Intelligent resolution routes visitors to the optimal server based on their geographic location, ISP, or device type. By returning location-specific IP addresses instead of random ones, it reduces latency, improves load times, and enhances user experience.
Overview
Intelligent resolution identifies where a visitor is coming from and returns the most appropriate IP address. For example, if your domain www.cloud-example.com has servers at three different ISPs, China Unicom, China Mobile, and China Telecom, intelligent resolution automatically routes each visitor to their ISP's server for faster access.
How it compares to traditional DNS:
Intelligent resolution | Traditional DNS resolution | |
Configuration |
|
|
Resolution result | Alibaba Cloud DNS identifies the visitor's source:
| Traditional DNS resolution does not identify the visitor’s source: It returns all three IP addresses, 192.x.x.1, 192.x.x.2, and 192.x.x.3, to the visitor's local DNS resolver. The resolver then randomly or preferentially selects one IP address to return to the visitor. This may cause cross-ISP access. |
How it works
Alibaba Cloud DNS identifies a visitor's location by detecting the egress IP address of their local DNS resolver (not the visitor's device IP address). The resolution process varies depending on whether the local DNS resolver supports EDNS:
Scenario 1: Local DNS supports EDNS
When the local DNS resolver supports the edns-client-subnet extension, Alibaba Cloud DNS first checks for a client IP address within this extension. If found, it uses that IP address to determine the visitor's location. If no IP address is found in the extension, Alibaba Cloud DNS falls back to using the resolver's egress IP address.
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. Alibaba Cloud DNS determines the visitor's location based on the resolver's egress IP address and returns the corresponding intelligent resolution result.
Scenario 3: Local DNS uses forwarding
When a user enters example.com in a web browser, the query goes to the local DNS resolver, which forwards the request to a secondary node (forwarder). This secondary node then queries Alibaba Cloud DNS. In this case, Alibaba Cloud DNS returns resolution results based on the geographic location of the forwarder, not the original local DNS resolver.
Supported lines
Lines are organized into a multi-level classification system. You can configure intelligent resolution rules based on top-level categories or their 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 | - | - |
For detailed descriptions of the lines, see Lines.
Resolution priority
When multiple resolution rules match a visitor, Alibaba Cloud DNS uses the following priority order:
Line priority (highest to lowest): Custom > Search Engine > Cloud Provider > ISP > Region > Default
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.
Always configure a Default line. The Default line acts as a fallback when no other rule matches. You must set at least one DNS record for the Default line to prevent resolution failures.
Pricing and editions
Intelligent resolution is free of charge. However, the available lines vary based on your subscription edition.
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 that your domain www.cloud-example.com has servers at three different ISPs: China Telecom, China Unicom, and China Mobile. You want to achieve the following routing behavior:
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:
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.
On the Settings tab, click Add Record.
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 that your domain test.cloud-example.com has servers in three regions: Zhejiang(South China) , Beijing (North China), and a default location. You want to achieve the following routing behavior:
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:
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.
On the Settings tab, click Add Record.
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