Alibaba Cloud provides a default, free recursive DNS resolution service for endpoints such as Elastic Compute Service (ECS) instances and cloud containers in virtual private clouds (VPCs). This recursive DNS service interacts with external third-party DNS systems. Alibaba Cloud does not guarantee an SLA for DNS unavailability caused by external network issues or failures of external third-party DNS services.
Limits
Limit | Limit Threshold |
Total DNS queries per ECS instance in a VPC | 5,000 queries/second |
Total DNS queries from all ECS instances in a VPC | Unlimited |
External recursive queries per ECS instance in a VPC | 600 queries/second |
Total external recursive queries from all ECS instances in a VPC | 5,000 queries/second |
If you encounter rate limiting on external recursive DNS queries, enable cache reserve for high-traffic domain names. This keeps their DNS records cached for longer periods and prevents resolution failures due to rate limits. For more information, see Add a cache reserve domain name (FQDN).