Help Center/ Domain Name Service/ User Guide/ Private DNS Resolution/ Recursive Resolution
Updated on 2026-09-08 GMT+08:00
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Recursive Resolution

Overview

A private DNS server provides domain name resolution services (including resolution of private domain names, cloud service domain names, and Internet domain names) for compute nodes such as VMs and containers in a VPC. When resolving Internet domain names, the private DNS server serves as the recursive DNS server and interacts with third-party DNS servers. Recursive resolution cannot guarantee an SLA due to uncontrollable factors such as the stability of external networks and the reliability of third-party DNS servers.

Constraints

Item

Threshold

Description

Maximum number of requests for a single ECS in a VPC

2,000 requests per second

For a single ECS in a VPC, the maximum number of requests is 2,000 per second. If the number of requests exceeds this, extra requests may not be handled.

If your services initiate an enormous volume of concurrent requests, enable DNS caching to improve lookup efficiency.

Total number of requests for all ECSs in a VPC

Unlimited

-

Maximum number of recursive resolution requests for a single ECS in a VPC

600 requests per second

For a single ECS in a VPC, the maximum number of external recursive requests is 600 per second. If the number of requests exceeds this, extra requests may not be handled. If your VM requests a swarm of random subdomain names, DNS resolution will be frozen.

If your services initiate an enormous volume of concurrent requests, enable DNS caching to improve lookup efficiency.

Total number of recursive requests for all ECSs in a VPC

5,000 requests per second

For all ECSs in a VPC, the maximum number of external recursive requests is 5,000 per second. If the number of requests exceeds this, extra requests may not be handled.

If access to a large number of Internet domain names is required, some domain names may not be accessible due to traffic limit. To avoid this, submit a service ticket in advance.

Maximum number of recursive resolution requests for a single domain name in a VPC

50 requests per second

For a single domain name (for example, example.com) and its subdomains in a VPC, the maximum number of external recursive requests is 50 per second. If the number of requests exceeds this, extra requests may not be handled.
Parent Topic: Private DNS Resolution