mojira.dev
MC-297458

SRV Records Not Respecting Priority/Weight for Traffic Distribution in Minecraft Client

Description:

When hosting a Minecraft server, I configured two IP addresses and a non-standard port to ensure stability and security. I set up SRV records for the domain "_minecraft._tcp.mc.**.**" with one IP assigned priority 10 and the other priority 20. However, when the second IP address is unavailable (access denied), there is a 50% failure rate when connecting via the domain.  

Expected Behavior:

Clients should prioritize the lower-priority IP (priority 10) as per SRV record specifications. If this IP becomes unavailable, the higher-priority IP (priority 20) should be used instead.  

Observed Behavior:

During testing, both IPs are selected with equal probability, regardless of their priority/weight settings. This suggests the Minecraft client may not fully implement SRV record resolution logic for prioritization and weighted load balancing.  

Reproduction Steps:

  1. Configure two SRV records for "_minecraft._tcp.mc.**.**" with distinct priorities (e.g., 10 and 20).  

  1. Block access to the higher-priority IP (priority 20).  

  1. Attempt to connect to the domain.  

Additional Notes:

This issue could impact server redundancy and failover reliability. The SRV record behavior described aligns with RFC 2782 standards for DNS SRV records, which Minecraft clients should adhere to.  

Request:

Please investigate whether the client's SRV record parsing logic correctly handles priority/weight parameters. Thank you for your attention to this matter.  

The English text was generated by Qwen3.If the expression is not clear, please let me know, I can explain in detail.

在我开mc服务端时,我为了保证服务稳定性与安全性,用了两个IP和一个非标端口,然后用srv记录把两个IP都绑到了一个域名“_minecraft._tcp.mc.**.**”上,一个IP优先级设为10,另一个IP优先级为20。

当我关闭第二个IP地址访问权限时,这个域名会有50%概率连不上。

正常情况下,应该以优先级数值低的地址优先,而据我测试,两个地址分配到的概率相同。

我认为可能是minecraft客户端对srv记录解析不完整,未能按优先级和权重设定去连接服务器。

Linked issues

Comments 1

Thank you for your report!
We are tracking this issue in MC-49826 and MC-151920, so this ticket is being resolved and linked as a duplicate.

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Yuheng

(Unassigned)

Unconfirmed

(Unassigned)

1.21.5

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