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What Is DoS vs DDoS – Availability First
What Is DoS vs DDoS – Availability First DoS (Denial of Service): one source floods a website so real users cannot use it. DDoS (Distributed DoS): many computers attack together. They are often a botnet (hacked devices controlled by one attacker). Both attack availability : the site must be up for r
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What this card says
What each one is
DoS (Denial of Service): one source floods a website so real users cannot use it.
DDoS (Distributed DoS): many computers attack together. They are often a botnet (hacked devices controlled by one attacker).
What it attacks
Both attack availability: the site must be up for real users.
They do not steal passwords. They just block access.
Real incident
On 21 October 2016, the DNS company Dyn was hit by a huge DDoS from the Mirai botnet of hacked IoT devices (cameras, routers).
Many popular websites became hard to reach.
Defence
Change default passwords on IoT devices.
Use DDoS protection, rate limits and more than one DNS provider for important sites.
| Class | Simple idea | Blue focus |
|---|---|---|
| Volumetric | Fill the pipe (Gbps / packets per second) | ISP / cloud scrubbing, Anycast, capacity |
| Protocol | Abuse handshake / state (SYN flood, etc.) | SYN cookies, firewall state limits |
| Application-layer | Cheap requests that hurt CPU/workers (HTTP flood,… | Rate limit, WAF, timeouts, sizing |
Learn more in the lesson: 40.1 What Is DoS vs DDoS – Availability First