# rpc 错误：代码 = Unavailable 描述 = 无法解析服务名称：没有这样的主机

- **ID:** `go/grpc-unavailable-dns-resolution`
- **领域:** go
- **类别:** network_error
- **验证级别:** ai_generated
- **修复率:** 80%

## 根因

DNS 解析失败，因为目标主机名不存在或 DNS 服务器不可达。

## 版本兼容性

| 版本 | 状态 | 引入 | 弃用 |
|------|------|------|------|
| 1.56.x | active | — | — |
| 1.57.x | active | — | — |

## 解决方案

1. **** (85% 成功率)
   ```
   resolver := &customResolver{}; conn, err := grpc.Dial("dns:///service.example.com:50051", grpc.WithResolvers(resolver))
   ```
2. **** (90% 成功率)
   ```
   nslookup service.example.com; verify /etc/resolv.conf
   ```
3. **** (80% 成功率)
   ```
   conn, err := grpc.Dial("127.0.0.1:50051", grpc.WithInsecure())
   ```

## 无效尝试

- **Hardcoding an IP address instead of hostname.** — IP may change, causing future failures. (60% 失败率)
- **Retrying indefinitely without fixing DNS.** — DNS issue persists. (90% 失败率)
- **Modifying system DNS settings.** — May not be applicable in containerized environments. (50% 失败率)