What You Will Do: Serve as a Principal Systems Administrator supporting Windows and Linux enterprise environments, responsible for the design, implementation, maintenance, patching, and troubleshooting of Windows Server, Windows 11, RHEL 7/8/9, and virtualized infrastructure within a large-scale, mission-critical environment operating 24x7x365. Experience with Windows and Linux patching, vulnerability remediation, and compliance activities, including STIG/EVAL STIG implementation, SCAP/ACAS support, log collection, and close coordination with Cyber Security teams to maintain continuous compliance with DoD and regulatory requirements.