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SD-WAN Interview Questions & Answers

SD-WAN Interview Questions
By Emma Parrish

If you’re looking for SD-WAN interview questions, then read on my friend, I’ve got you covered! If SD-WAN is on your radar, it’s crucial to come prepared, knowing that your understanding of Software-Defined Wide Area Networking could set you apart in a competitive job market.

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SD-WAN is not just a buzzword but a transformative technology reshaping how businesses connect multiple locations securely and efficiently.

In this article, we will explore the most commonly asked interview questions on SD-WAN, providing you with the insights needed to demonstrate your expertise and experience effectively. Let’s navigate through these questions together, ensuring you step into your interview with confidence and a deep understanding of SD-WAN.

What Does SD-WAN Stand For?:

SD-WAN, or Software-Defined Wide Area Network, represents a pivotal shift in how businesses approach their network infrastructure. With an increasing number of organizations operating across multiple locations, the demand for a more flexible, secure, and efficient way to manage network connections has surged. SD-WAN offers a solution by transporting data across various sites, leveraging software to control and optimize the flow of information. Demonstrating your grasp of SD-WAN’s core principles and its application in real-world scenarios is vital for acing your interview. For a deeper understanding, consider exploring resources from authoritative sites such as Cisco’s SD-WAN overview [[Cisco, “https://www.cisco.com/site/uk/en/solutions/networking/sdwan/index.html”]] or VMware’s SD-WAN insights [[VMware blog, “https://blogs.vmware.com/management/2020/06/enhanced-sd-wan-insights-with-vrealize-network-insight.html”]] to enrich your knowledge base.

Top 20 SD-WAN Interview Questions and Answers

Below I’ve put together a list of the top 20 most commonly asked SD-WAN interview questions, along with an example answer that you can use as a framework for your own answers.

Q1. What is SD-WAN? How does SD-WAN work?

The interviewer wants to see if you can clearly and succinctly define SD-WAN, indicating your foundational knowledge of the subject. Beyond just a textbook definition, they’re interested in your understanding of what SD-WAN means in the context of modern networking. You should be able to describe the main components of SD-WAN, such as the SD-WAN edge, orchestrator, and controller.An explanation of how SD-WAN uses software to manage and optimize traffic across WAN links, including how it differs from traditional WAN technology.

Example‘Software-defined Wide Area Network (SD-WAN) is a type of technology that uses software to manage the connections between local networks and wide area networks (WANs). It provides an overlay network on top of the existing physical WAN infrastructure, allowing organizations to manage and control their WAN connections to optimize performance easily. By using centralized control, SD-WAN can dynamically route traffic across multiple WAN links based on criteria such as cost, latency, or packet loss to ensure optimal performance.’

Q2. What are the benefits of using SD-WAN?

The interviewer will look for you to articulate the key benefits of SD-WAN, such as improved bandwidth efficiency, higher security, cost savings, and increased network agility. Demonstrating knowledge of practical applications and scenarios where SD-WAN provides solutions to common networking challenges.

Example: ‘SD-WAN offers several advantages over traditional WAN solutions. For example, increased bandwidth and scalability, improved performance, enhanced security, and lower costs. Besides that, it also provides greater visibility into the network and makes it easier to manage and troubleshoot.’

Q3. What is an overlay network? How does it relate to SD-WAN?

Example: ‘An overlay network is a virtual network that sits on top of an existing physical network. It is used to provide additional features or services without having to reconfigure the physical network infrastructure. In the context of SD-WAN, an overlay network provides a secure and reliable connection between different locations, allowing them to be managed from a central point.’

Q4. Give me an example of what challenges SD-WAN can help solve.

Example: ‘SD-WAN can help organizations overcome several challenges, including poor network performance due to latency and packet loss, lack of visibility into the network status, difficulty managing multiple locations, and the need to maximize cost savings by leveraging cloud applications and services.’

Q5. What is the difference between SD-WAN and traditional WAN?

Example: ‘The main difference between SD-WAN and traditional WAN is that SD-WAN uses software-defined networking (SDN) to create virtual networks that are managed centrally. Traditional WAN solutions require physical connections between sites and manual configuration. SD-WAN also offers improved performance, enhanced security, and lower costs than traditional WANs.’

