给关键站点加一层页面级容灾 A page-level failover layer for critical sites
只有整页导航请求会走这套逻辑，图片、脚本这类子资源不接管。功能只面向增强版和定制版开放。 Only full-page navigation requests go through this logic; sub-resources such as images and scripts are not taken over. The capability is available in the Enhanced and Custom editions only.
页面级容灾，覆盖范围明确Page-level failover, with a clear scope
给关键站点启用高可用规则后，系统会注入页面容灾逻辑。主地址不可达时，页面导航请求可以切到预设的备用地址；没有可用的备用地址时，还可以给访客显示离线页。Once HA rules are enabled for a critical site, the system injects page-failover logic. When the primary is unreachable, page-navigation requests can switch to a preset backup address, and when no backup is available it can show visitors the offline page instead.
只有整页导航请求会进入容灾逻辑；图片、脚本等子资源请求不会被接管。Only full-page navigation requests enter the logic; sub-resource requests like images and scripts are not taken over.
页面导航请求会先按正常流程访问主地址。主地址响应成功时，响应直接返回，不触发跳转。A navigation first hits the primary as usual; when the primary responds successfully, that response is returned directly, with no redirect.
主地址请求失败后，系统会以 no-cors 方式对备用地址进行轻量探测，超时时间约为 2.5 秒。只有探测确认备用地址可访问后，才会通过 302 跳转至该地址；跳转时保留原路径、查询参数和锚点，并设置粘滞状态。After the primary request fails, the system runs a lightweight no-cors probe of the backup with a timeout of about 2.5s. Only once the probe confirms the backup is reachable does it 302-redirect there, preserving the original path, query and hash and setting a sticky state.
如果备用地址探测也失败，系统将返回可配置的离线页，避免访客直接看到原始错误信息。If probing the backups also fails, the system returns a configurable offline page instead of exposing the raw error to visitors.
按需要选择授权版本和档位Choose the edition and tier you need
按节点数和授权站点数（以根域名 Zone 计）透明计费。选哪一档看实际部署规模，选哪个版本看您需要哪些高级功能与服务。Transparent pricing, based on licensed node count and licensed sites counted per root-domain Zone. The tier follows your deployment size; the edition follows which advanced capabilities and services you need.