Question 1,080 of 1,621
Global Accelerator Traffic Routing: Endpoint Weight Issue
A media company streams live video to viewers worldwide. The application runs on EC2 instances behind an Application Load Balancer in two AWS regions, us-east-1 and eu-west-1. The company uses Amazon CloudFront as a CDN with origins pointing to both regional ALBs. The network team recently deployed AWS Global Accelerator to improve performance by directing traffic to the nearest healthy endpoint. However, after enabling Global Accelerator, viewers in Europe report buffering issues, while viewers in the US have no issues. The team has verified that the Global Accelerator endpoints are healthy and the ALBs are functioning correctly. The application uses a custom domain name. The DNS is managed by Route 53. What is the most likely cause of the buffering issues for European viewers?
Quick Answer
The answer is a Global Accelerator endpoint weight misconfiguration, which causes European traffic to be routed to the us-east-1 endpoint instead of the closer eu-west-1 endpoint. This occurs because Global Accelerator uses anycast static IPs and traffic distribution is governed by endpoint weights; if the eu-west-1 endpoint is assigned a lower weight or is misconfigured, the accelerator may send a disproportionate share of European requests to the higher-weighted us-east-1 endpoint, introducing unnecessary latency and buffering. On the AWS Certified Advanced Networking Specialty ANS-C01 exam, this scenario tests your understanding of how Global Accelerator’s traffic dials and endpoint weights interact with geographic proximity—a common trap is assuming health checks alone guarantee optimal routing, when weight misconfiguration can override latency-based steering. Remember the mnemonic: “Weight wins over proximity”—always verify that endpoint weights are balanced to match regional capacity and user distribution.
Answer choices
Why each option matters
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Global Accelerator is directing European traffic to the us-east-1 endpoint due to endpoint weight misconfiguration.
Global Accelerator provides static IP addresses that are anycast from edge locations. If viewers' DNS queries resolve to the Global Accelerator DNS name, they get IPs that may route to the us-east-1 endpoint if the eu-west-1 endpoint is not properly configured or weighted, causing high latency. The most common issue is that the DNS resolution for the custom domain points to Global Accelerator, but the routing within Global Accelerator may not be directing European traffic to the eu-west-1 endpoint if the endpoint weights are misconfigured or if one endpoint is unhealthy. Option B is wrong because CloudFront origins are separate; Global Accelerator is used instead of CloudFront? Actually, they use both, but the issue is after enabling Global Accelerator. Option C is wrong because CloudFront would not cause issues when Global Accelerator is used. Option D is wrong because the application is not on-premises.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
Global Accelerator is directing European traffic to the us-east-1 endpoint due to endpoint weight misconfiguration.
Why this is correct
If weights are not set to distribute traffic, all traffic may go to one region.
- ✗
The Route 53 DNS record is not pointing to Global Accelerator but to CloudFront, bypassing Global Accelerator.
Why it's wrong here
If bypassed, Global Accelerator would not cause issues.
- ✗
CloudFront is caching content from the us-east-1 origin only, causing high latency for European viewers.
Why it's wrong here
CloudFront would cache from the nearest origin if configured with both origins.
- ✗
The eu-west-1 ALB is not configured to accept traffic from Global Accelerator IPs.
Why it's wrong here
Global Accelerator uses its own IPs, but ALB security groups should allow them; however, this would cause connection failures, not just buffering.
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Same concept, more angles
1 more way this is tested on ANS-C01
These questions test the same concept from different angles. Work through them to make sure you can recognise it however the exam phrases it.
Variation 1. A network engineer is designing a multi-region application that requires low-latency traffic between EC2 instances in two different AWS Regions. The engineer needs to ensure that traffic between the instances uses the AWS global network and not the public internet. Which AWS service should be used?
hard- A.AWS Direct Connect
- B.AWS Global Accelerator
- C.AWS Transit Gateway
- ✓ D.VPC Peering
Why D: (VPC Peering). Inter-region VPC peering connects VPCs in different regions using the AWS global network backbone, providing low-latency and private connectivity between EC2 instances. Option A (AWS Direct Connect) is used for on-premises to AWS connectivity, not between instances. Option B (AWS Global Accelerator) optimizes internet-facing traffic and adds unnecessary hops for internal traffic. Option C (AWS Transit Gateway) supports inter-region transit but requires additional configuration and is not the simplest solution for direct instance-to-instance connectivity.
Last reviewed: Jun 20, 2026
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