Lecture 192: Hybrid Connectivity
- 课程：[NEW] AWS Certified Advanced Networking Specialty 2026
- 视频时长：03:23
- 来源：Udemy Lecture 28556011
- Slide 数量：5
- 画面切换：01:05、01:39、02:05、03:03
扫描说明
逐条读取了 Udemy 页面中的 80 条英文 Transcript cue，并按时间轴扫描全长约 03:23 的视频。依据 On-premises Hybrid Target、Peered VPC Target、Internet-facing IPv4、Dualstack DNS/后端协议、Internal ELB 划分为 5 个小节。截图均在 Transcript 侧栏关闭、播放器控件隐藏后复核，统一为 1364×770。
Transcript 来自 Udemy 页面自带的英文自动字幕，没有使用 ASR。下面保留页面原文，包括其中的语法或识别错误。
1. 通过 VPN 或 Direct Connect 负载均衡到本地服务器
时间范围：00:00–01:05
总结 / Summary
中文
ALB 可以同时服务 VPC 内的 EC2 Target 与 Corporate Data Center 的 On-premises Server。前提是先用 Site-to-Site VPN 或 Direct Connect 建立私网连通性与正确路由；随后创建 IP 类型 Target Group，以本地服务器的 Private IP 注册。ALB 必须能到达这些地址并完成 Health Check，才会发送流量。
English
An ALB can serve both EC2 targets in its VPC and on-premises servers in a corporate data center. First establish private connectivity and routing through a site-to-site VPN or Direct Connect. Then create an IP-type target group and register the servers by private IP. The ALB must reach those addresses and pass health checks before sending traffic.
Transcript
00:00 Okay, so just a few architectures
00:02 we need to see
00:03 to really make sure we understand correctly the balancing,
00:05 because the exam will most likely ask you about
00:08 hybrid scenarios or DPC pairing scenarios.
00:12 And so you need to understand
00:12 how load balancing works in this case. So.
00:14 Let's say we have a very simple example right now,
00:16 we have a VPC and ALB and it's redacting into a target group
00:20 made of EC2 instances.
00:22 Now we also want to do some load balancing
00:24 across a target group made of on-premises servers
00:27 in our corporate data center.
00:29 So to achieve that, what we need to do is to establish a VPN
00:32 or a direct connect connection to connect our VPC
00:36 into our corporate data center.
00:38 Once that connection is established
00:39 and there is network connectivity between our VPC,
00:42 and our data center.
00:43 And therefore,
00:44 what we can do is that we can start creating a target group
00:46 and that target group has to be using private IPs.
00:50 So we would just do private IPs within a private group.
00:52 And obviously the ALB using this private IP
00:55 has the connectivity to help check our on-premises server.
00:59 Therefore it will work and the traffic can be sent
01:01 from the ALB directly to our on-premises servers.
2. 通过 VPC Peering 访问另一 VPC 的 Private IP Target
时间范围：01:05–01:39
总结 / Summary
中文
若 EC2 位于另一个 VPC，甚至另一个 AWS Account，可先建立 VPC Peering，使两侧 Private Traffic 可路由。ALB 所在 VPC A 再创建 IP 类型 Target Group，以 VPC B 中 Instance 的 Private IP 注册。Peering 与 Route Table/Security Control 必须允许 Health Check 和业务端口双向通信。
English
If EC2 instances live in another VPC, even in another AWS account, establish VPC peering so private traffic is routable. The ALB in VPC A then uses an IP-type target group containing private IPs from VPC B. Peering, route tables, and security controls must allow both health-check and application-port communication.
Transcript
01:05 This is very similar with peered VPCs.
01:07 So, say we have an ALB and VPC A,
01:09 and we have other EC2 instances in another VPC.
01:13 Maybe it's another VPC in another account, who knows.
01:15 The idea is that you would also want to
01:17 send traffic from the ALB to this other VPC
01:21 and to do so, well we first need to establish
01:23 a VPC peering connection.
01:24 Which will make sure that private traffic
01:27 can flow between the two VPCs.
01:29 And therefore we can define a second target group,
01:31 again using private IPs to make sure the ALB sends traffic
01:36 all the way to the target EC2 instances.
