Traditional Domain Name System (DNS) resolution does not distinguish between visitor sources and returns a random IP address. In contrast, intelligent DNS resolution identifies the visitor's source to return a specific IP address. This method directs visitors to a designated IP address, which reduces resolution latency and improves website access speed.
Function introduction
For example, assume that the domain name www.cloud-example.com resolves to three IP addresses: one for China Unicom, one for China Mobile, and one for China Telecom. You can then implement proximity-based resolution.
Intelligent DNS resolution | Traditional DNS resolution | |
Parser configuration |
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Resolution effect | Alibaba Cloud DNS determines the visitor's source:
| Traditional DNS resolution does not determine 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 server. The local DNS server then randomly selects or chooses the best IP address to return to the visitor. Traditional DNS resolution may cause cross-network access. |
How it works
Alibaba Cloud DNS determines the visitor's source by identifying the egress IP address of the local DNS server, not the IP address of the client. The following three scenarios describe how this works:
The local DNS server supports EDNS
Alibaba Cloud DNS supports the edns-client-subnet (ECS) extension. When Alibaba Cloud DNS receives a DNS query, it first checks for an IP address in the ECS extension. If an IP address is found, Alibaba Cloud DNS uses it to determine the visitor's location. Otherwise, it uses the egress IP address of the local DNS server.
The local DNS server does not support EDNS
The local DNS server sends an iterative query to Alibaba Cloud DNS. Alibaba Cloud DNS then uses the egress IP address of the local DNS server to determine the visitor's location and provide an intelligent resolution.
The local DNS server indirectly supports EDNS
When a user enters example.com in a web browser, the browser sends a query to the local DNS server. The local DNS server forwards the request to a secondary node. The secondary node then sends the request to Alibaba Cloud DNS. In this case, Alibaba Cloud DNS returns a specific resolution result based on the geographic location of the secondary node.
Supported lines
Lines are organized into multiple levels. You can configure intelligent resolution rules based on level 1 categories or their child classes.
Line | Level 1 category | Level 2 category | Level 3 category |
Region | Mainland China, Outside Mainland China | Northeast China, North China, Asia, Europe, etc. | Beijing |
Carrier | China Mobile, China Unicom, etc. | Northeast China, North China, etc. | Beijing |
Cloud provider | Alibaba Cloud | Mainland China, Outside Mainland China | Northeast China, North China, etc. |
Search engine | Google, Bing | Mainland China, Outside Mainland China | - |
Custom | Custom categorization | - | - |
For more information, see Line types.
Priority
Line priority is as follows, from highest to lowest: Custom > Search Engine > Cloud Provider > Carrier > Region > Default.
Within each line category, more specific lines have higher priority. For example: Beijing > North China > Mainland China.
The Default line has the lowest priority and provides a fallback resolution. Add a DNS record with the resolution line set to Default to prevent resolution failures when a request does not match any other line.
Pricing
The intelligent DNS resolution feature is free of charge. However, the available lines vary based on your Paid Edition.
Enterprise Standard Edition and Enterprise Ultimate Edition: All lines are available. To purchase an edition, see Purchase and bind domain names.
Free Edition: Provides access to some level 1 categories, such as Region Lines. Access to other categories is restricted.
Configuration scenarios
Scenario 1: Intelligent resolution based on carrier lines
If your domain name www.cloud-example.com resolves to three IP addresses for China Telecom, China Unicom, and China Mobile networks, you can configure DNS records to achieve the following results:
Alibaba Cloud DNS returns
192.168.0.1to visitors from carriers other than China Mobile or China Telecom.Alibaba Cloud DNS returns
192.168.0.2to visitors from China Mobile.Alibaba Cloud DNS returns
192.168.0.3to visitors from China Telecom.
On the Alibaba Cloud DNS - Public Authoritative Zone page, click the target domain name to go to the Settings page.
On the Settings page, click Add Record.
Add three DNS records as described in the following table.
Host Record
Type
Parsing the request source
Value
www
A
China Mobile
192.168.0.2
www
A
China Telecom
192.168.0.3
www
A
Default
192.168.0.1
Scenario 2: Intelligent resolution based on region lines
If your domain name test.cloud-example.com resolves to three IP addresses in Zhejiang, Guangdong, and Beijing, you can configure DNS records to achieve the following results:
Alibaba Cloud DNS returns
192.168.0.7to visitors from regions other than South China or North China.Alibaba Cloud DNS returns
192.168.0.8to visitors from the South China region.Alibaba Cloud DNS returns
192.168.0.9to visitors from the North China region.
Procedure
On the Alibaba Cloud DNS - Public Authoritative Zone page, click the target domain name to go to the Settings page.
On the Settings page, click Add Record.
Add three DNS records as described in the following table.
Hostname
Type
Parsing the request source
Value
www
A
Mainland China_South China
192.168.0.8
www
A
Mainland China_North China
192.168.0.9
www
A
Default
192.168.0.7