What are the differences between route-based resolution and weighted resolution in intelligent DNS resolution?

　　Many users of Smart DNS will encounter the "Route-Based Resolution" and "Weighted Resolution" functions. While both seem to direct different users to different IPs, their underlying logic and application scenarios are completely different. Route-based resolution addresses the question of "which server a user should go to," while weighted resolution addresses the question of "how traffic is distributed among multiple servers." One "selects routes based on origin," and the other "allocates traffic proportionally." Each has its own function and can be used in combination.

　　Route-Based Resolution: "Selecting Routes" Based on User Origin

　　The core logic of route-based resolution is to identify the user's origin characteristics and return the most matching IP address. When Smart DNS receives a domain name query request, it analyzes the requester's IP address, determines its ISP type (e.g., China Telecom, China Unicom, China Mobile) and geographical location (e.g., province, country), and then returns the corresponding server IP according to preset route rules.

　　The most typical application scenario is solving the problem of slow access across ISPs. If your business has servers deployed in both China Telecom and China Unicom data centers, segmented DNS resolution ensures that China Telecom users are resolved to China Telecom IPs, and China Unicom users to China Unicom IPs, avoiding detours and significantly reducing latency. In short, segmented DNS resolution answers the question "Which node should this user go to?"—it directs users to different "doors," each leading to a different server cluster.

　　DNS.COM's intelligent line resolution feature supports differentiating visitor origins by dimensions such as ISP and region, and provides different resolution responses for access requests to the same domain name, pointing to different server IP addresses.

　　Weighted DNS Resolution: Proportionally Distributing Traffic

　　Weighted DNS resolution solves another type of problem: how to proportionally distribute traffic when there are multiple server IPs under the same line.

　　Its working principle is as follows: Multiple IP addresses are configured for the same host record and the same source of the DNS resolution request, and a weight value (usually 0-100) is assigned to each IP. The DNS server then randomly returns one of these IPs according to its weight ratio in the response. The documentation explicitly states that when load balancing is enabled, each DNS query will "randomly select one record value to return based on the weight ratio of each record value (instead of returning all records)."

　　Weighted DNS resolution answers the question of "how much traffic should be allocated to this server and how much to that server"—it doesn't change which network a user is assigned to, but rather distributes users across different physical servers within the same network according to a set ratio.

　　Alibaba Cloud's internal DNS resolution weight configuration instructions state that weight values ​​can be set from 0-100, with a default weight ratio of 1:1. If a record's weight is set to 0, that record will not be returned during resolution; if all weights are set to 0, all record values ​​will be returned.

　　Both can be used in combination.

　　Network-based DNS resolution and weighted DNS resolution are not mutually exclusive; they can work together to achieve more granular traffic management.

　　Typical Scenario: Suppose you have deployed two servers, A and B, in Beijing with different performance levels (A's performance is 3 times that of B). You want Beijing Telecom users to access both servers, but with traffic distributed in a 3:1 ratio. Implementation: First, create a "Beijing Telecom" line using line-specific DNS resolution; then add two A records under this line, pointing to the IPs of A and B respectively, and setting their weights to 3 and 1.

　　When to Use Which?

　　Scenarios where line-specific DNS resolution is preferred:

　　Users are distributed across different carriers or regions and need to access the nearest server.

　　Multiple regional servers are deployed, and cross-network latency needs to be reduced.

　　For global users, traffic needs to be split between domestic and international access.

　　Scenarios where weighted DNS resolution is preferred:

　　Multiple servers on the same line with inconsistent performance.

　　During a canary release, a small number of users want to experience the new version first.

　　Rolling upgrades or maintenance of servers are required, gradually switching traffic.

　　In short: Line-specific DNS resolution solves the routing problem of "who comes and who goes," while weighted DNS resolution solves the load balancing problem of "how traffic is distributed." Both have their own functions, but they can also be used together to form the fine-grained traffic scheduling capabilities of intelligent DNS.