Intelligent resolution

Overview

Intelligent resolution identifies visitor origin and returns the most appropriate IP address. For example, if www.cloud-example.com has servers at China Unicom, China Mobile, and China Telecom, intelligent resolution routes each visitor to their ISP's server.

How it compares to traditional DNS:

	Intelligent resolution	Traditional DNS resolution
Configuration	Set the resolution request source Default to the China Unicom IP address (192.x.x.1). Set the resolution request source China Mobile to the China Mobile IP address (192.x.x.2). Set the resolution request source China Telecom to the China Telecom IP address (192.x.x.3).	Point the domain to the China Unicom IP address (192.x.x.1). Map the domain name to the mobile IP address (192.x.x.2). Point the domain to the China Telecom IP address (192.x.x.3).
Resolution result	Alibaba Cloud DNS identifies the visitor's source: Returns 192.x.x.2 to visitors from China Mobile. Returns 192.x.x.3 to visitors from China Telecom. Returns 192.x.x.1 to visitors from all other sources.	Traditional DNS does not identify visitor source: It returns all three IPs (192.x.x.1, 192.x.x.2, 192.x.x.3) to the local DNS resolver, which randomly or preferentially selects one. This may cause cross-ISP access.

How it works

Alibaba Cloud DNS identifies visitor location by detecting the egress IP of their local DNS resolver (not the visitor's device IP). The process varies by whether the resolver supports EDNS:

Scenario 1: Local DNS supports EDNS

When the local DNS resolver supports edns-client-subnet, Alibaba Cloud DNS checks for a client IP in the extension. If found, it uses that IP to determine visitor location. Otherwise, it falls back to the resolver's egress IP.

Scenario 2: Local DNS does not support EDNS

When the local DNS resolver does not support EDNS, it sends iterative queries to Alibaba Cloud DNS, which determines visitor location from the resolver's egress IP and returns the matching result.

Scenario 3: Local DNS uses forwarding

When a local DNS resolver forwards the query to a secondary node (forwarder), that forwarder queries Alibaba Cloud DNS. In this case, Alibaba Cloud DNS returns results based on the forwarder's location, not the original resolver's location.

Supported lines

Lines use a multi-level classification. Configure resolution rules at any level from top-level categories down to specific child classes.

Line	Level 1 category	Level 2 category	Level 3 category
Region	China, Overseas	Northeast China, North China, Asia, Europe, etc.	Beijing
ISP	China Mobile, China Unicom, etc.	Northeast China, North China, etc.	Beijing
Cloud provider	Alibaba Cloud	China, Overseas	Northeast China, North China, etc.
Search Engine	Google, Bing	China, Overseas	-
Custom	Custom classification	-	-

Detailed line descriptions are available in Lines.

Resolution priority

When multiple rules match a visitor, Alibaba Cloud DNS applies the following priority:

1. Line priority (highest to lowest): Custom > Search Engine > Cloud Provider > ISP > Region > Default

2. Within each line category, more specific rules take precedence. For example, Beijing has higher priority than North China, and North China has higher priority than China.

3. Always configure a Default line. The Default line is the fallback when no other rule matches. Set at least one DNS record for the Default line to prevent resolution failures.

Pricing and editions

• Enterprise Standard and Enterprise Ultimate: All lines are available. To purchase, see Purchase and attach domain names.

• Free Edition: Only top-level line categories are available (such as Level 1 region lines). Granular line classifications are not supported.

Examples

Example 1: Route by ISP

Assume www.cloud-example.com has servers at three ISPs: China Telecom, China Unicom, and China Mobile. Target routing:

• Visitors from China Unicom or other ISPs receive 192.168.0.1 (China Unicom server)

• Visitors from China Mobile receive 192.168.0.2 (China Mobile server)

• Visitors from China Telecom receive 192.168.0.3 (China Telecom server)

Steps:

1. Go to the Alibaba Cloud DNS - Public Zone page. Find the domain that you want to manage and click its name. Then, click the Settings tab.

2. On the Settings tab, click Add Record.

3. Add three DNS records as described in the following table:

   Host	Type	Request source	Record value
   www	A	China Mobile	192.168.0.2
   www	A	China Telecom	192.168.0.3
   www	A	Default	192.168.0.1

Example 2: Route by region

Assume test.cloud-example.com has servers in three regions: Zhejiang (South China), Beijing (North China), and a default location. Target routing:

• Visitors from regions other than South China or North China receive 192.168.0.7 (default server)

• Visitors from South China receive 192.168.0.8 (Zhejiang server)

• Visitors from North China receive 192.168.0.9 (Beijing server)

Steps:

1. Go to the Alibaba Cloud DNS - Public Zone page. Find the domain that you want to manage and click its name. Then, click the Settings tab.

2. On the Settings tab, click Add Record.

3. Add three DNS records as specified in the following table.

   Host record	Type	Request source	Value
   www	A	China_South China	192.168.0.8
   www	A	China_North China	192.168.0.9
   www	A	Default	192.168.0.7

FAQ

Intelligent resolution FAQ