25 SD-WAN Interview Questions (With Some Sample Answers)

Updated 23 March 2023

During interviews, network engineers and administrators typically encounter a variety of questions about networking models and technologies. SD-WAN, or software-defined wide area network, is a relatively new technology to improve the performance of traditional WAN systems. Reviewing questions related to SD-WAN can help you compose well-structured responses and impress an interviewer with your knowledge. In this article, we share 25 SD-WAN interview questions with sample answers to help you prepare for your next interview.

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10 SD-WAN Interview Questions With Example Answers

Network engineers and analysts can benefit from reviewing various SD-WAN interview questions when applying for jobs. Knowing about this technology and its operations can highlight your expertise and show the interviewer that you have the required skills and knowledge for the role. Here are sample questions and answers relating to SD-WAN:

1. What is SD-WAN?

This basic question checks whether you understand the fundamental concepts of SD-WAN. It also establishes your ability to explain the concepts easily. In your response, define SD-WAN, discuss its utility and explain why it is gaining popularity.

Example: SD-WAN is a type of wide area network that uses software-defined technology to manage heavy network connectivity and traffic in a flexible, cost-effective and secure manner. SD-WAN helps increase the performance of a traditional WAN while simplifying its management. As a result, SD-WAN allows businesses to design high-performance network infrastructure without incurring high costs.

Related: Top 10 VLAN Interview Questions (With Example Answers)

2. How does SD-WAN work?

Knowing how SD-WAN enhances the performance of traditional WAN networks can demonstrate that you have a thorough understanding of the technology. Describe the basic functioning of SD-WAN technology and how it achieves its intended goal. Use simple terms when explaining your answer so it is easily understandable.

Example: SD-WAN implements a central control function across all devices to direct traffic securely through the WAN. By simplifying the traditional WAN architecture through an overlay that virtualises the network, SD-WAN steers traffic directly to required SaaS or IaaS providers. Monitoring the performance of all devices and WAN connections ensures high speeds and reduces network inefficiencies.

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3. What are the business benefits of SD-WAN?

By asking you this question, the interviewer is assessing whether you have the required business acumen related to SD-WAN and can interact with clients. In your answer, discuss a few significant benefits of this technology for different business aspects.

Example: Businesses with high networking requirements can benefit from SD-WAN, as it can scale their network systems without expensive investments. SD-WAN can improve the user and application experience by dynamically routing traffic. It can also enhance the security of networks through end-to-end segmentation, optimise cloud connectivity and simplify network management and operations.

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4. Explain the components of an SD-WAN architecture

Network engineers and administrators often set up, maintain and migrate to SD-WAN architectures. Knowing its components shows that you have the required knowledge and expertise. When responding, name all the elements and briefly explain their functions.

Example: An SD-WAN architecture consists of the SD-WAN Edge, which is the physical or virtual network function and SD-WAN Gateway that provides access. Then there is the SD-WAN Orchestrator, a web management tool to operate the network, and the SD-WAN Controller, which makes forwarding decisions for application flows. In addition, different providers may offer customised management tools or consoles to simplify operating and configuring the network.

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5. Discuss the security capabilities of SD-WAN

Network security is crucial when evaluating any tool or technology to improve performance. With this question, the interviewer is assessing whether you are aware of the security features of SD-WAN and can explain them to potential clients. In your response, list the different safety features SD-WAN vendors offer.

Example: SD-WAN typically uses Internet Protocol Security, or IPsec, next-generation firewalls, segmentation of traffic and VPN tunnels. Engineers and administrators can manage these security features easily through the solution. Depending on the vendor, additional built-in security features, such as application-aware firewalls, intrusion prevention, URL filtering and DNS layer enforcement, may also be available.

Related: 7 Frequently Asked CCNA Interview Questions (With Answers)

6. What are the benefits of network segmentation?

Network segmentation creates several segments or subnets in a network. This enables each subnet to operate independently. When answering this question, list the advantages of network segmentation and explain how it can help a business.

Example: Network segmentation can provide higher security by separating different application segments. This can also enable businesses to create different segments for different users, keeping their data and accessibility separate. Segmentation also helps implement centralised policies to control access to information and networks.

7. What is a virtual private network?

SD-WAN creates virtual private networks for segmentation. The interviewer may ask this question to assess your functional knowledge of SD-WAN. Define the purpose of virtual private networks in SD-WAN and discuss some of their characteristics and functions in your answer.

Example: In SD-WAN overlays, a virtual private network, or VPN, creates segmentation in the network overlay through virtual routing and forwarding or VRF. VPNs in SD-WAN are unique and have distinct forwarding tables. An interface or sub-interface configured under one VPN cannot be an element of different VPNs. Labels help identify VPNs and determine the VPN to which packets belong.

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8. What is vManage?

Cisco is a leading SD-WAN solution provider. If you have operational knowledge of this system, highlight your practical knowledge and experience. In your answer, explain the uses and features of vManage.

Example: vManage is a cloud-hosted Graphic User Interface management console to operate Cisco's SD-WAN solution. This centralised tool helps manage the entire network and its security. In addition, this tool can help network administrators easily automate the configuration, management and operation of the whole solution.

9. What is TLOC, and what purpose does it serve?

As in the previous question, this is about Cisco's SD-WAN solutions. Knowing the role of The Transport Locator (TLOC) in Cisco's SD-WAN network can show your expertise and practical abilities. Define TLOC and discuss its function and properties in your answer.

Example: TLOC is the static identifier in Cisco vEdge devices and acts as the point of connection between the device and a WAN transport. TLOC works like a routing locator, and it routes separate transport locations. TLOC has three elements: the IP address, colour and encapsulation type.

Related: What Does A Network Engineer Do? (Salary, Skills And Career)

10. How does artificial intelligence improve the capabilities of SD-WAN?

Many SD-WAN solutions use artificial intelligence technologies to optimise the network's performance. Knowing the application of artificial intelligence tools in SD-WAN can impress the hiring manager by demonstrating an in-depth understanding of the technology. In your response, briefly describe how SD-WAN systems use artificial intelligence tools and mention the benefits.

Example: The use of artificial intelligence, or AI, in SD-WAN can further improve its performance, security and application experience. AI can provide smart application-aware routing, and through continuous learning and self-monitoring, AI-driven SD-WAN networks can adapt to changes automatically. This can help reduce network congestion, minimise operational burden and automate troubleshooting.

Related: How To Write An Effective Network Administrator Resume

15 More SD-WAN Interview Questions

Here are some more interview questions you can expect in your interview:

  1. What is the DevNet Ecosystem Exchange?

  2. What is a Site ID?

  3. Define TPM and explain its functions.

  4. Does the deployment of SD-WAN restrict hardware at branch sites?

  5. What industries can benefit the most from using SD-WAN solutions?

  6. What are the latest trends and innovations in the SD-WAN industry?

  7. What is a Domain ID?

  8. List the differences between centralised and localised policies.

  9. What is a device template, and how do you create one?

  10. Explain how zero-trust security works in SD-WAN.

  11. What is ZTP, and what are its requirements?

  12. Define Overlay Management Protocols and list their types.

  13. What is DPI, and what is its traffic symmetry?

  14. What are controller connections?

  15. What are some vendors offering SD-WAN solutions?

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