CDN, or Content Delivery Network, is a service that can maintain website content availability despite network issues like hardware failures or network congestion. It does this through load balancing, which distributes network traffic across multiple servers. This means that spikes in traffic can be managed efficiently, mitigating potential service interruptions. Much like how a highway can become congested with too many vehicles, load balancing functions similarly to a real-time map app that redirects traffic to other routes, thus ensuring that all traffic moves more efficiently.
CDNs also use intelligent failover, a feature that automatically offloads tasks to a standby system or another machine with available capacity to ensure near-continuous availability.
The purpose of failover is to prevent traffic loss when a server is unavailable. CDNs use an Anycast network, which allows multiple machines to share the same IP address. Routers direct the request to the closest machine on the network. Anycast network can respond to an outage similarly to load balancing where data is routed away from the failing location and sent to a functioning data center. This allows CDN to respond quickly and efficiently in case of extraordinary demand such as during a DDoS attack.
CDN increases reliability by maintaining servers across many data centers, which enables them to find the optimal route to deliver content as quickly as possible, reduce latency, and mitigate the impact of network problems. CDNs also control their own network connections by placing servers in strategic locations, such as Internet exchange points (IXPs), to optimize the route and reduce latency. The use of CDNs is increasingly important as DDoS attacks pose a substantial threat to the reliability of Internet properties.
Looking to learn more? We suggest heading over to Cloudflare’s Learning Center for an in-depth look at DNS flood attacks.
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