Top Network Segmentation Interview Questions and Answers

Introduction

Network segmentation involves dividing an extensive network into smaller sections or subnets. Each segment operates as its mini-network, enhancing security by controlling traffic flow. This practice is vital in cybersecurity because it limits the scope of potential breaches. Organizations can contain and mitigate the impact of cyberattacks by isolating sensitive data or critical systems within separate segments. Network segmentation is a fundamental strategy for bolstering cybersecurity defenses and safeguarding against various threats. Our Network Segmentation questions and answers will help you ace your cybersecurity interview!

Q1: What Device Is Used To Split Up Extensive Networks?

A: Routers, switches, and bridges help divide large networks into smaller ones, called network segments.

Q2: What's The Idea Behind Network Segmentation?

A: Network segmentation breaks an extensive network into smaller parts or subnets. Each segment acts like its own little network, giving security teams more control over the traffic coming into their systems

Q3: What Are The Downsides Of Network Segmentation?

A: Scaling issues: As the network grows, you have to make more segments or upgrade existing ones, which can be costly. Performance problems: Adding more network devices, like firewalls or routers, can slow the overall network.

Q4: How Many Types Of Network Segmentation Are There?

A: There are two types: physical and virtual. Physical segmentation uses specific hardware to create segments. It's the most secure but also the hardest to manage.

Q5: Why Is Network Segmentation Beneficial?

A: It offers different security setups for each network segment, allowing better traffic control, improving network performance, and boosting security.

Q6: What's A Single Network Segment?

A: In simple terms, it's an electrical connection between networked devices using a shared medium, according to Ethernet standards. For example, in older Ethernet setups, a segment could be a single coax cable with devices connected to it.

Q7: What's A Segmentation Firewall?

A: This is a standard method by which a firewall is placed at a network boundary. All traffic passing that boundary goes through the firewall through physical connections or virtual local area networks (VLANs).

Q8: What's The Blue Team's Biggest Challenge When Dealing With Network Segmentation?

A: One of the biggest challenges that the Blue Team may face when dealing with network segmentation is getting an accurate view of what is currently implemented in the network. This happens because, most of the time, the network will grow according to demand, and its security features are not revisited as it expands. For large corporations, this means rethinking the entire network and possibly rearchitecting it from the ground up.

Q9: What Is An In-Depth Defense Approach?

A: The whole idea behind the defense-in-depth approach is to ensure that you have multiple layers of protection, that each layer will have its own set of security controls, which will end up delaying the attack, and that the sensors available in each layer will alert you to whether or not something is happening. In other words, it means breaking the attack kill chain before the mission is fully executed. But to implement a defense-in-depth approach for today's needs, you need to abstract yourself from the physical layer and think purely about layers of protection according to the entry point.

Q10: Why Is It Important To Familiarize Yourself With Networking Capabilities?

A: While you have complete control over the on-premises network and configuration, the cloud virtual network will be something new for you to manage. For this reason, you must familiarize yourself with the networking capabilities available in the cloud provider's IaaS and how to secure this network. Using Azure as an example, one way to quickly assess how this virtual network is configured is to use Azure Security Center. Azure Security Center will scan the Azure virtual network that belongs to your subscription and suggest mitigations for potential security issues.

Q11: How Can You Defend Endpoints?

A: When planning defense in depth for endpoints, you must think beyond computers. Nowadays, an endpoint is any device that can consume data. The application dictates which devices will be supported, and as long as you are working in sync with your development team, you should know what devices are supported. 

In general, most applications will be available for mobile devices and computers. Some other apps will go beyond this and allow accessibility via wearable devices, such as Fitbit. Regardless of the form factor, you must perform threat modeling to uncover all attack vectors and plan mitigation efforts accordingly. Some of the countermeasures for endpoints include:

• Separation of corporate and personal data/apps (isolation)

• Use of TPM hardware protection

• OS hardening

• Storage encryption

Q12: What Are Some Ways To Aggregate Resources For Network Segmentation?

A: Some ways to aggregate resources can be based on the following aspects:

• Business objectives: Using this approach, you can create VLANs that have resources based on standard business objectives

• Level of sensitivity: Assuming that you have an up-to-date risk assessment of your resources, you can create VLANs based on the risk level (high, low, medium)

• Location: For large organizations, sometimes it is better to organize the resources based on location

• Security zones: Usually, this type of segmentation is combined with others for specific purposes, for example, one security zone for all servers that partners access

While these are standard methods of aggregating resources, which could lead to network segmentation based on VLANs, you can have a mix of all these

Q13: What Are Some Best Practices You Can Follow For Security In Network Segmentation?

A: The following best practices can help you with your network segmentation:

• Use SSH to manage your switches and routers

• Restrict access to the management interface

• Disable ports that are not used

• Leverage security capabilities to prevent MAC flooding attacks

• Leverage port-level security to prevent attacks, such as DHCP snooping

• Make sure that you update the switch's and router's firmware and operating systems

Q14: How Can You Secure Remote Access To The Network?

A: Networking segmentation planning would only be complete by considering the security aspects of remote access to your corporate network. Even if your company does not have employees working from home, chances are that an employee will be traveling and need remote access to the company's resources at some point. 

If this is the case, you need to consider not only your segmentation plan but also a network access control system that can evaluate the remote system before allowing access to the company's network; this evaluation includes verifying the following details:

• The remote system has the latest patches

• The remote system has antivirus-enabled

• The remote system has a personal firewall enabled

• That the remote system is compliant with mandate security policies

Q15: What Is The Responsibility Of Network Access Control (NAC)?

