Q81 — AWS ANS-C01 Ch.1

Question 81 of 100 | ← Chapter 1

A company has deployed a software-defined WAN (SD-WAN) solution to interconnect all of its offices. The company is migrating workloads to AWS and needs to extend its SD-WAN solution to support connectivity to these workloads.A network engineer plans to deploy AWS Transit Gateway Connect and two SD-WAN virtual appliances to provide this connectivity. According to Company policies, only a single SD-WAN virtual appliance can handle traffic from AWS workloads at a given time. How should the network engineer configure routing to meet these requirements?

• A. Add a static default route in the transit gateway route table to point to the secondary SD-WAN virtual appliance. Add routes that are more Specific to point to the primary SD-WAN virtual appliance.
• B. Configure the BGP community tag 7224:7300 on the primary SD-WAN virtual appliance for BGP routes toward the transit gateway.
• C. Configure the AS_PATH prepend attribute on the secondary SD-WAN virtual appliance for BGP routes toward the transit gateway. ✓
• D. Disable equal-cost multi-path (ECMP) routing on the transit gateway for Transit Gateway Connect.

Correct Answer: C. Configure the AS_PATH prepend attribute on the secondary SD-WAN virtual appliance for BGP routes toward the transit gateway.

Explanation

AWS Transit Gateway Connect与BGP路由属性配置。BGP选路策略中，AS_PATH长度影响路由优先级，较短的路径更优。在备用SD-WAN设备上设置AS_PATH prepend会人为增加路径长度，使主设备路由优先。AWS文档提到通过调整BGP属性控制路由选择，确保主备设备切换符合策略。选项C通过修改AS_PATH改变路径优先级，选项D禁用ECMP可能影响高可用性，选项B的社区标签不直接控制主备切换，选项A静态路由缺乏动态适应性。