What is a Security Engineer at Flexential?

As a Security Engineer at Flexential, you play a pivotal role in protecting the hybrid IT infrastructure that powers businesses across the country. Flexential is not just a standard enterprise; it is a provider of colocation, cloud, and connectivity solutions. This means your scope often extends beyond internal corporate security to the very backbone of the data center and cloud environments that customers rely on.

In this role, you act as the guardian of availability and integrity. You are expected to bridge the gap between traditional network engineering and modern cybersecurity operations. You will likely work on maintaining firewalls, securing virtualized environments, and troubleshooting complex connectivity issues that have security implications. The impact of your work is immediate—ensuring that critical customer workloads remain secure and accessible 24/7.

This position requires a "sole ownership" mentality. You are not just a cog in a machine; you are a problem solver who takes initiative. Whether you are mitigating a DDoS attack, configuring Access Control Lists (ACLs) for a new environment, or diagnosing why a specific server cannot reach the internet, you are the technical authority on the ground. It is a role for those who enjoy the hands-on reality of infrastructure security.

Getting Ready for Your Interviews

Preparation for Flexential is distinct because the company places a heavy emphasis on foundational technical knowledge and cognitive aptitude. You should prepare for a process that tests what you know (trivia and facts) just as much as how you think (troubleshooting and logic).

Technical Precision – 2–3 sentences describing: Flexential interviews often resemble a "technical rapid-fire" or "IT Jeopardy" format. Interviewers expect you to know specific networking facts, port numbers, and command-line arguments by heart. You must demonstrate instant recall of core concepts like CIDR notation and the OSI model without hesitation.

Diagnostic Logic – 2–3 sentences describing: A major component of the onsite evaluation involves whiteboard scenarios where you must diagnose a broken network or system. You will be evaluated on your ability to isolate variables, identify the root cause (e.g., a missing default gateway or a blocked port), and propose a fix in real-time.

Cognitive Aptitude – 2–3 sentences describing: Unlike many other tech companies, Flexential frequently utilizes standardized cognitive and personality assessments (IQ tests) early in the process. Success here requires a sharp mind capable of pattern recognition and logical reasoning, independent of your technical stack.

Cultural Alignment – 2–3 sentences describing: The company values a "Sole Ownership" mentality and high attention to detail. Interviewers look for candidates who are self-motivators, possess a sense of urgency, and can maintain professionalism even when challenged or when the environment becomes high-pressure.

Interview Process Overview

The interview process at Flexential is thorough and can be lengthy, often taking 3 to 4 weeks from application to decision. It generally begins with a recruiter screen that is more technical than average; expect to answer baseline networking questions right away. Following this, you will likely be asked to complete online assessments, including IQ and personality tests. These are gatekeepers—you must pass them to proceed to the hiring manager screen.

Once you clear the assessments, the process intensifies with technical screenings involving the hiring manager or a senior engineer. These calls verify your resume details and test your "book knowledge" of IT and security concepts. If successful, you will move to the final stage: a comprehensive onsite or panel interview (often video-based recently). This final round is rigorous, involving multiple team members, a "whiteboard" troubleshooting session, and potentially a computer-based skills assessment.

Candidates should expect a process that feels rigorous and traditional. The company places high value on validating your knowledge through testing. Be prepared for a mix of casual conversation and intense technical scrutiny. Communication can sometimes vary in speed, so proactive (but polite) follow-up is often necessary if you haven't heard back after a few days.

This timeline illustrates the typical funnel, starting with the critical cognitive assessments. Note that the "Technical Assessment" phase is often a combination of oral questioning and practical scenarios (whiteboarding). Plan your energy accordingly, as the final panel interview can last several hours and involve meeting 4–6 different stakeholders.

Deep Dive into Evaluation Areas

The evaluation for a Security Engineer at Flexential is heavily weighted toward Networking and Infrastructure. Based on candidate data, the interviewers are less interested in high-level policy and more interested in whether you understand the nuts and bolts of how data moves and how to secure it.

Networking Fundamentals

This is the single most critical area of evaluation. You cannot "hand-wave" your way through networking questions here. Interviewers expect precise, textbook-correct answers.

