Question 1

Tell me about a time when you had to troubleshoot a critical network outage. How did you approach the problem and what was the outcome?

Accepted Answer

Last year, our main office experienced a complete network outage affecting 200+ users. I immediately initiated our incident response protocol, gathering information from multiple sources including monitoring systems and user reports. I systematically eliminated potential causes starting from the physical layer, discovered a failed core switch redundancy issue, and coordinated with vendors for emergency replacement while implementing a temporary workaround using backup routes. The network was restored within 4 hours, and I documented the incident thoroughly, leading to improved monitoring and faster failover procedures.

Question 2

Describe a situation where you had to implement a new network security policy that users initially resisted. How did you handle it?

Accepted Answer

When implementing a new VPN authentication policy requiring multi-factor authentication, several remote employees complained about the additional complexity. I organized training sessions explaining the security benefits and potential risks of data breaches, created simplified step-by-step guides, and established a dedicated support channel for the first month. I also worked with department heads to identify power users who could assist their colleagues. Within three weeks, compliance reached 98%, and user satisfaction surveys showed improved confidence in our security measures.

Question 3

Give me an example of when you had to learn a new networking technology or protocol quickly to solve a business problem.

Accepted Answer

Our company acquired a smaller firm using SD-WAN technology I hadn't worked with before. With only two weeks to integrate their network, I immediately enrolled in online training courses, set up a lab environment to practice configurations, and connected with the vendor's technical support team. I also reached out to networking forums and colleagues with SD-WAN experience. By combining theoretical learning with hands-on practice, I successfully integrated both networks on schedule while maintaining security standards and improving overall WAN performance by 30%.

Question 4

Explain the difference between routing and switching, and describe when you would use each in a network design.

Accepted Answer

Switching operates at Layer 2 of the OSI model and forwards frames within the same network segment using MAC addresses, while routing operates at Layer 3 and forwards packets between different networks using IP addresses. Switches are used to connect devices within a LAN, providing high-speed connectivity and creating collision domains for each port. Routers are used to connect different networks, making path decisions based on routing protocols and maintaining routing tables. In network design, I use switches for internal connectivity within VLANs and departments, while routers handle inter-VLAN routing, WAN connections, and internet connectivity. Modern Layer 3 switches can perform both functions, making them ideal for campus networks where routing and switching capabilities are needed in a single device.

Question 5

How would you configure a site-to-site VPN between two offices using Cisco ASA firewalls? Walk me through the key configuration steps.

Accepted Answer

To configure a site-to-site VPN between Cisco ASAs, I'd start with Phase 1 IKE configuration: define the ISAKMP policy with encryption (AES), hash (SHA), authentication (pre-shared key), and DH group. Next, configure the tunnel group with the peer IP and pre-shared key. For Phase 2, I'd create an IPSec transform set with ESP encryption and authentication methods. Then configure an ACL defining interesting traffic (networks to encrypt), create a crypto map linking the transform set, ACL, and peer, and apply it to the outside interface. Additional steps include configuring NAT exemption for VPN traffic, ensuring proper routing is in place, and configuring any necessary firewall rules to permit VPN traffic through the ASA.

Question 6

Describe the purpose and functionality of OSPF areas. Why would you implement a multi-area OSPF design?

Accepted Answer

OSPF areas are logical groupings of routers and links that help create a hierarchical network design and optimize routing efficiency. Area 0 serves as the backbone area, while other areas must connect to it directly or through virtual links. Multi-area OSPF designs provide several benefits: they reduce the size of topology databases and SPF calculations within each area, minimize LSA flooding by using area border routers (ABRs) to summarize routes, improve convergence times, and enable better network scalability. Areas also provide fault isolation - topology changes within one area don't trigger SPF recalculations in other areas. I would implement multi-area OSPF in large networks with hundreds of routers, geographically distributed locations, or when specific security or administrative boundaries need to be maintained.

Question 7

Your company is experiencing intermittent network slowdowns during peak business hours. How would you investigate and resolve this issue?

Accepted Answer

I'd begin by gathering baseline performance data and identifying patterns in the slowdowns - specific times, affected applications, or user groups. Using network monitoring tools, I'd analyze bandwidth utilization, packet loss, and latency across critical network segments during peak periods. I'd check for broadcast storms, examine switch port utilization, and review QoS policies to ensure critical traffic is properly prioritized. I'd also investigate whether the issues correlate with specific applications or scheduled tasks like backups. Based on findings, solutions might include implementing traffic shaping, upgrading bandwidth on congested links, optimizing routing paths, or deploying application-specific QoS policies. I'd create a remediation plan with measurable success criteria and schedule changes during maintenance windows while maintaining rollback procedures.

Question 8

A remote office reports they cannot access the main data center applications, but their internet connectivity is working fine. How do you troubleshoot this?

