Denial of Service (DoS) and DDoS Attacks Explained

• Traffic comes from many different systems
• Attackers use a network of compromised devices

These compromised devices are often part of a:

• Botnet

DDoS attacks are harder to stop because:

• Traffic originates from many locations

Why DDoS Attacks Are More Dangerous

DDoS attacks are more dangerous because:

• They generate massive traffic volumes
• Blocking a single source is ineffective
• Attacks can last for long periods

Large organisations and public services are common targets because:

• Disruption causes significant damage

IB students should link DDoS attacks to scale and coordination.

Impact of DoS and DDoS Attacks

These attacks can cause:

• Website downtime
• Loss of revenue
• Reputational damage
• Service disruption

For critical systems such as:

• Banking platforms
• Government services
• Online education systems

availability is essential.

Why DoS and DDoS Are Hard to Prevent

DoS and DDoS attacks are difficult to prevent because:

• Attack traffic resembles legitimate traffic
• Attackers use many devices
• Systems must remain publicly accessible

Blocking all traffic is not an option, as it would deny service to real users.

Mitigating DoS and DDoS Attacks

Common mitigation strategies include:

• Traffic filtering
• Rate limiting
• Load balancing
• Use of specialised DDoS protection services

IB students should understand that:

• Mitigation reduces impact
• Attacks may not be fully prevented

DoS Attacks and Risk Assessment

DoS and DDoS attacks are:

• High-impact threats
• Especially risky for online services

Risk assessments often prioritise:

• Availability protection
• Redundancy and resilience

Common Student Mistakes

Students often:

• Confuse DoS with hacking or data theft
• Ignore availability
• Forget distributed nature of DDoS
• Describe attacks too vaguely

Clear explanation of intent and impact earns marks.

How This Appears in IB Exams

IB questions may ask students to:

• Define DoS or DDoS attacks
• Compare the two
• Explain their impact on systems
• Suggest mitigation strategies

Explanation matters more than technical detail.

Final Thoughts

Denial of Service attacks aim to make systems unavailable by overwhelming resources, while Distributed Denial of Service attacks achieve the same goal using many compromised devices. These attacks target availability and can disrupt even secure systems.

Understanding DoS and DDoS attacks allows IB Computer Science students to explain why availability is a critical part of system security — exactly what examiners expect.

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