Senior Windows Specialist

Senior Windows Specialist - 12 months - Brussels, Belgium

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About the Role

RELYzIT Talent is seeking a Senior Windows Specialist for a high-impact, freelance assignment with our client in Brussels. This is a unique opportunity to join a mission-critical environment where your expertise will directly shape the security and reliability of national infrastructure. You’ll be part of a select group of builders trusted to deliver at the highest level, working exclusively onsite at our client’s secure facilities.

Why This Role Matters

In a world where digital threats evolve daily, our client’s operations depend on robust, secure, and expertly managed IT systems. As a Senior Windows Specialist, you will be instrumental in safeguarding sensitive information, ensuring operational continuity, and enabling secure digital transformation. Your work will directly impact national security and the resilience of critical systems, making this role vital to the organization’s mission and the country’s safety.

What You’ll Be Doing

• Designing, implementing, and maintaining complex Windows environments to the highest security standards


• Administering and optimizing Microsoft SCCM, Exchange, and VMware infrastructures


• Managing and securing Active Directory and LDAP directories


• Developing and automating processes using PowerShell scripting


• Applying ZeroTrust and EDR principles to enhance system security and resilience


• Coaching and supporting team members, fostering a culture of continuous improvement


• Collaborating in Agile teams to deliver impactful solutions


• Ensuring compliance with ITIL best practices and organizational policies


• Contributing to incident response, troubleshooting, and root cause analysis


• Staying ahead of emerging threats and technologies, proactively recommending improvements

What We’re Looking For

• 10+ years of proven experience in Windows system administration and related technologies


• Expertise in Microsoft Windows, SCCM, Exchange, VMware, LDAP, and PowerShell scripting


• Confirmed experience with EDR, ZeroTrust, ITIL, and Agile methodologies


• Strong coaching and team leadership skills


• Proactive, ownership-driven mindset with a passion for problem-solving and impact


• Ability to thrive in high-security, high-stakes environments


• Nice to have: Experience with Docker and Linux

Technical Skills

• Microsoft Windows (Expert)


• Microsoft SCCM (Expert)


• Exchange (Expert)


• VMware (Expert)


• LDAP (Expert)


• PowerShell scripting (Expert)


• EDR (Confirmed)


• ZeroTrust (Confirmed)


• ITIL (Confirmed)


• Agile (Confirmed)


• Coaching/Team (Confirmed)


• Docker (Nice to have)


• Linux (Nice to have)

Language Proficiency

• Fluent in Dutch or French, with good knowledge of the other national language (Dutch or French)


• Good command of English

Other Requirements

• Belgian nationality is mandatory


• In possession of a "very secret" or "top secret" security clearance, or willing to obtain one


• All work must be performed onsite at our client’s secure facility in Brussels (no remote work possible)


• Minimum 10 years of confirmed experience in relevant roles

Project Details

• Freelance position


• 12-month contract


• Onsite in Brussels, Belgium