Requests sent to Alibaba Cloud Content Delivery Network (CDN) through the application layer are recorded in the access log of Alibaba Cloud CDN. These requests are counted and billed. If your request fails to retrieve resources, you are still charged for the request because the corresponding CDN node has parsed the request at the application layer. If you send an HTTPS request, Alibaba Cloud CDN must consume CPU resources to process TLS handshakes. This topic provides answers to some commonly asked questions about the billing of requests.
- The whitelist, blacklist, and rate limiting features provided by Alibaba Cloud CDN regulate access control at the application layer. The implementation of these features is different from that of the protection features, such as firewalls, at the network or transport layer.
- For more information about the billing of requests, see Billing of value-added services.
A file has been cached on the client. Is the request billed when the client requests the file from the CDN node for the second time?
Yes, the request is billed. If the file has been cached on the client, the second time that the client requests the file from the CDN node, the CDN node returns a 304 status code to the client if the file has not been updated. In this case, you are charged for the request and the amount of network traffic generated by the request. Network traffic is generated because the CDN node returns a small packet to the client.
Am I charged if attackers send a large number of requests to my domain name?
- If the blacklist, whitelist, and rate limiting features are disabled, no IP address is blocked. A large number of requests are sent to CDN nodes and a large amount of network traffic is generated. These requests and network traffic incur a large amount of fees.
- If the blacklist, whitelist, or rate limiting feature is enabled, the specified IP addresses are blocked. The number of requests sent to CDN nodes and the amount of network traffic generated are significantly reduced. The amount of fees incurred by requests and network traffic is also reduced.