Why DIA at every SD-WAN site reduces cloud latency and MPLS load

300-420 By islever Editorial Last updated

Describe Cisco SD-WAN design considerations (control plane design, overlay design, LAN design, high availability, redundancy, scalability, security design, QoS and multicast over SD-WAN fabric) Describe WAN connectivity options for on-premises, hybrid, and cloud solutions

Short answer

AE Local Internet breakout at each site cuts latency to public-cloud applications and offloads traffic from MPLS circuits.

Question

What are two benefits of designing an SD-WAN network fabric with direct Internet access implemented at every site? (Choose two.)
  1. It decreases latency to applications hosted by public cloud service provider. Correct Answer
  2. It decreases latency on Internet circuits.
  3. It increases the speed of delivery of site deployments through zero-touch provisioning.
  4. It increases the total available bandwidth on Internet circuits.
  5. It alleviates network traffic on MPLS circuits. Correct Answer

Key Takeaways

The exam tests whether you can separate benefits caused by local Internet breakout (A, E) from general SD-WAN benefits like ZTP (C) that are unrelated to the design choice in the question.

This 300-420 question tests the benefits of direct Internet access (DIA) at every SD-WAN site. The correct pair is A and E: lower latency to public cloud applications and reduced traffic on MPLS circuits.

Common mistake: Option C is the most plausible wrong pick: zero-touch provisioning genuinely speeds site deployment, but it is a function of SD-WAN onboarding via vManage and is unchanged by whether a site uses DIA.

Expert Analysis

The allure of option C

Option C is the trap in this question, and it is an appealing one: zero-touch provisioning is unambiguously a headline benefit of Cisco SD-WAN, and the official design material repeatedly ties ZTP to rapid branch rollouts. A learner who reads "speed of delivery of site deployments" recognizes the vocabulary instantly and selects C alongside A. The comment stream shows exactly this pull, with several voters pairing A with C on the reasoning that "ZTP is a major benefit."

Where C stops being correct

The question does not ask about SD-WAN onboarding in general; it asks about the benefits of designing the fabric with direct Internet access implemented at every site. ZTP is triggered by the vEdge/cEdge first boot reaching vManage for image and configuration download — it is a property of SD-WAN provisioning itself, and it occurs regardless of whether a given site breaks out locally to the Internet or backhauls to a hub. Adding a local Internet transport does nothing to shorten the provisioning workflow. So C satisfies the general topic but not the specific design feature under test.

The defensible pair: A and E

Option A is directly supported: with DIA, branch traffic to public cloud and SaaS exits locally instead of being tunneled to a central site, so latency to cloud-hosted applications drops. Option E follows from the same mechanics: web, video and SaaS flows that would previously consume expensive MPLS capacity are offloaded to the local Internet circuit, preserving MPLS for data-center traffic. B and D are wrong because DIA does not make an existing Internet circuit faster or add bandwidth — it changes where traffic is sent, not the link's throughput.

Official Reference

https://www.cisco.com/c/dam/en/us/td/docs/solutions/CVD/SDWAN/sdwan-dia-deploy-2020aug.pdf

This link opens the official vendor documentation in a new tab.

Exam Strategy

Anchor every option to the exact design feature named in the stem — here, DIA at every site — and discard choices that describe a generic SD-WAN property rather than a consequence of local Internet breakout. When a benefit is true of SD-WAN in general but indifferent to the stated feature, it is a distractor; verify by asking whether the option would change if DIA were removed.

Frequently Asked Questions

Why is zero-touch provisioning not a benefit of DIA at every site?

ZTP is triggered when a device first boots and contacts vManage for image and configuration, a workflow that runs no matter which transport the site uses. Adding a local Internet breakout does not shorten that provisioning sequence, so it is not a DIA-specific benefit.

Does direct Internet access increase available bandwidth on Internet circuits?

No. DIA changes where branch traffic is sent, not the capacity of the link. Total circuit throughput stays the same; only the share of traffic carried by MPLS decreases as Internet and SaaS flows exit locally.

How does DIA reduce latency to public cloud applications?

Without DIA, branch traffic to SaaS or public cloud is tunneled to a central hub and then out to the Internet, adding hops and round-trip time. Local breakout sends the traffic straight from the site's edge to the Internet, cutting that path.

More 300-420 FAQ →

Community Votes

A
50%
E
25%
C
21%
D
4%

50% of anonymous learners picked answer A. Votes are pick records left by other test-takers — they are not the verified answer.

Discussion 18 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 18

  1. ccnproute1 👍 5
    I agree with A and E. From OCG states "With DIA, Internet-bound traffic or public cloud traffic from the branch is routed directly to the Internet, avoiding the latency involved in tunneling Internet-bound traffic to a central site." This corresponds to answer A. And then "Benefits of using DIA include reduced bandwidth consumption, latency, and costs (thanks to offloading Internet traffic from the private WAN circuit)." Meaning that basically offloads internet traffic from the MPLS (private WAN) and routed directly to DIA. SD-WAN cannot increase by itself, only ISP can do that.
  2. atiWok 👍 4
    Definetly AE
  3. Seb82 👍 3
    Nowhere in the question it is mentioned that the sites have also an MPLS circuit, so, having DIA at each site cannot alleviate traffic from some non-existent MPLS circuits, but it can be used to speed up the deployment via ZTP
  4. XalaGyan 👍 3
    It is actually A and D. you have more resources available for cloud apps and in total you have more wan capacity for system to use
  5. Swiz005 👍 3
    I go with AE - These are advantages of SD-WAN
Show 13 more comments
  1. GustavoF 👍 3
    I go with A & E.
  2. zlimvos 👍 2
    I agree with A and E by instinct alone. DIA is configured on the edge router way after you get access to it, i don't think ZTP is applicable.
  3. foxiemulder 👍 2
    it's a A and C. The question doesn't even mention MPLS, so E doesn't make sense. ZTP is a major benefit.
  4. salmarin 👍 2
    the only two that make sense to me A and C.
  5. Swiz005 👍 2
    How is this not AC?
  6. adcym 👍 2
    A,E is answer.
  7. G_Singh12 👍 1
    Backhauling massive amounts of web, video, and SaaS traffic severely congests expensive, private MPLS circuits. By offloading all standard internet and public cloud traffic directly to local internet breakouts, you preserve precious MPLS bandwidth purely for critical corporate data center traffic.
  8. mladjo89 👍 1
    According to the following link I would say A and E are correct answers: https://www.cisco.com/c/dam/en/us/td/docs/solutions/CVD/SDWAN/sdwan-dia-deploy-2020aug.pdf
  9. akbntc 👍 1
    A & C. Option E is for deployment in MPLS circuits. The solution in asking for deploying SDWAN on DIA circuits.
  10. Tjemz 👍 1
    agree on A en D https://www.cisco.com/c/dam/en/us/td/docs/solutions/CVD/SDWAN/sdwan-dia-deploy-2020aug.pdf
  11. akbntc 👍 1
    A is correct, but why E? The solution is using DIA, not MPLS.
  12. night_wolf_in 👍 1
    No mention of MPLS circuits in the question.
  13. mladjo89 👍 1
    Answer is on the page 6.

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.

POV Report Builds the Customer Platform During Discovery

S-grade

VPLS design for sites sharing one IP subnet

S-grade

Inter-VN Communication in Cisco SD-WAN Architecture

S-grade

Advertising a Default Route from Core to Aggregation to Hide Instability

S-grade

Practice All 300-420 Questions

Access 150 questions with complete answers and detailed explanations.

View Full 300-420 Practice Test →

← Back to 300-420 Study Guide