Senior Systems Administrator

About the role

We are seeking an experienced Senior Systems Administrator to join a fast‑growing enterprise IT team in the Janesville area. This hands‑on role will own the reliability, performance, and security of a complex Windows‑based infrastructure spanning on‑premises servers, cloud services, storage, and networking.

Key responsibilities

• Administer and optimize enterprise Windows Server environments for high availability and security.
• Manage Hyper‑V virtualization, including deployments, upgrades, patching, and performance tuning.
• Maintain Microsoft 365 services such as Exchange Online, Teams, and SharePoint.
• Design, implement, and support Azure subscriptions, identity services, and cloud resources.
• Oversee Active Directory, Group Policy, DNS, DHCP, and related identity management.
• Support SAN storage, backup solutions, and disaster‑recovery processes.
• Configure and troubleshoot networking components: firewalls, switches, wireless, VPNs, and WAN links.
• Administer Cisco Firepower and SonicWall firewalls, including security policies and threat prevention.
• Manage Aruba and Ubiquiti switching, VLANs, routing, and wireless networks.
• Monitor infrastructure health, lead incident response, and perform root‑cause analysis.
• Participate in migrations, upgrades, cloud initiatives, and other infrastructure projects.
• Document configurations, procedures, and network diagrams.
• Collaborate with security teams to apply best‑practice controls.
• Automate routine tasks using PowerShell and other scripting tools.
• Mentor junior staff and provide technical leadership.

Required profile

• 7+ years of enterprise systems administration experience.
• Deep expertise in Windows Server, Active Directory, and Microsoft identity services.
• Proven experience with Microsoft 365 and Azure environments.
• Hands‑on Hyper‑V virtualization background.
• Strong enterprise networking knowledge, including firewalls, VPNs, and wireless.
• Experience with Cisco Firepower, SonicWall, Aruba, and Ubiquiti platforms.
• Ability to lead complex incident investigations and mentor team members.

Required skills

• Windows Server
• Active Directory
• Group Policy
• DNS & DHCP
• Microsoft 365 (Exchange Online, Teams, SharePoint)
• Azure
• Hyper‑V
• SAN storage & backup technologies
• Cisco Firepower
• SonicWall firewalls
• Aruba switching
• Ubiquiti networking
• PowerShell scripting