or denies traffic by preset rules

   A firewall sits at a network's entry/exit point and allows or denies communication by preset rules.

   1. The Role of Firewalls · page 42

2. 2. According to the DMZ figure, what happens if an attacker attacks a public server?

   • The Internet stops working
   • All public servers are deleted
   • The internal network is still protected
   • The database is exposed at once
   Answer

   Correct answer: The internal network is still protected

   As the figure says: if a public server is attacked, the internal network is still protected.

   Figure: DMZ network configuration · page 43

3. 3. Comparing traditional security and zero trust, who is verified under zero trust?

   • Only devices; users are always trusted
   • Nobody; one firewall check is enough
   • External users, internal users and devices, all of them
   • Only external users when they cross the perimeter
   Answer

   Correct answer: External users, internal users and devices, all of them

   Under zero trust, external users, internal users and devices are all verified.

   Figure: Traditional security vs zero trust · page 44

Lessons in this chapter 2: Cybersecurity

1. 2-1 Cryptographic Technologies and Authentication
2. 2-2 Network Security Design
3. 2-3 Incident Response and Risk Management