Senior Systems Administrator

Are you a hands-on Systems Administrator who enjoys solving complex infrastructure problems and working across a variety of client environments?
We’re looking for a
Senior Systems Administrator
to join a growing managed IT services provider supporting clients across the Greater Toronto Area. This is a hands-on role with a strong focus on
virtualization, Microsoft 365, Azure, and networking .
The ideal candidate has strong infrastructure experience, is comfortable working directly with clients, and can take ownership of technical issues from troubleshooting through to resolution.
Work Type:
Fully Onsite - 5 days a week in-office or visiting client sites;
on-call andafter hourssupport whenrequired
Location :Toronto, ON
Work Type :Thisis a newly created position
What You’ll Do:
Manage and troubleshoot
virtualized infrastructure, including Nutanix HCI environments
Administer and support
Microsoft 365
environments, including Exchange Online, SharePoint, Teams, OneDrive, and user/license management
Support
Azure and Entra ID
environments, including hybrid identity and cloud infrastructure
Configure, maintain, and troubleshoot
network infrastructure, including LAN/WAN, VLANs, firewalls, VPNs, and Wi‑Fi
Serve as a senior escalation point for complex technical issues and Level 1/2 tickets
Support server, endpoint, operating system, and infrastructure‑related issues across client environments
Lead and support infrastructure projects, including migrations, upgrades, and implementations
Monitor system health and proactively identify and resolve potential issues
Maintain accurate technical documentation, network diagrams, and infrastructure standards
Work directly with clients and vendors to resolve technical issues and deliver solutions
Provide technical guidance and mentorship to junior technicians
Apply security best practices across client systems and infrastructure
What We’re Looking For:
5+ years of experience in Systems Administration, Infrastructure Engineering, or a similar role
Experience working within an
MSP, managed services, or multi‑client environment
Hands‑on experience administering Nutanix HCI, including cluster management and AHV/VM administration
Strong experience administering
Microsoft 365, including Exchange Online, SharePoint, Teams, and OneDrive
Experience with
Azure and Microsoft Entra ID, including hybrid environments
Solid understanding of
networking, including LAN/WAN, VLANs, firewalls, VPNs, and routing
Experience with Windows Server and on‑premises Active Directory
Experience with RMM and PSA platforms;
HaloPSA and NinjaOne
are an asset
Strong troubleshooting and problem‑solving skills
Experience mentoring, coaching, or providing technical direction to junior technicians
Strong client‑facing communication skills and the ability to work with both technical and non‑technical stakeholders
Strong organizational skills and the ability to manage multiple client environments and competing priorities
Nice to Have
Cybersecurity experience from a
systems/infrastructure administration perspective
Experience with
SentinelOne, Microsoft Defender, or other EDR/MDR platforms
FortiGate or other firewall experience
Microsoft 365 security experience, including Conditional Access, MFA, Intune, and DLP
Experience with infrastructure migrations to Azure/Microsoft 365
ITIL Foundation or working knowledge of ITIL practicesExperience supporting law firms or professional services organizations
Experience with operational technology (OT), building automation, or commercial property environments
Nutanix or Microsoft certifications
What Makes This Role Exciting?
Technical Variety:
Work across virtualization, cloud, Microsoft 365, networking, and infrastructure
Client Exposure:
Work directly with a diverse client base and become a trusted technical resource
Hands‑On Environment:
Take ownership of real infrastructure challenges and projects
Technical Growth:
Continue developing your expertise across modern infrastructure and cloud technologies
Leadership Opportunity:
Mentor junior technicians and play a key role in supporting the broader technical team
Base Salary: $90,000 - $120,000
Performance Bonus Eligibility
Paid Time Off & Extended Health Benefits(Medical/Dental/Vision)
Professional development, training, and certification opportunities
We’re committed to diversity and inclusion. Need accommodation during the hiring process? Let us know, we’re here to support you!
AI Use Disclosure:
STACK IT uses AI‑enhanced tools to support initial candidate screening and interview note analysis. All assessments and hiring decisions remain human‑led.
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