Q6. How does SD-WAN provide increased bandwidth?

Example: ‘SD-WAN provides increased bandwidth because SD-WAN uses multiple paths to connect sites and branches, allowing for more efficient utilization of available bandwidth. This allows for more traffic to be sent over the same connection, resulting in increased bandwidth and improved performance.’

Q7. What is traffic engineering, and how does it help with SD-WAN?

Example: ‘Traffic engineering is the process of analyzing, controlling, and optimizing traffic flow across a network. In the context of SD-WAN, traffic engineering helps ensure that data is routed through the most efficient paths, resulting in improved performance and reliability.’

Q8. What challenges have you faced while working with SD-WAN?

Example: ‘Working with SD-WAN can present a variety of challenges. One of the most significant challenges is ensuring the security of the network. As SD-WAN technology is relatively new, there is still a high risk of potential security vulnerabilities. To reduce this risk, organizations must ensure that their SD-WAN solution has been properly configured and is regularly monitored for any changes or issues. Furthermore, ensuring adequate bandwidth is another challenge when working with SD-WAN. This is because SD-WAN technology requires more bandwidth than traditional WAN solutions.

Organizations must ensure they have enough available bandwidth to support the required traffic. Finally, interoperability with existing systems can also be a challenge. Organizations must ensure that their SD-WAN solution is compatible with their existing systems and can seamlessly integrate. Dealing with these challenges can be difficult, but with careful planning and implementation, organizations can ensure that their SD-WAN solution is both secure and effective.’

Q9. How would you design an SD-WAN network?

Example: ‘Designing an SD-WAN network begins with understanding the network requirements, such as which locations need to be connected, what applications will be used, and the expected throughput. Once these requirements are established, the next step is to decide on the type of WAN technology to use. 

Once a WAN technology is chosen, the next step is to select the appropriate hardware and software. This includes choosing the right routers, switches, and firewalls for the particular application and company setup. Also, any specialized software or features needed to manage the SD-WAN network should be chosen.

The third step in designing an SD-WAN network is configuring the hardware and software. This includes, among others, setting up the WAN routers, switches, and firewalls. It may also include setting up Quality of Service policies, security protocols, and other network management settings.

Finally, once the hardware and software have been configured and tested, the SD-WAN network can be launched. This involves ensuring that all locations are properly connected, that data is flowing correctly, and that users can access the applications they need. Additionally, monitoring should be put in place to ensure that any issues are quickly identified and resolved.’

Q10. How would you troubleshoot an issue with an SD-WAN deployment?

Example: ‘To troubleshoot SD-WAN deployment issues, the first step is identifying the root cause. This can be done by gathering data from the network environment, such as logs, performance metrics, and configuration settings. Once the root cause of the issue is identified, it can be addressed by implementing corrective measures to resolve the issue.

The next step is to determine the scope of the problem. This involves understanding the issue’s impact on the SD-WAN environment and the extent of the problems that need to be resolved. It is essential to ensure that all elements of the SD-WAN solution are accounted for, such as routers, switches, firewalls, and other network devices. Once the scope of the problem is known, the next step is to develop a plan of action to address the issue. This may involve making changes to the network configuration, running diagnostic tests, and deploying patches or updates to the software. It is also important to ensure that the steps taken to resolve the issue do not have any unintended consequences.

Finally, it is important to monitor the SD-WAN environment to ensure that the changes made to address the issue are successful. This involves regularly checking the performance metrics, logs, and configuration settings to ensure that the issue has been successfully resolved. If the issue persists, additional corrective measures may need to be taken.’

Related: Problem-solving interview questions and answers

Q11. What methods or tools do you use to monitor an SD-WAN network?

Example: ‘Monitoring an SD-WAN network involves using various tools and methods to ensure it is secure and functioning correctly. The most efficient monitoring methods involve both real-time and historical data analysis. Flow analysis tools, for example, can be used to monitor bandwidth usage, while network performance management tools can be used to identify latency and jitter issues. In addition, organizations may monitor their networks for malicious behavior and threats by using intrusion detection systems and analytics. Network anomalies are also detected and analyzed using packet capture, log monitoring, and alerting. To ensure their networks are secure, organizations should also regularly conduct vulnerability scans and patch management.’

Q12. What security considerations should be taken when deploying an SD-WAN?

