ssl - AWS ELB IP 地址是 ELB 独有的吗？

Question

有谁知道带 SSL 的 AWS ELB 在幕后是如何工作的？在我的 ELB 域名上运行 nslookup，我得到 4 个唯一的 IP 地址。如果我的 ELB 启用了 SSL，AWS 是否可以与其他启用 SSL 的 ELB(不一定归我所有)共享这些相同的 IP？

据我了解，网络请求中的主机名位于 https 请求的加密网络请求中。如果是这种情况，AWS 是否必须为每个启用 SSL 的 ELB 提供唯一的 IP 地址，这些 IP 地址永远不会与其他任何人的 SSL ELB 实例共享？换句话说——AWS 是否为您请求的每个 SSL ELB 提供 4 个唯一的 IP 地址？

Answer 1

Does anyone know how AWS ELB with SSL work behind the scenes? [...] Put another way -- does AWS give 4 unique IP addresses for every SSL ELB you've requested?

Elastic Load Balancing (ELB) 本身采用可扩展架构，这意味着分配给您的 ELB 的唯一 IP 地址的数量实际上会根据容量需求和您的 ELB 各自的扩展事件而有所不同，请参阅扩展弹性负载均衡器 在 Best Practices in Evaluating Elastic Load Balancing 内(它提供了对 Elastic Load Balancing 服务的架构及其工作原理的非常详细的解释):

The controller will also monitor the load balancers and manage the capacity [...]. It increases capacity by utilizing either larger resources (resources with higher performance characteristics) or more individual resources. The Elastic Load Balancing service will update the Domain Name System (DNS) record of the load balancer when it scales so that the new resources have their respective IP addresses registered in DNS. The DNS record that is created includes a Time-to-Live (TTL) setting of 60 seconds,[...]. By default, Elastic Load Balancing will return multiple IP addresses when clients perform a DNS resolution, with the records being randomly ordered [...]. As the traffic profile changes, the controller service will scale the load balancers to handle more requests, scaling equally in all Availability Zones. [emphasis mine]

这在 DNS 解析部分有进一步的详细说明，包括负载测试 ELB 设置的重要提示:

When Elastic Load Balancing scales, it updates the DNS record with the new list of IP addresses. [...] It is critical that you factor this changing DNS record into your tests. If you do not ensure that DNS is re-resolved or use multiple test clients to simulate increased load, the test may continue to hit a single IP address when Elastic Load Balancing has actually allocated many more IP addresses. [emphasis mine]

整个主题在 Shlomo Swidler 的出色分析 The “Elastic” in “Elastic Load Balancing”: ELB Elasticity and How to Test it 中进行了更详细的探讨，同时也引用了前面提到的 AWS 的 Best Practices in Evaluating Elastic Load Balancing，基本上证实了他的分析，但缺少 Shlomo 提供的说明性逐步示例。