A: The NAC is responsible for validating the remote device's current health state and performing software-level segmentation by allowing the source device to only communicate with predefined resources located on premises. This adds an extra layer of segmentation and security. 

Although the diagram does not include a firewall, some companies may opt to isolate all remote access users in one specific VLAN and have a firewall between this segment and the corporate network to control the traffic coming from remote users. This is usually used when you want to restrict the access users will have when accessing the system remotely.

It is also essential to have an isolated network to quarantine computers that do not meet the minimum requirements to access network resources. This quarantine network should have remediation services that scan the computer and apply the appropriate remediation to enable it to gain access to the corporate network.

Q16: Explain In Detail About Virtual Network Segmentation

A: When planning your virtual network segmentation, you must first access the virtualization platform to see available capabilities. However, you can start planning the core segmentation using a vendor-agnostic approach since the core principles are the same regardless of the platform. Note that there is isolation within the virtual switch; in other words, the traffic from one virtual network is not seen by the other. 

Each virtual network can have its subnet, and all virtual machines within the virtual network can communicate among themselves. Still, it won't traverse to the other virtual network. What if you want to have communication between two or more virtual networks? In this case, you need a router (it could be a VM with a routing service enabled) that has multiple virtual networks adapters, one for each virtual network.

As you can see, the core concepts are very similar to the physical environment, and the only difference is the implementation, which may vary according to the vendor. Using Microsoft Hyper-V (Windows Server 2012 and beyond) as an example, it is possible to implement some security inspections using virtual extensions at the virtual switch level. Here are some examples that can be used to enhance your network security:

• Network packet inspection

• Intrusion detection or firewall

• Network packet filter

Q17: How Can You Avoid A VM Traversing To A Physical Network And Reaching Another Host?

A: Often, the traffic originating in one VM can traverse the physical network and reach another host connected to the corporate network. For this reason, it is essential always to think that, although the traffic is isolated within the virtual network, if the network routes to other networks are defined, the packet will still be delivered to the destination. Make sure that you also enable the following capabilities in your virtual switch:

• MAC address spoofing: This prevents malicious traffic from being sent from a spoof address

• DHCP guard: This prevents virtual machines from acting or responding as a DHCP server

• Router guard: This prevents virtual machines from issuing router advertisement and redirection messages

• Port ACL (access control list): This allows you to configure specific access control lists based on MAC or IP addresses

These are just examples of what you can implement in the virtual switch. If you use a third-party virtual switch, you can extend these functionalities.

Q18: How Do Attackers Disrupt A Company's Productivity By Attacking Its Infrastructure And Service?

A: Attackers can disrupt your company's productivity by attacking its infrastructure and services. It is essential to realize that even in an on-premises-only scenario, you still have services, but the local IT team controls them. Your database server is a service: it stores critical data consumed by users, and if it becomes unavailable, it will directly affect the user's productivity, which will have a negative financial impact on your organization. In this case, you must enumerate your organization's services to its end users and partners and identify the possible attack vectors.

Once you identify the attack vectors, you must add security controls to mitigate these vulnerabilities—for example, enforce compliance via patch management, server protection via security policies, network isolation, backups, etc. All these security controls are layers of protection, and they are layers of protection within the infrastructure and services realm. Other layers of protection will need to be added for different areas of the infrastructure

Q19: What Is Hybrid Cloud Network Security?

A: According to McAfee's report, Building Trust in a Cloudy Sky, released in April 2017, hybrid cloud adoption grew threefold in the previous year, representing an increase from 19% to 57% of the organizations surveyed. In a nutshell, it is realistic to say that your organization will have some connectivity to the cloud sooner or later, and according to the normal migration trend, the first step is to implement a hybrid cloud.

When designing your hybrid cloud network, you need to consider everything previously explained and plan how this new entity will integrate with your environment. Many companies will adopt the site-to-site VPN approach to directly connect to the cloud and isolate the segment that has cloud connectivity. While this is a good approach, it usually has an additional cost and requires extra maintenance. Another option is to use a direct route to the cloud, such as the Azure ExpressRoute.

Q20: How Do You Set Up A Physical Network Segmentation?

A: The first step to establishing an appropriate physical network segmentation is understanding the logical distribution of resources according to your company's needs. This debunks the myth that one size fits all, which, in reality, it doesn't. You must analyze each network case by case and plan your network segmentation according to the resource demand and logical access. 

For small and medium-sized organizations, it might be easier to aggregate resources according to their departments—for example, those that belong to the financial department, human resources, operations, etc. If that's the case, you could create a virtual local area network (VLAN) for each department and isolate the resources per department. This isolation would improve performance and overall security.

The problem with this design is the relationship between users/groups and resources. Let's use the file server as an example. Most departments will need access to the file server at some point, so they will have to cross VLANs to access the resource. Cross-VLAN access will require multiple rules, different access conditions, and more maintenance. For this reason, large networks usually avoid this approach, but you can use it if it fits your organization's needs.

Conclusion

JanBask Training's cybersecurity courses offer comprehensive network segmentation training and other crucial cybersecurity concepts. Through their courses, beginners can gain in-depth knowledge of network segmentation, its importance in cybersecurity, and practical implementation strategies. With hands-on exercises and real-world scenarios, learners can develop practical skills that are highly relevant in interviews and professional cybersecurity roles.