Accepted Answer

Since internet connectivity works but data center access fails, I'd focus on the WAN connection between sites. First, I'd verify the VPN or private circuit status and check for authentication failures or tunnel disconnections. I'd test connectivity to the data center from the remote office using traceroute to identify where packets are being dropped. I'd examine routing tables on both ends to ensure proper routes exist for the data center networks. If using MPLS or SD-WAN, I'd check service provider status and circuit utilization. I'd also verify that firewall rules and ACLs permit traffic between the sites and check NAT configurations. If the WAN connection appears functional, I'd investigate DNS resolution issues and verify that data center services are actually running and accessible from other locations.

Question 9

Where do you see yourself in your network engineering career in the next 5 years?

Accepted Answer

In the next five years, I see myself advancing to a senior network architect role where I can lead large-scale infrastructure projects and mentor other engineers. I plan to deepen my expertise in emerging technologies like SD-WAN, network automation, and cloud networking while obtaining advanced certifications such as CCIE or cloud-specific credentials. I'm particularly interested in the intersection of networking and security, and would like to become the go-to expert for designing secure, scalable network architectures. I also want to develop stronger business acumen to better align network solutions with organizational goals. Ultimately, I'd like to progress toward a network engineering management position where I can influence technology strategy while continuing to stay hands-on with cutting-edge networking technologies and leading a team of skilled professionals.

Question 10

What do you consider your greatest strength as a network engineer, and how has it benefited your previous employers?

Accepted Answer

My greatest strength is my systematic approach to complex problem-solving combined with strong communication skills. When facing network issues, I methodically work through potential causes while keeping all stakeholders informed throughout the process. This approach has helped me resolve critical outages 40% faster than our standard metrics and prevented several major incidents through proactive monitoring and analysis. At my previous company, this strength was particularly valuable during a major network refresh project where I identified potential compatibility issues during planning that could have caused weeks of downtime. My ability to translate technical concepts into business terms also helped secure budget approval for critical infrastructure upgrades by clearly demonstrating ROI and risk mitigation benefits to executive leadership.

Overview

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1. Where do you see yourself in your network engineering career in the next 5 years?

2. What do you consider your greatest strength as a network engineer, and how has it benefited your previous employers?

3. Describe an area where you'd like to improve your skills and how you plan to develop in that area.

4. Why are you interested in leaving your current position and what attracts you to our company?

5. How do you stay current with rapidly evolving networking technologies and industry trends?

6. Explain the difference between routing and switching, and describe when you would use each in a network design.

7. How would you configure a site-to-site VPN between two offices using Cisco ASA firewalls? Walk me through the key configuration steps.

8. Describe the purpose and functionality of OSPF areas. Why would you implement a multi-area OSPF design?

9. How would you troubleshoot a situation where users can ping internal servers but cannot access external websites?

10. Explain how VLANs improve network security and performance. How would you implement VLAN segmentation in a corporate environment?

11. What are the key differences between stateful and stateless firewalls, and when would you use each type?

12. How does BGP differ from IGP protocols like OSPF or EIGRP? When would you implement BGP?

13. Describe how you would implement redundancy in a network design to ensure high availability.

14. Tell me about a time when you had to troubleshoot a critical network outage. How did you approach the problem and what was the outcome?

15. Describe a situation where you had to implement a new network security policy that users initially resisted. How did you handle it?

16. Give me an example of when you had to learn a new networking technology or protocol quickly to solve a business problem.

17. Tell me about a time when you disagreed with a colleague or manager about a network design decision. How did you handle the situation?

18. Describe a project where you had to coordinate with multiple teams to upgrade network infrastructure. What challenges did you face?

19. Tell me about a time when you made a mistake in network configuration that caused problems. How did you handle it and what did you learn?

20. Describe a situation where you had to work under extreme time pressure to resolve a network issue. How did you manage the stress and ensure quality work?

21. Give me an example of when you had to explain a complex network issue to non-technical stakeholders. How did you ensure they understood?

22. Tell me about a time when you identified a security vulnerability in your network. What steps did you take to address it?

23. Describe a time when you had to mentor a junior team member or help a colleague develop their networking skills. What was your approach?

24. Your company is experiencing intermittent network slowdowns during peak business hours. How would you investigate and resolve this issue?

25. A remote office reports they cannot access the main data center applications, but their internet connectivity is working fine. How do you troubleshoot this?

26. Management wants to implement a guest Wi-Fi network that's completely isolated from the corporate network but still provides internet access. How would you design this solution?

27. Your organization is migrating to a new office location. What networking considerations and steps would you plan for this migration?

28. A security audit reveals that your network has several compliance violations. How would you prioritize and address these issues?

29. Your company wants to implement SD-WAN to replace traditional MPLS connections. How would you approach this network transformation project?

30. Users are complaining about poor video conferencing quality, especially during company-wide meetings. How would you diagnose and improve this situation?

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