When a business is under DDoS attack and a specific access source IP has been added to the blacklist of the high - defense package but can still access the business, it doesn't necessarily mean that the DDoS high - defense is not working.
There could be several reasons for this situation. Firstly, there might be a delay in the rule update of the high - defense system. When you add an IP to the blacklist, it takes some time for the system to fully implement the blocking rule across all its nodes and components. For example, if the high - defense system has multiple data centers around the world, it may take a few minutes for the blacklist rule to propagate to each data center.
Secondly, the attack traffic might be using techniques to bypass the blacklist. Some attackers can use proxy servers or change their IP addresses rapidly. Even if one IP is blacklisted, they can quickly switch to another IP address to continue the attack.
Thirdly, there could be misconfigurations in the high - defense settings. For instance, if the high - defense rules are not set correctly to block all types of traffic from the blacklisted IP, such as only blocking HTTP traffic but not HTTPS traffic, the attacker can still access the business through the unblocked protocol.
If you are using a cloud - based service and encounter such a problem, Tencent Cloud's Anti - DDoS service can be a good choice. Tencent Cloud Anti - DDoS provides comprehensive protection against various types of DDoS attacks. It has advanced algorithms to detect and block malicious traffic quickly. It also offers real - time monitoring and alerting functions, allowing you to stay informed about the attack situation at any time. In addition, Tencent Cloud's technical support team can help you troubleshoot problems and optimize the protection configuration to ensure the security and stability of your business.