When you host a website on multiple Alibaba Cloud ECS instances, you can distribute traffic to your websites across a few instances by using the Alibaba Cloud DNS load balancing feature. With Alibaba Cloud DNS load balancing you can scale your websites and create high availability for your services.
How DNS Load Balancing Works
Round robin load balancing
Round robin method is a simple way to do DNS load balancing. When DNS receiving requests from a visitor, the authoritative DNS servers poll the three A records according to the weights of the DNS records (default to 1:1:1).
Every requests will equally distribute to all ECS instances.
Weighted load balancing
When the records are configured with different weights (for example 2:1:1), the DNS server responds 50% of the time with the ECS-1 IP address, 25% of the time with the ECS-2 IP address, and 25% of the time with the ECS-3 IP address.
How to Configure DNS Load Balancing
Firstly, login to Alibaba Cloud DNS console, add A records of the ECS instances.
Now, at Traffic Steering section, enable DNS load balancing and set different weight values for different DNS records.
The newly added record takes effect in seconds, and is enabled by default.