• Why it matters: As a data center and cloud provider, the network is the product. Security cannot exist without a deep understanding of transport.
• Evaluation: Expect rapid-fire questions on subnets, protocols, and routing.
• Strong performance: Answering immediately with correct calculations for IP ranges and distinct definitions of protocol functions.

Be ready to go over:

• CIDR and Subnetting: You must know how to calculate host ranges. (e.g., "How many usable hosts in a /24?").
• OSI Model: Understanding exactly what happens at Layer 2 vs. Layer 3 vs. Layer 4.
• Core Protocols: Deep knowledge of TCP/IP, DNS, DHCP, SSH, and FTP.
• Switching & Routing: VLANs, ACLs, and the function of a Default Gateway.

Example questions or scenarios:

• "How many hosts are available in a /24 CIDR block? (Don't forget the network and broadcast addresses, and the gateway!)"
• "Explain the difference between TCP and UDP."
• "Walk me through the handshake process."

Systems Administration (Linux & Windows)

Flexential environments are hybrid. You need to be comfortable navigating both Linux and Windows Server environments via command line.

• Why it matters: You will be securing and troubleshooting servers that run on these platforms.
• Evaluation: Questions often focus on administrative tasks, permissions, and basic security configurations.
• Strong performance: demonstrating familiarity with CLI tools and server roles (e.g., Active Directory, IIS, Apache/Nginx).

Be ready to go over:

• Linux CLI: Grep, chmod, chown, ps, top, and checking logs in /var/log.
• Windows Server: Remote Desktop (RDP), Active Directory basics, and Server 2008/2012/2016/2019 knowledge.
• Virtualization: VMware experience is highly valued. Understand hypervisors and virtual networking.

Example questions or scenarios:

• "How do you check active processes in Linux?"
• "What port does RDP use by default?"

Troubleshooting & Scenarios

This is usually the centerpiece of the onsite/panel interview. You will be given a broken scenario and asked to fix it.

• Why it matters: This tests your critical thinking and how you apply your theoretical knowledge to real incidents.
• Evaluation: You will likely stand at a whiteboard (or use a virtual equivalent) to trace a problem from user to destination.
• Strong performance: Asking clarifying questions, isolating the problem systematically (e.g., "Can I ping the gateway?"), and identifying the specific misconfiguration.

Be ready to go over:

• Connectivity issues: Users cannot access a website or server.
• Firewall Rules: Diagnosing dropped packets or incorrect ACL configurations.
• Latency/Performance: Identifying bottlenecks in a diagram.

Example questions or scenarios:

• "A user cannot access a specific website. The internet works for everyone else. Diagnose the issue."
• "Draw a network diagram and explain where you would place the firewalls."

Key Responsibilities

As a Security Engineer at Flexential, your day-to-day work combines operational support with security engineering. The role is often described by candidates as having a strong "Tier 3 Support" flavor, meaning you are the escalation point for complex technical issues that have stumped others.

You will be responsible for managing and maintaining security infrastructure, such as firewalls, intrusion detection systems, and VPN concentrators. A significant portion of your time will be spent responding to alerts and tickets—investigating why a connection is blocked, configuring new access rules for a customer, or mitigating a threat in real-time.

Collaboration is key. You will work closely with the Network Operations Center (NOC) and other engineering teams. You are expected to document your work thoroughly; "excellent documentation skills" are a core requirement. You will also need to communicate technical concepts to non-technical stakeholders, often explaining why a security measure is necessary or why a specific connection is failing.

Role Requirements & Qualifications

To be competitive for this role, you need a solid foundation in general IT infrastructure. Flexential looks for candidates who have "paid their dues" in support environments and have upskilled into security.

Must-have skills

• Networking Mastery: CCNA-level knowledge is virtually mandatory. You must be fluent in IP subnets, VLANs, Switching, and Routing.
• Operating Systems: Minimum 2 years of experience with Microsoft Server technologies and Linux/*nix platforms.
• Virtualization: Familiarity with VMware or similar hypervisor technologies.
• Security Fundamentals: Knowledge of firewalls, ACLs, VPNs, and basic threat landscapes.

