CND (312-38) Network Defense Simulation
In this simulation, you will analyze hardware-level redundancy strategies. Understanding RAID levels is critical for ensuring the Availability pillar of the CIA triad against hardware failures.
01. Network Scenario
An enterprise storage server hosting critical DNS and Active Directory logs is being configured for maximum performance and fault tolerance. The network administrator is evaluating different disk array configurations to ensure that even if a drive fails, the service remains reachable.
- • OS: Enterprise Linux (Storage Node)
- • Disk Count: 4x 2TB SAS Drives
- • Traffic Load: High Read/Write I/O
- • Redundancy for Parity information
- • Minimized single point of failure in the array
02. Traffic & Logs
[SYSTEM MONITOR] Storage Controller Status:
-- Physical Disk 0: ONLINE (Parity Data)
-- Physical Disk 1: ONLINE (Data)
-- Physical Disk 2: ONLINE (Data)
-- Physical Disk 3: ONLINE (Data)
[ALERT] Critical Error: Controller identifies dedicated Parity Disk (PD0) as failing.
[INFO] Attempting to read parity from alternate disks...
[ERROR] Parity recovery failed. Parity data is localized to a single failed volume.
[WARNING] Logical Volume status: CRITICAL - No parity protection for the parity disk itself.
03. Question
Which of the following types of RAID offers no protection for the parity disk?
Think about which RAID level uses a single, dedicated disk to store all parity bits for the entire array.
Expert Analysis
1. What is happening in the network
The system is using a RAID configuration that centralizes error-correcting data (parity) onto a single physical drive. When that specific drive fails, the entire parity mechanism is lost.
2. Identify attack or behavior
This is a hardware availability risk. While not a malicious attack, a failure of the dedicated parity drive creates a "Single Point of Failure" for the data recovery mechanism.
3. Why correct answer is correct
RAID 3 uses byte-level striping with a dedicated parity disk. Because the parity information is not distributed across multiple disks (unlike RAID 5), the parity disk itself has no redundancy or protection. If the parity disk fails, the system loses its ability to reconstruct data from the other disks.
4. Why others are wrong
- RAID 2: Uses bit-level striping with Hamming code for error correction, often across multiple disks (rarely used).
- RAID 1: Disk Mirroring. There is no parity; data is simply duplicated.
- RAID 5: Distributes parity across all drives in the array. If any one drive fails (including one containing parity bits for a specific block), the other drives contain enough data/parity to rebuild it.
5. Defensive Action
To improve defense-in-depth at the physical layer, migrate from RAID 3 to RAID 5 or RAID 6 to eliminate the dedicated parity disk bottleneck and ensure parity information is protected via distribution.
MINI LESSON: RAID Defensive Properties
- RAID 0 (Striping): Performance only. ZERO protection. No parity.
- RAID 3/4: Dedicated Parity. High performance for large files, but parity disk is a bottleneck and risk.
- RAID 5: Distributed Parity. Most common defensive choice for balancing performance and availability.
- RAID 6: Dual Parity. Can withstand two simultaneous disk failures.
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