Senior Microsoft Infrastructure Administrator

Senior Microsoft Infrastructure Administrator

Location: Remote, with occasional onsite support in Washington, DC
Employment requirements: Ability to work without sponsorship and the ability to obtain a Public Trust

Position Overview

System One IT is seeking a Senior Microsoft Infrastructure Administrator to support an enterprise federal environment. This individual will serve as a senior technical authority across Microsoft 365, Azure Government, Microsoft Entra ID, Exchange Online, Microsoft Teams, Intune, Defender, and related Microsoft cloud services.
The successful candidate will provide hands-on administration and engineering support, independently resolve complex cross-platform issues, lead Microsoft infrastructure improvements, and mentor junior administrators. This position requires strong technical ownership, sound judgment, and experience operating in a regulated federal or comparably secure enterprise environment.

Key Responsibilities

Microsoft 365 Administration

• Administer and engineer Microsoft 365 services, including Exchange Online, SharePoint Online, OneDrive, and Microsoft Teams
• Lead Microsoft 365 updates, feature rollouts, and configuration changes through established change-management practices
• Monitor Microsoft 365 service health, performance, and security posture
• Develop configuration standards, governance documentation, and technical procedures
• Support Microsoft 365 licensing and service optimization
• Evaluate Microsoft roadmap updates and recommend platform improvements

Azure Government and Entra ID

• Administer Azure Government and Microsoft Entra ID services
• Configure Conditional Access, multifactor authentication, single sign-on, identity governance, and Privileged Identity Management
• Support Zero Trust initiatives through identity-based security controls and least-privilege access
• Manage Azure subscriptions, resource groups, role-based access control, and policy enforcement
• Support identity assurance requirements, including IAL2
• Maintain Microsoft cloud services in alignment with FedRAMP and federal cybersecurity requirements

Endpoint Management and Security

• Administer Microsoft Intune for device management, application deployment, configuration, and compliance enforcement
• Manage Microsoft Defender for Endpoint policies and support security incident response
• Develop endpoint security baselines aligned with NIST SP 800-53 requirements
• Support Windows endpoint patching and software deployment
• Troubleshoot complex endpoint enrollment, compliance, policy, and application issues

Exchange Online and Microsoft Teams

• Administer Exchange Online mail flow, transport rules, mailbox configurations, and email security policies
• Manage Microsoft Teams policies, governance, meetings, and service configurations
• Configure and maintain DMARC, DKIM, SPF, and Microsoft Defender for Office 365
• Support Microsoft Teams Rooms and audiovisual integrations
• Serve as the senior escalation point for messaging and collaboration incidents

Security, Compliance, and Governance

• Maintain Microsoft platform configurations in accordance with FISMA, FedRAMP, NIST SP 800-53, and organizational security requirements
• Administer Microsoft Purview capabilities, including data loss prevention and information protection
• Support Zero Trust Architecture aligned with NIST SP 800-207 and OMB M-22-09
• Apply least-privilege and separation-of-duties principles
• Support security assessments, audit evidence collection, and remediation activities

Incident Management and Technical Leadership

• Serve as the senior escalation point for complex Microsoft infrastructure incidents
• Independently diagnose and resolve cross-domain Microsoft platform issues
• Maintain incident records, troubleshooting runbooks, technical procedures, and knowledge articles
• Coordinate with service desk, network, security, and infrastructure teams
• Mentor junior Microsoft infrastructure administrators
• Review technical work for accuracy, quality, and adherence to standards

Required Qualifications

• 6 to 8 or more years of hands-on enterprise Microsoft infrastructure administration and engineering experience
• Experience administering Microsoft 365, Azure Government, and Microsoft Entra ID in a federal or comparably regulated enterprise environment
• Strong hands-on experience with Microsoft Intune and Microsoft Defender for Endpoint
• Experience implementing Zero Trust principles across Microsoft platforms
• Experience independently resolving complex Microsoft infrastructure issues
• Knowledge of FedRAMP-authorized Microsoft services and federal security requirements
• Strong PowerShell scripting skills for Microsoft 365 and Azure administration
• Familiarity with ITSM platforms such as ServiceNow
• Knowledge of ITIL change and incident management practices

Required Technical Expertise

• Microsoft 365 administration
• Exchange Online, SharePoint Online, OneDrive, and Microsoft Teams
• Azure Government
• Microsoft Entra ID
• Conditional Access and Privileged Identity Management
• Identity governance and role-based access control
• Microsoft Intune
• Microsoft Defender for Endpoint
• Microsoft Defender for Office 365
• Microsoft Purview
• PowerShell
• Zero Trust Architecture
• FedRAMP, FISMA, and NIST SP 800-53

Required Certifications

Candidates must hold current, active versions of all three certifications:
• Microsoft Certified: Microsoft 365 Administrator Expert
• Microsoft Certified: Azure Administrator Associate, AZ-104
• Microsoft Certified: Identity and Access Administrator Associate, SC-300

Preferred Certifications

• Microsoft Certified: Azure Solutions Architect Expert, AZ-305
• Microsoft Certified: Security Operations Analyst Associate, SC-200
• Microsoft Certified: Information Protection and Compliance Administrator Associate, SC-400
• CompTIA Security+ or an equivalent security certification

System One, and its subsidiaries including Joulé and Mountain Ltd., are leaders in delivering outsourced services and workforce solutions across North America. We help clients get work done more efficiently and economically, without compromising quality. System One not only serves as a valued partner for our clients, but we offer eligible employees health and welfare benefits coverage options including medical, dental, vision, spending accounts, life insurance, voluntary plans, as well as participation in a 401(k) plan.

System One is an Equal Opportunity Employer. All qualified applicants will receive consideration for employment without regard to race, color, religion, sex (including pregnancy, childbirth, or related medical conditions), sexual orientation, gender identity, age, national origin, disability, family care or medical leave status, genetic information, veteran status, marital status, or any other characteristic protected by applicable federal, state, or local law.

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