3. Internet-facing ELB 位于 Public Subnet，但后端使用 Private IP
时间范围：01:39–02:05
总结 / Summary
中文
Internet-facing Load Balancer 在多个 Public Subnet 中接收外部客户端连接，并通常把流量发往 Private Subnet 的 EC2。即使前端对公网开放，ELB 也会终止连接并用 Private IP 连接 Backend，因此 Instance 看到的是 ELB 私网来源，而不是直接暴露公网入口。
English
An internet-facing load balancer receives external client connections in public subnets across multiple AZs and normally forwards to EC2 in private subnets. Even though the frontend is public, the ELB terminates the connection and reaches backends through private IPs, so instances see a private ELB source rather than a direct public ingress.
Transcript
01:39 Okay finally, just a distinction between internet-facing
01:42 and internal load balancers.
01:43 So, internet-facing load balancers look like this,
01:46 where your ALB sits in a public subnet. Okay?
01:49 And then sends traffic, usually to EC2 instances
01:53 in a private subnet, and is using IPv4 only.
01:56 So the private, the EC2 instances see traffic originating
02:00 from private IP addresses only
02:01 because your ALB is terminating the connection.
4. Dualstack 让客户端用 IPv4/IPv6，后端仍走 IPv4
时间范围：02:05–03:03
总结 / Summary
中文
Internet-facing ELB 可选 IPv4-only 或 Dualstack。课程展示常规 name… DNS、ipv6.name… 与 dualstack.name…：Dualstack 会根据客户端网络能力返回 IPv6 或 IPv4。无论客户端前端使用 IPv6 还是 IPv4，ELB 终止连接后到 EC2 Backend 仍使用 Private IPv4。
English
An internet-facing ELB can be IPv4-only or dualstack. The course shows regular name…, ipv6.name…, and dualstack.name… DNS forms; dualstack returns IPv6 or IPv4 according to client network support. Regardless of whether the client frontend uses IPv6 or IPv4, the ELB terminates the connection and reaches EC2 backends with private IPv4.
Transcript
02:05 But what's going to happen
02:06 is that you can also enable dual stack.
02:10 So the idea is that right now it's IPv4,
02:12 but you can also have IPv4 and IPv6
02:15 for the clients to connect to your ALB.
02:18 The idea is that now you will have different domain names.
02:21 So you'll have, name,
02:22 the first name is just your regular IPv4 domain name.
02:26 The IPv6 dot the same name as your IPv6 DNS endpoint.
02:31 So if you do a DNS query against that name,
02:33 you will get an IPv6 as a result,
02:36 or if you want it to just either be redirected to IPv6
02:39 or IPv4 based on your compatibility of connection.
02:42 You would use a dual stack end point,
02:44 and dual stack is the dual stack dot the name.
02:47 And this will give you either the IPv6,
02:49 if it's supported by your network,
02:50 or the IPv4.
02:52 But regardless if using an IPv6 as an endpoint,
02:55 the traffic that will be sent
02:56 into your EC2 instances will be IPv4.
02:58 That's because your ELB does terminate your connections.
5. Internal ELB 仅在私网内使用 IPv4
时间范围：03:03–03:23
总结 / Summary
中文
Internal ELB 用于 AWS 内部的 Private Traffic，课程指出它只使用 IPv4；客户端与 Backend 都通过 Private IP 交互，流量保留在 AWS Account/VPC 可达网络中。其 DNS Name 以 internal- 开头，可作为辨识 Internet-facing 与 Internal Load Balancer 的线索。
English
An internal ELB serves private traffic inside AWS, and the course states that it operates in IPv4 mode. Clients and backends communicate through private IPs within the account and reachable VPC network. Its DNS name begins with internal-, which helps distinguish it from an internet-facing load balancer.
Transcript
03:03 Now, if you're using an internal ELB,
03:05 you can only use it in IPv4 mode
03:07 and all the traffic will remain within your AWS accounts,
03:10 using private IP addresses
03:12 and then the DNS name of your balancer
03:15 should start by internal dash
03:17 and then the name of your load balancer. Okay?
03:19 So that's it for this lecture. I hope you liked it.
03:21 And I will see you in the next lecture.
整讲总结 / Overall Summary
中文
ALB 可通过 IP Target Group 把流量发往经 VPN/Direct Connect 可达的 On-premises Server，或经 VPC Peering 可达的另一 VPC Private IP。Internet-facing ELB 前端可 IPv4 或 Dualstack，但后端始终用 Private IPv4；Internal ELB 保持私网 IPv4，DNS 名以 internal- 开头。
English
ALB can route through an IP target group to on-premises servers reachable over VPN/Direct Connect or to private IPs in a peered VPC. An internet-facing ELB frontend can be IPv4 or dualstack, while the backend remains private IPv4. An internal ELB stays on private IPv4 and uses an internal- prefixed DNS name.
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