JMA is restoring U.S. leadership in wireless technology at a critical time in the transition to 5G. It makes the world’s most advanced software-based 5G platform, designed, coded, and manufactured in Syracuse, NY at the only U.S.-owned 5G factory in the country.   Across its global tech centers, JMA makes 5G possible for organizations with the most critical connectivity demands in the world. JMA’s technology is ushering in a new era of connectivity for leading mobile carriers, the most iconic stadiums, major universities, leading healthcare centers, the busiest transit centers, and the U.S. Military.   5G is more than another G on your phone — it is a generational opportunity to change the way the world operates. Join the industry’s fastest growing technology company to shape that future today.  We are seeking an experienced Senior Systems Administrator  to manage and maintain our core enterprise infrastructure.    The Senior System Administrator is the organization’s technical lead for Windows Server and Active Directory infrastructure, with strong supporting ownership of Microsoft 365 (Office 365) and VMware virtualization. This is a senior individual-contributor role that combines deep hands-on administration with architecture, standards-setting, and mentorship. The Senior System Administrator designs and operates a secure, resilient, and well-governed environment — leading complex projects and migrations, defining operational best practices, and serving as the highest level of escalation for infrastructure and identity. The ideal candidate is a seasoned, security-minded engineer who can both go deep technically and raise the capability of the wider team. POSITION RESPONSIBILITIES: Active Directory & Windows Server (Primary Focus) Own the architecture, health, and roadmap of Active Directory — domains, forests, trusts, sites, OUs, and replication. Define and govern Group Policy strategy and standards for security, configuration, and standardization across the estate. Lead design and administration of core Windows Server roles and services, including DNS, DHCP, file/print, and PKI (AD CS). Set build, patching, and hardening standards for Windows Server; own server lifecycle and capacity planning. Establish identity and access-governance practices for user, group, and service accounts (least privilege, tiering). Maintain and troubleshoot domain controllers, FSMO roles, replication, and authentication (Kerberos/NTLM) at an expert level. Design and validate backup, restore, and disaster recovery strategy for Active Directory and server workloads. Identity, Security & Hybrid Connectivity Own hybrid identity strategy and synchronization between on-premises Active Directory and Microsoft Entra ID (Entra Connect). Define and enforce strong authentication standards, including multi-factor authentication (MFA) and conditional access. Establish and maintain server and endpoint security baselines, patching cadence, and hardening standards. Lead support for audits, access reviews, logging, and compliance requirements (e.g., SOC 2, ISO 27001, HIPAA as applicable). Drive detection of and response to identity- and infrastructure-related security events; lead root-cause analysis. Microsoft 365 / Office 365 Administration Provide senior-level administration of the Microsoft 365 tenant, including Exchange Online, SharePoint Online, OneDrive, and Microsoft Teams. Govern licensing, tenant configuration, and administrative role assignments. Design and maintain Microsoft 365 security and compliance controls (DLP, retention, email protection / Defender for Office 365). Lead tenant migrations and the adoption of new Microsoft 365 services; resolve complex mail flow and service issues.   Virtualization & VMware Own administration and design of VMware vSphere/ESXi and vCenter, including HA, DRS, and resource strategy. Lead VM provisioning standards, host upgrades, patching, and capacity planning for performance and availability. Manage storage and networking within the virtual environment (datastores, vSwitches, VLANs, vMotion). Lead troubleshooting and remediation of performance and availability issues across the virtualization stack.   Leadership, Projects & Collaboration Serve as the highest level of escalation for complex infrastructure, identity, and platform issues. Mentor and provide technical leadership to junior administrators and help desk staff; review work and share knowledge. Lead infrastructure projects, migrations, and upgrades from planning through implementation and handover. Define automation strategy and build tooling using PowerShell (and Microsoft Graph) to improve reliability and efficiency. Author and maintain architecture documentation, runbooks, standards, and configuration records. Partner with security, networking, and application teams; contribute to the infrastructure roadmap and technology decisions. Participate in and lead an on-call rotation for critical systems as required. REQUIRED SKILLS & EXPERIENCE: * 6+ years of system administration experience, including senior-level, hands-on Active Directory and Windows Server administration in production. * Expert working knowledge of Group Policy, DNS, DHCP, PKI, and core Windows Server roles and services. * Proven experience designing and governing identity, access, and least-privilege controls in a Windows-centric environment. * Strong, hands-on experience administering Microsoft 365 / Office 365 (Exchange Online, Teams, SharePoint, security). * Strong, hands-on experience administering VMware vSphere/ESXi and vCenter. * Experience leading projects, migrations, and disaster recovery planning for core infrastructure. * Demonstrated ability to mentor others and set technical standards and best practices. * Excellent troubleshooting, communication, and stakeholder-management skills with a security-focused mindset. * This role is based in Syracuse, NY and will require onsite presence.  PREFERRED SKILLS & EXPERIENCE: * Bachelor’s degree in Information Technology, Computer Science, or a related field (or equivalent experience). * Senior-level certifications such as Microsoft Certified: Windows Server Hybrid Administrator Associate, Identity and Access Administrator Associate (SC-300), or Microsoft 365 Administrator Expert. * Additional certifications such as VMware VCP-DCV or Azure Solutions Architect / Administrator (AZ-104). * Advanced scripting and automation with PowerShell and Microsoft Graph; familiarity with infrastructure-as-code. * Experience with hybrid identity (Entra Connect), Intune / endpoint management, Zero Trust, and security/compliance frameworks. * Solid networking fundamentals (VLANs, firewalls, VPN, load balancing). At JMA, our people are deeply committed to their work and we provide benefits to match. When you join JMA you have immediate access to everything you need. Whether you're looking for employee discounts, financial, legal and/or childcare resources and support, we have you covered. We believe in providing comprehensive health and wellness coverage along with monetary rewards towards health goals, in addition to numerous company-provided personal protection benefits at no additional cost to you.   At JMA, we don’t just accept differences — we embrace them. JMA is proud to be an equal opportunity workplace. We do not discriminate based upon race, religion, color, national origin, gender (including pregnancy, childbirth, or related medical conditions), sexual orientation, gender identity, gender expression, age, status as a protected veteran, status as an individual with a disability, or other applicable legally protected characteristic.