Example: ‘When deploying an SD-WAN, several security considerations should be considered. First, consider the overall network architecture and design. Ensure that all communications and devices are properly segmented and isolated from one another and that firewalls and other appropriate security measures protect each segment. Next, ensure that all communications between segments are encrypted to protect data from being intercepted.

Additionally, consider implementing a secure gateway to limit access to specific applications and services. When configuring the SD-WAN, use secure authentication methods such as multi-factor authentication to prevent unauthorized access. Also, set up logging and audit trails to track any activity on the system. Finally, keep the system and its components up-to-date with the latest security patches and updates. This will help to prevent the system from becoming vulnerable to known security threats.’

Q13. How do you ensure that your SD-WAN deployment is optimized for performance?

Example: ‘First, ensure that you have the right hardware and software to support the SD-WAN deployment. This includes selecting the right routers and switches and configuring them for the best performance. Additionally, you should use the latest SD-WAN software version and ensure it is patched and up-to-date. Second, create a secure and reliable network design that can handle the increased traffic from the SD-WAN deployment. Make sure that all of the components are properly connected and configured so that they can handle the expected traffic. Lastly, monitor the performance of the SD-WAN deployment regularly and adjust the configuration as needed to ensure optimal performance. You should also check for any possible issues or bottlenecks affecting the network’s performance so that you can address them immediately. By following these steps, you can ensure that your SD-WAN deployment is optimized for performance.’

Q14. What kind of data do you need to collect to measure SD-WAN performance?

Example: ‘To measure the performance of an SD-WAN, several key performances and operational metrics need to be collected. These metrics include network latency, jitter, throughput, packet loss, Quality of Service (QoS) performance, application performance, and availability. Also, data related to hardware device health and usage statistics should be collected, including utilization of resources such as CPU and memory and interface traffic statistics. Performance data can be collected using various tools, including network monitoring systems, packet analyzers, and software agents. This data should be used to create performance baselines and trend analysis reports so that potential performance issues can be identified and addressed quickly.’

Q15. How do you know if your SD-WAN is meeting your performance goals?

Example: ‘There are a few key metrics you should be monitoring to check if an SD-WAN is meeting performance goals. First, you should look at the latency of your connections. A low-latency connection will ensure that data is transferred quickly and efficiently. Second, you should monitor the throughput of your network. A high throughput indicates that more data is being transferred over the network, which can result in improved performance. Finally, you should also measure packet loss. Packet loss occurs when the destination does not receive data packets due to congestion or other problems. Packet loss can significantly impact performance, so it’s important to keep an eye on it. By monitoring these key metrics, you can determine if your SD-WAN is meeting your performance goals.’

Q16. What is the best way to deploy an SD-WAN solution in a large enterprise environment?

Example: ‘The best way to deploy an SD-WAN solution in a large enterprise environment is to start by assessing the current network infrastructure. This includes analyzing the current bandwidth requirements, network latency, and potential outages. Once this assessment is complete, you can evaluate different SD-WAN solutions that meet the organization’s needs.

Once you identify a suitable solution, you can configure and deploy the SD-WAN solution. This includes determining which sites will be connected, the network’s topology, and how the network will be secured. It will also involve setting up the necessary policies and protocols to ensure that the SD-WAN solution operates smoothly and efficiently.

The deployment process should also include testing and validating the SD-WAN solution to ensure it is working as expected. Additionally, you should monitor the network performance to identify any issues and take the necessary steps to address them. Finally, you must maintain and update the SD-WAN solutions on an ongoing basis to ensure that it remains secure, reliable, and efficient.’

Q17. What routing protocols are used to implement SD-WAN?

Example: ‘Routing protocols are used to implement SD-WAN to provide better performance and reliability for wide area networks. The main routing protocols for SD-WAN are DMCRP, OSPF,  EIGRP, and BGP. DMCRP is a low-overhead, fault-tolerant routing protocol that provides efficient packet forwarding without reliance on any centralized control. OSPF is an interior gateway protocol that calculates the best paths within an autonomous system based on link cost. EIGRP is a hybrid routing protocol that combines the features of distance vector and link-state routing protocols. BGP is an interdomain routing protocol for exchanging routing information between multiple autonomous systems. Each of these routing protocols has different advantages and disadvantages when used for SD-WAN, so careful consideration should be taken when deciding which protocol to use.’

