Senior Systems Administrator

Title: Senior Systems Administrator Location: Costa Mesa, California, United States

ABOUT THE ROLE

We are looking for a Senior Systems Administrator to independently administer, troubleshoot, maintain, and secure enterprise Windows and Linux systems in classified environments. Senior Systems Administrators are expected to perform nearly all routine and advanced administration with little to no assistance, serve as a technical escalation point, mentor other administrators, and lead operational work. Assistance should generally be limited to unfamiliar technologies, high-risk changes, architecture decisions, or issues requiring specialized engineering expertise.

WHAT YOU’LL DO

• Independently administer and troubleshoot Windows Server/desktop and Linux systems, Active Directory, enterprise authentication, permissions, services, applications, and domain-connected systems.
• Administer and troubleshoot enterprise Windows services including Group Policy (GPO), WSUS/patch management, DNS, DHCP, file services, certificates/PKI dependencies, and related system components.
• Create, modify, test, validate, and troubleshoot GPOs, including inheritance, precedence, OU targeting, security filtering, gpresult, and Resultant Set of Policy (RSoP).
• Administer WSUS or equivalent patching solutions, including synchronization, targeting, approvals, deployment status, failed updates, reporting, and patch-compliance remediation.
• Interpret DISA STIG requirements; use applicable STIG tools/checklists; implement and validate remediations, including GPO-based security configurations; document findings; and troubleshoot operational impacts.
• Independently administer and troubleshoot existing VMware, Hyper-V, or similar virtualization environments and virtual machines.
• Troubleshoot complex issues across operating systems, identity, applications, virtualization, storage, certificates, and network dependencies using logs and diagnostic tooling.
• Use PowerShell, Bash, and other scripting/automation methods for administration, bulk changes, data collection, troubleshooting, and repeatable tasks.
• Research and resolve unfamiliar issues using vendor documentation, technical references, logs, DISA guidance, and available tooling before requiring escalation.
• Plan and lead system changes, maintenance, upgrades, and migrations with implementation, validation, rollback, documentation, and change-control considerations.
• Serve as an escalation point and mentor for Junior Systems Administrators and Systems Administrators; provide peer review and technical guidance.
• Identify recurring problems, technical debt, security/configuration gaps, and process deficiencies and lead practical improvements within established architecture.

REQUIRED QUALIFICATIONS

• Active TS/SCI security clearance.
• Active CompTIA Security+ certification or higher DoD 8140/8570-aligned certification.
• Strong hands-on Windows and Linux systems administration experience with demonstrated ability to work independently.
• Hands-on experience with Active Directory, GPO administration/troubleshooting, enterprise patch management/WSUS, and domain-connected systems.
• Experience interpreting and remediating DISA STIG findings within secure or regulated environments.
• Working knowledge of VMware, Hyper-V, or comparable virtualization technologies.
• Strong understanding of TCP/IP, DNS, DHCP, IP addressing, subnetting, and network troubleshooting.
• Experience with PowerShell, Bash, or similar administrative scripting.
• Demonstrated ability to independently research and resolve complex technical problems, lead technical work, mentor others, and produce effective documentation.

PREFERRED QUALIFICATIONS

• Advanced Microsoft, Linux, VMware, networking, or cybersecurity certifications.
• Experience supporting engineering, manufacturing, or specialized technical applications.
• Experience leading infrastructure upgrades, migrations, maintenance events, or cross-functional technical efforts.