A distributed denial-of-service (DDoS) attack is where a large number of computers or devices, usually controlled by a single attacker, attempt to access a website or online service all at once. This flood of traffic can overwhelm the website's origin servers, causing the site to slow down or even crash.
sequenceDiagram; participant User; participant Website; participant Server; participant Botnet; User->>Website: Requests to access site Website->>Origin Server: Processes user requests Botnet->>Origin Server: Sends a flood of traffic Origin Server-->>Website: Slows down due to traffic overload Origin Server-->>User: Unable to respond to user requests
Common signs that you are under DDoS attack include:
- Your site is offline or slow to respond to requests.
- Unexpected spikes appear in the graph of Requests Through Cloudflare or Bandwidth in your Cloudflare Analytics app.
- Strange requests appear in your origin web server logs that do not match normal visitor behavior.
If you are currently under DDoS attack, refer to our guide onresponding to a DDoS attack.
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