Q18. How do you ensure that your SD-WAN is resilient to failure scenarios?

Example: ‘Ensuring the resiliency of an SD-WAN to failure scenarios requires a comprehensive strategy that prioritizes reliability, redundancy, and security. This includes measures such as deploying redundant links, both physical and virtual, across multiple access methods and service providers to ensure that if one link fails, another can take its place; setting up redundant devices, such as routers and switches, to minimize the risk of single points of failure; and leveraging automated processes to detect outages and automatically switch over to alternate paths. Security measures such as encryption and authentication should also be implemented to prevent malicious actors from compromising the network. Also, organizations should utilize network monitoring tools to ensure that their WAN is performing optimally and is resilient to failure scenarios.’

Q19. How do you manage and maintain an SD-WAN network?

Example: ‘Managing and maintaining an SD-WAN network requires careful planning and implementation. First, you should create a comprehensive network design incorporating the latest SD-WAN technologies and protocols. This will ensure maximum performance and security for your network. Once the network is in place, you should monitor the network’s performance regularly to identify any issues or areas of improvement. Additionally, it is essential to review the policies and procedures implemented on the network to ensure they are up-to-date and in line with best practices.

When it comes to maintenance, you should ensure that all hardware and software components are kept up to date. This includes patching, updating, and upgrading the software, firmware, and hardware on the network. Additionally, you should regularly test the network using tools such as stress tests, capacity tests, and penetration tests to identify potential security threats or performance issues. Finally, when changes or updates are made to the network, it is crucial to conduct a thorough audit to ensure that the changes align with the network’s design and do not disrupt its performance or security.’

Q20. What are the differences between a physical and virtual SD-WAN appliance?

Example: ‘The main difference between a physical and virtual SD-WAN appliance is that the former is a physical device installed on a customer’s premises, while the latter is a software-based solution that operates in the cloud.

A physical SD-WAN appliance typically requires more upfront capital investment and is typically less flexible than a virtual SD-WAN appliance. Physical SD-WAN appliances are purpose-built devices that provide wide-area network connectivity and secure network access for remote offices, branch locations, and mobile users. They are often pre-configured with the necessary features, such as routing, firewall, encryption, quality of service (QoS), and other networking capabilities. The physical SD-WAN appliances are typically managed by an IT administrator and require additional hardware components, such as routers and switches.

In contrast, a virtual SD-WAN appliance is a software-based solution that can be deployed in either a private or public cloud environment, allowing for a more cost effective and flexible deployment model. Virtual SD-WAN appliances are typically managed and maintained by a third-party provider, allowing organizations to focus their time and resources on other tasks. They are also more scalable than their physical counterparts, allowing organizations to quickly expand their network coverage as needed. Virtual SD-WAN appliances are more secure because they are constantly monitored by the provider and updated with the latest security patches and features.’

Key Takeaways SD-WAN Interview

Understanding SD-WAN is essential for professionals in the network and IT field, given its growing relevance in connecting dispersed business operations. The interview questions not only test your technical knowledge but also your ability to think critically about network solutions. My advice? Dive deep into the technology, understand its nuances, and keep abreast of industry developments. This preparation will not only help you in interviews but also equip you with knowledge that’s critical for navigating the future of networking.

Comprehensive Preparation: Familiarize yourself with the core concepts, benefits, and applications of SD-WAN. Knowing how to articulate these points clearly can demonstrate your expertise.

Real-World Applications: Be ready to discuss how SD-WAN can solve common networking challenges, showing your ability to apply theoretical knowledge in practical scenarios.

Stay Informed: Technologies evolve, so staying updated with the latest trends and developments in SD-WAN is crucial. Referencing authoritative sources can enhance your credibility.

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Emma Parrish, a seasoned HR professional with over a decade of experience, is a key member of Megainterview. With expertise in optimizing organizational people and culture strategy, operations, and employee wellbeing, Emma has successfully recruited in diverse industries like marketing, education, and hospitality. As a CIPD Associate in Human Resource Management, Emma's commitment to professional standards enhances Megainterview's mission of providing tailored job interview coaching and career guidance, contributing to the success of job candidates.

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