Chapter 2 of 518% of exam

Security Architecture and Design

This chapter covers how to design resilient, defensible systems and networks. You will learn foundational principles like zero trust, defense in depth, and least privilege, along with segmentation, cloud models, and virtualization. Good architecture makes attacks harder and limits damage when defenses fail.

Core Design Principles

Security architecture rests on a few enduring principles that reduce risk regardless of specific technology. Applying them consistently produces systems that resist compromise and contain incidents.

Zero trust
Trust nothing by default; verify every request by identity, device posture, and context, even inside the perimeter.
Defense in depth
Layer independent controls so no single failure causes a breach; each layer backs up the others.
Least privilege
Grant only the minimum access needed for a role, shrinking the attack surface and limiting damage.
Least functionality
Run only required services and features; disable unnecessary ports and software to reduce exposure.
Implicit deny
Block anything not explicitly permitted so unknown traffic is rejected by default.

Network Segmentation and Zones

Dividing networks into controlled zones limits how far an attacker can move after gaining a foothold. Boundaries between zones enforce policy and contain breaches.

Segmentation
Separate systems into zones with VLANs and firewalls so a compromise cannot spread freely.
Screened subnet
Place public-facing servers in a DMZ isolated from the internal network by additional filtering.
Microsegmentation
Apply fine-grained per-workload policies, a key enabler of zero trust in data centers and clouds.
Air gap
Physically isolate the most critical networks from untrusted ones to remove remote attack paths.
Jump server
Funnel administrative access through a hardened, monitored bastion host into sensitive segments.

Cloud and Virtualization

Modern architectures rely heavily on cloud services and virtualization, which change where security responsibilities lie. Understanding the models prevents dangerous misconfigurations.

Service models
IaaS gives the most customer control, PaaS shares it, and SaaS shifts most responsibility to the provider.
Shared responsibility
The provider secures the underlying infrastructure while the customer secures data, identities, and configuration.
Virtualization
A hypervisor runs multiple isolated VMs on one host; hardening the hypervisor is critical.
Containers
Package apps with dependencies sharing the host kernel; lighter than VMs but with weaker isolation.
Sandboxing
Run untrusted code in an isolated environment to analyze it without risking the host.

Resilience and Availability

Availability is a core security goal, so architecture must tolerate failures and attacks. Redundancy and recovery design keep services running through disruption.

Redundancy
Duplicate critical components so no single point of failure causes an outage.
Failover
Automatically shift workloads to a standby when the primary fails; test it regularly.
Load balancing
Distribute traffic across servers to improve performance and tolerate individual node failures.
High availability
Combine redundancy and failover to meet uptime targets for critical services.
Honeypots
Deploy decoys to detect and study attackers while diverting them from real assets.
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Threats, Attacks, and Social Engineering
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Implementation: Cryptography, Identity, and Secure Protocols

Last updated: July 2026

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