How to Improve Inter-Data-Center Reliability with Direct Connect SiteLink?

ANS-C01 By islever Editorial Last updated

Short answer

D Enable the Direct Connect SiteLink feature on the existing transit VIFS that are attached to the existing Direct Connect gateway.

Question

A company has two on-premises data centers. The first data center is in the us-east-1 Region. The Second data canter is in the us-east-2 Region. Each data center connects to the closest AWS Direct Connect facility. The company uses Direct Connect connections, transit VIFs, and a single Direct Connect gateway to establish connectivity to VPCs in us-east-1 and us-east-2 from the company’s data centers. The company also has private connectivity from a telecommunications provider that connects the first data center to the second data center. Recently, there have been multiple connection disruptions to the private connectivity between the data centers. The company needs a solution to improve the reliability of the connection between the two data centers. Which solution will meet these requirements?
  1. Create a new Direct Connect gateway. Enable the Direct Connect SiteLink feature on the transit VIF. Share the CIDR blocks from the first data center and the second data center with each other.
  2. Create a new public VIF to both Regions. Enable the Direct Connect SiteLink feature on the new public VIF.
  3. Enable the Direct Connect SiteLink feature on the existing Direct Connect connections.
  4. Enable the Direct Connect SiteLink feature on the existing transit VIFS that are attached to the existing Direct Connect gateway. Correct Answer

Key Takeaways

The question tests whether you know that SiteLink is enabled on transit VIFs attached to an existing Direct Connect gateway, not on the physical connections or new VIFs.

AWS Direct Connect SiteLink allows data transfer between Direct Connect locations over AWS's global network, eliminating reliance on private telecom links. The community consensus is that enabling SiteLink on existing transit VIFs attached to a Direct Connect gateway is the correct, minimal-change solution for inter-DC reliability.

Common mistake: Choosing A (creating a new Direct Connect gateway) or C (enabling SiteLink on the Direct Connect connections themselves) are common mistakes; they involve unnecessary changes or the wrong configuration point, whereas the correct approach uses the existing transit VIFs.

Expert Analysis

Why the Answer Is Correct

Option D is correct because Direct Connect SiteLink is designed to provide reliable connectivity between two Direct Connect locations using the AWS global network, bypassing third-party telecom links. By enabling SiteLink on the existing transit VIFs that are attached to the same Direct Connect gateway, the two data centers can communicate directly over AWS's backbone without modifying the existing architecture. As comment [1] notes, this avoids reliance on private connectivity between the on-premises data centers. Comment [2] adds that SiteLink establishes a site-to-site link, ensuring high availability even if one private connection fails. This minimizes changes and complexity, making it the best solution.

Why the Other Options Are Wrong

Option A is wrong because it proposes creating a new Direct Connect gateway and sharing CIDR blocks, which is unnecessary and adds complexity. The existing Direct Connect gateway already provides the required connectivity, and SiteLink works with the existing gateway. Option B is wrong because public VIFs are used for public AWS services, not for private data center interconnectivity, and SiteLink is not available on public VIFs. Option C is wrong because SiteLink is a feature of transit VIFs, not of the physical Direct Connect connections themselves. Enabling it on the connections would have no effect. Only option D correctly targets the transit VIFs attached to the existing Direct Connect gateway.

Community Comment Notes

Comment [4] provides the official AWS blog reference, which confirms the correct implementation. Comment [1] and [2] both explain the functional benefit of SiteLink, emphasizing that it uses AWS's network to replace the unreliable private link. Comment [3] highlights the advantage of minimizing changes to the existing setup. All commenters agree on option D, with 100% of votes for D, making it a straightforward consensus answer.

Official Reference

These links open the official vendor documentation in a new tab.

Exam Strategy

When you see Direct Connect SiteLink, remember that it is enabled on transit VIFs attached to a Direct Connect gateway, not on connections or public VIFs. Check whether the gateway already exists; if it does, avoid selecting options that create new gateways or VIFs—look for the minimal change that leverages the existing infrastructure.

Community Votes

D
100%

100% of anonymous learners picked answer D. Votes are pick records left by other test-takers — they are not the verified answer.

Discussion 5 contributions

Compiled from public community threads and reader submissions, lightly edited for clarity. Handles and vote tallies are shown as recorded, and comments reflect the views of individual contributors.

From public community threads 5

  1. Cacheirez 👍 2 Answered D
    Direct Connect SiteLink allows data transfer between two Direct Connect locations over the AWS global network, bypassing the need for private connectivity between on-premises data centers. By enabling SiteLink on the existing transit VIFs that are attached to the Direct Connect gateway, you can leverage AWS's backbone network to facilitate communication between the two data centers without relying on potentially unreliable private connectivity.
  2. AzureDP900 👍 1 Answered D
    D is right. By enabling SiteLink on the existing transit VIFS, we can establish a site-to-site link between the two data centers, which will allow traffic to be routed through both connections and ensure high availability in case of a connection disruption. This solution meets the requirements
  3. woorkim 👍 1 Answered D
    Option D is the best solution because it enables reliable and direct communication between the two data centers using the existing transit VIFs and Direct Connect infrastructure. This approach minimizes changes, reduces complexity, and improves the reliability of the connection.
  4. jhon648274 👍 1
    D is correct https://aws.amazon.com/blogs/networking-and-content-delivery/introducing-aws-direct-connect-sitelink/
  5. koukiman0514 👍 2 Answered D
    this is D

Reader comments & corrections

No reader corrections yet — spotted an error or have a note? Share it below.

Log in to comment, report an error, or add a note about this question.

Global Accelerator with private ALB: restrict access to accelerator IPs

S-grade

How to make one AWS Direct Connect connection primary and the other failover-only?

S-grade

How to Copy On-Premises Application Logs to Amazon S3 Over AWS Direct Connect?

S-grade

Why Does VPC Traffic Mirroring Randomly Drop Traffic?

S-grade

Practice All ANS-C01 Questions

Access 137 questions with complete answers and detailed explanations.

View Full ANS-C01 Practice Test →

← Back to ANS-C01 Study Guide