Nice-to-have skills

• Certifications: Network+, Security+, CCNA, or Microsoft MCP/MCSA are highly desired and often serve as a shortcut to proving your knowledge.
• Scripting: Ability to automate tasks using Python, Bash, or PowerShell.
• Ticketing Systems: Prior experience working in an environment driven by tickets and SLAs.

Common Interview Questions

The questions below are drawn directly from candidate experiences at Flexential. Note the pattern: they are specific, binary (right/wrong), and focused on fundamentals. Do not expect vague, high-level theory discussions; expect to be tested on the details.

Networking & Infrastructure

This is the most common category. Review your "cheat sheets" for ports and protocols.

• "How many hosts are in a /24 CIDR block?" (Warning: Be precise about usable hosts vs. total addresses).
• "What is the default gateway and why is it important?"
• "Explain the function of ARP."
• "What port does SSH use? What about FTP/SFTP?"
• "Describe the difference between a switch and a router."

Troubleshooting Scenarios

These are often presented as "word problems" or whiteboard exercises.

• "A user complains they cannot reach a website. Walk me through how you troubleshoot this step-by-step."
• "You have a server that is unreachable. How do you determine if it's a network issue or a server issue?"
• "Diagnose a scenario where a firewall is blocking legitimate traffic."

Behavioral & Culture

Flexential assesses whether you can handle the pressure and ownership required by the role.

• "Tell me about a time you had to solve a problem with very little information."
• "How do you handle a situation where you disagree with a manager's technical decision?"
• "Why do you want to work at Flexential specifically?"
• "Describe a time you demonstrated 'sole ownership' of a project."

Frequently Asked Questions

Q: How difficult is the technical assessment? The difficulty is generally rated as "Medium" to "Hard," primarily because the questions can be trivial and specific. It is not necessarily conceptually difficult, but it punishes candidates who rely on Google for basic facts. You either know the answer, or you don't.

Q: What are the "IQ and Personality" tests? Flexential frequently uses standardized assessments (such as the CCAT or similar) to measure cognitive aptitude and personality traits. These are timed and cover math, verbal reasoning, and spatial logic. Take these seriously; they are often used as a hard filter before you meet the team.

Q: Is this a remote role? Historically, Security Engineer roles at Flexential have been onsite or hybrid, especially given the nature of data center work. However, policies evolve. You should clarify the current expectation (and any shift work requirements, as some roles cover overnight shifts) with the recruiter early on.

Q: What should I do if I don't hear back after the interview? Some candidates have reported delays or lack of follow-up ("ghosting"). If you haven't received an update within 3–4 business days of an interview, send a professional, polite follow-up email to both the recruiter and the hiring manager.

Other General Tips

Brush up on your "Trivia": Unlike modern interviews that focus on abstract system design, Flexential interviews often verify your memory. Review the exact number of hosts in different subnets (/24, /23, /30), common port numbers, and Linux command flags.

Master the Whiteboard: When asked to troubleshoot a "user cannot access website" scenario, draw it out. Draw the user, the switch, the router, the firewall, and the internet. Visually tracing the packet flow demonstrates the clarity of thought they are looking for.

Check your Ego: Some candidates have reported interviewers who challenge answers aggressively or nitpick details (e.g., the "technical Cisco answer"). If you are corrected, even if you think it's debatable, handle it with grace. Show that you are coachable and professional, rather than defensive.

Summary & Next Steps

The Security Engineer role at Flexential is a robust, hands-on position ideal for those who love the intersection of networking and security. It is a role where your technical knowledge is tested daily against real-world infrastructure challenges. If you enjoy troubleshooting, configuring complex environments, and taking ownership of critical uptime, this is a rewarding place to be.

To succeed, focus your preparation on the fundamentals. Do not overlook the basics of TCP/IP, subnetting, and CLI management. The interview process is designed to filter out those who only have surface-level knowledge. By walking into the interview ready to diagram a network, calculate a subnet in your head, and confidently explain your troubleshooting logic, you will set yourself apart from the majority of applicants.

The salary data indicates a competitive range for the role, though it may vary based on location (e.g., Denver vs. Charlotte) and shift differentials. Be sure to ask about the specific level of the role (e.g., Engineer I vs. Senior) as this significantly impacts the compensation band. Prepare well, stay professional, and good luck!