Senior System Administrator

About the role

Senior System Administrator role supporting secure, reliable, and high-performing enterprise technology environments. Manage a broad technology landscape spanning Windows Server, Active Directory, AWS, Azure, and Microsoft 365. Combine hands‑on administration, cloud operations, infrastructure deployments, security, automation, and technical support. Contribute to new environment builds, system upgrades, disaster recovery, monitoring, and capacity planning. Serve as an escalation‑level resource troubleshooting complex infrastructure issues while meeting defined service levels. Collaborate with security and client teams, document operational standards, and mentor junior administrators. Position is remote or hybrid within the U.S., with occasional customer travel and scheduled on‑call responsibilities.

Responsibilities

• Administer, maintain, troubleshoot, and support enterprise server, cloud, network, and collaboration infrastructure per client requirements and service standards.
• Build, deploy, configure, and maintain Windows Server environments, Active Directory, DNS, DHCP, Group Policy, certificate services, file and print services, and related infrastructure.
• Manage AWS infrastructure including EC2, S3, EBS, VPC, IAM, Route 53, and CloudWatch; support Azure IaaS, Entra ID, and hybrid identity/directory synchronization.
• Administer Microsoft 365 services including Exchange Online, SharePoint Online, OneDrive, Teams, and Intune.
• Support network‑related services such as VPNs, load balancers, firewalls, routers, switches, and associated policy changes.
• Perform system maintenance, upgrades, patching, security baseline implementation, and configuration changes across on‑premises and cloud environments.
• Monitor infrastructure performance, availability, capacity, resource utilization, cloud consumption, and costs to identify risks and optimization opportunities.
• Administer backup, replication, and disaster recovery processes; participate in periodic recovery and restore testing.
• Automate recurring administrative activities using PowerShell, Bash, infrastructure‑as‑code, or comparable scripting/configuration‑management technologies.
• Follow established change‑management, configuration‑management, security, and compliance procedures; ensure changes are reviewed, approved, documented, and implemented.
• Partner with security teams to implement identity, endpoint, cloud security, and configuration controls supporting a secure infrastructure.
• Provide escalation‑level technical support for system, cloud, and network incidents while working within defined SLA requirements.
• Develop and maintain runbooks, technical documentation, standards, and knowledge‑base content; mentor junior administrators and support personnel.
• Contribute to new site and environment deployments, operational improvements, and initiatives to increase reliability and administrative efficiency.

Requirements

• Bachelor’s degree in a relevant field or an equivalent combination of education and professional experience.
• 5+ years of hands‑on systems administration experience, preferably in enterprise or managed‑services environments.
• Advanced expertise in Windows Server administration, including Active Directory, Group Policy, DNS, DHCP, certificate services, and MFA.
• Hands‑