Involved services
Public DNS is a global public recursive domain name resolution service for all Internet users. This speed limit only affects the Public DNS Free Edition (223.5.5.5, 223.6.6.6, etc.). This announcement does not affect scenarios such as configuring resolution records and authoritative DNS resolution after domain name registration. There is no change in the use of authoritative resolution.
Affected users
Users who access the Public DNS Free Edition, including recursive DNS request traffic using protocols such as DoH, DoT, UDP, and TCP. (This announcement is not related to Alibaba Cloud's public authoritative DNS resolution service, and there is no change in the public authoritative DNS business logic)
Effective time
Starting from midnight on September 30, 2024
Notification content
To ensure the stable operation of the system, starting from September 30, 2024, the Free Edition of Public DNS (223.5.5.5, 223.6.6.6, etc.) will implement intelligent traffic control measures for resolution requests. Public DNS will continue to provide high-quality basic recursive resolution services for free users. However, in high concurrency resolution scenarios that pose a threat to the stable operation of the system, the free traffic of Public DNS may be temporarily limited by the number of concurrent requests per source IP per recursive node. This concurrent request limit is not a fixed threshold. The specific speed limit value will be adjusted according to network load conditions and the overall service quality of Public DNS to ensure the stability and user experience of the overall Public DNS service. The Free Edition of Public DNS does not promise availability guarantees.
Recommended solutions
You can enable terminal caching policies.
For example, Linux systems can enable the nscd caching service.
Enterprise customers with high business request volumes who need service availability guarantees can upgrade to the paid version of Public DNS.
The paid version of Public DNS promises 99.99% resolution service availability, and paid users will not be subject to speed limits. The promotional activities for the paid version are as follows:
For users accessing via DoH/DoT: The paid version of Public DNS provides 10 million free HTTP resolutions per month for all connected customers, which is sufficient for daily use by small enterprise applications. For traffic exceeding the free quota, we offer two billing models: pay-as-you-go and data transfer plan. For more information, see Product Billing.
For users accessing via UDP/TCP: If your business domain name resolution requests have high concurrency, you can protect against speed limits by attaching public egress IP addresses. The system will prioritize protecting DNS requests from these IPs in extreme scenarios. We also have private DNS software that can be independently deployed in office networks, IDCs, public clouds, and other environments for use as recursive or authoritative DNS. (DingTalk consultation: behladu)