Glossary Term

DDOS ATTACK

A flood of malicious traffic from many sources aimed at knocking a site or service offline.

Definition

A DDoS (Distributed Denial of Service) attack is a flood of malicious traffic from many sources at once, aimed at overwhelming a website, server or network so legitimate visitors cannot get through. Attackers control botnets of compromised computers, routers and IoT devices, sometimes hundreds of thousands of them, to send millions of requests per second, exhaust bandwidth or fill connection tables faster than a server can clear them. Attacks range from short bursts under a minute to sustained floods lasting days, and some recorded events have exceeded several terabits per second. DDoS protection works by detecting and filtering the malicious traffic at the network edge, before it reaches the origin server, usually through a CDN or a dedicated scrubbing network. It does not fix application bugs or stop targeted account takeovers, only volumetric and connection-based flooding. Cloudflare offers free DDoS protection on every plan, including its free tier; AWS Shield, Akamai Prolexic and Imperva cover enterprise-scale needs.

How it works

DDoS attacks come in layers: layer 3/4 attacks (UDP floods, SYN floods) try to saturate bandwidth or connection state; layer 7 attacks mimic real users to exhaust application resources. Strong protection covers both, with always-on monitoring rather than reactive scrubbing.

Why it matters

Any site can be attacked, and the cost of being unprotected is hours or days of downtime. Game servers, news sites, controversial content and competitors' targets are especially exposed. Layer-3/4 protection should be free and included; charging extra for basic DDoS protection is a red flag.

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Frequently Asked Questions

How do I stop a DDoS attack?

Front your origin with a CDN or DDoS-protection service (Cloudflare, AWS Shield, Akamai). They absorb and filter attack traffic at the edge before it reaches your server.

Is DDoS protection free?

Cloudflare's free plan includes always-on layer-3/4 and layer-7 DDoS protection that suits most sites. Enterprise needs and very large attacks usually require a paid tier.

What's a common mistake that leaves sites exposed despite having DDoS protection?

The biggest mistake is leaving the origin server's real IP address exposed, for example through old DNS records, direct-connect APIs or a mail server on the same box. Attackers scan for it and bypass the CDN entirely. Proxy every public-facing service through the provider and rotate the origin IP if it has ever been exposed.

How can I check if my DDoS protection is actually working?

Confirm DNS resolves to the provider's IP ranges rather than your origin, then run a controlled load test with the provider's permission. Review dashboard logs during normal traffic; near-zero blocked legitimate requests alongside normal site access confirms filtering is active without over-blocking real users.

When should I pay for enterprise DDoS protection instead of a free CDN tier?

Free CDN tiers handle most volumetric and layer-7 floods for typical sites. Move to a paid tier such as AWS Shield Advanced or Akamai Prolexic when you need guaranteed SLAs, 24/7 incident response, custom mitigation rules for a specific application, or defence against attacks reaching tens of gigabits per second.

Related Terms

WAF
Web Application Firewall: filters malicious requests (SQL injection, XSS, bot abuse) before they hit your app.
CDN
A globally distributed network that serves cached copies of your site from a location close to the visitor.
Uptime
The percentage of time a site or service is reachable; 99.9% is the common production minimum.
Bandwidth
The amount of data your hosting plan can transfer per month, often the biggest cost driver at scale.
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