Mobileum
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We are hiring for Senior System Administrator at Cupertino, California, United States
Job Summary
We are seeking a highly experienced and self-motivated
Senior System Administrator
with a strong background in
Windows Server Administration ,
Microsoft 365 ,
Active Directory ,
Linux ,
networking , and
security infrastructure . This individual will play a key role in managing enterprise-level systems, securing digital environments, and ensuring optimal IT performance. The ideal candidate is up-to-date with the latest industry trends, capable of performing internal assessments, identifying gaps, and implementing robust solutions across a hybrid IT landscape. Key Responsibilities Windows & Server Administration Manage, monitor, and maintain Windows Server infrastructure, including patching, performance tuning, and configuration. Provide expert-level support for Windows-based systems, ensuring high availability and security. Administer and support Microsoft 365 services including Exchange Online, SharePoint, Teams, OneDrive, and Security & Compliance Center. Manage hybrid identity using Azure AD, SSO, and directory synchronization. Implement and monitor policies using Microsoft Purview, DLP, and conditional access. Active Directory & Identity Management Design, maintain, and secure on-premises Active Directory infrastructure. Perform regular audits, GPO configuration, OU structuring, and delegation of permissions. Email Security & Awareness Training Deploy and manage email security solutions targeting phishing, spoofing, spam, and malware. Conduct phishing simulation campaigns and user awareness training programs. Evaluate and recommend security tools and protocols to protect organizational communication. Firewall & Network Security Configure and maintain
FortiGate Firewalls , including VPN, policies, routing, and IPS/IDS. Monitor and analyze network traffic to identify and respond to threats and performance issues. Provide support for Linux servers (Debian, RHEL, CentOS), focusing on scripting, updates, and integration with AD. Assist with cross-platform compatibility and troubleshooting. Backup & Recovery Implement and manage enterprise backup solutions such as
Barracuda
and
Commvault . Define recovery point objectives (RPOs) and recovery time objectives (RTOs) for business continuity. Domain & Web Hosting Manage domain registrations, DNS configurations, SSL certificates, and hosting platforms. Liaise with hosting providers and ensure uptime and security of public-facing web services. End User Management End user computing and handle day to day operations related to Laptop, Desktop and Server Infra Provide support to VIP users and Senior Executives independently Required Skills & Qualifications Bachelor’s Degree in Computer Science, Information Technology, or a related field. Advanced knowledge on RHEL/Debian Operating System 12+ years of proven hands-on experience in system administration and infrastructure support. Advanced knowledge of Windows Server 2012–2022, Office 365, Azure AD, and email security tools. Hands on experience with FortiGate firewall and switches configuration and administration. Hands on experience on networking infra. Familiarity with industry best practices for cyber security and compliance. Knowledge of ITIL principles and implementation. Up to date with current technologies, trends, and security threats. Soft Skills Strong
presentation skills
and the ability to communicate complex technical concepts to non-technical stakeholders. Excellent
reporting and documentation
skills. Proactive, self-driven, and capable of identifying and closing operational gaps independently. Strong interpersonal and collaborative skills; able to work across teams and with vendors. Ability to manage time efficiently in a dynamic work environment. Preferred Certifications ITIL Foundation Certification RHEL Certification is preferred Experience:
12+ Years Seniority level
Seniority level Mid-Senior level Employment type
Employment type Full-time Job function
Job function Information Technology Industries Telecommunications, IT Services and IT Consulting, and Information Services Referrals increase your chances of interviewing at Mobileum by 2x Get notified about new System Administrator jobs in
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Senior System Administrator
with a strong background in
Windows Server Administration ,
Microsoft 365 ,
Active Directory ,
Linux ,
networking , and
security infrastructure . This individual will play a key role in managing enterprise-level systems, securing digital environments, and ensuring optimal IT performance. The ideal candidate is up-to-date with the latest industry trends, capable of performing internal assessments, identifying gaps, and implementing robust solutions across a hybrid IT landscape. Key Responsibilities Windows & Server Administration Manage, monitor, and maintain Windows Server infrastructure, including patching, performance tuning, and configuration. Provide expert-level support for Windows-based systems, ensuring high availability and security. Administer and support Microsoft 365 services including Exchange Online, SharePoint, Teams, OneDrive, and Security & Compliance Center. Manage hybrid identity using Azure AD, SSO, and directory synchronization. Implement and monitor policies using Microsoft Purview, DLP, and conditional access. Active Directory & Identity Management Design, maintain, and secure on-premises Active Directory infrastructure. Perform regular audits, GPO configuration, OU structuring, and delegation of permissions. Email Security & Awareness Training Deploy and manage email security solutions targeting phishing, spoofing, spam, and malware. Conduct phishing simulation campaigns and user awareness training programs. Evaluate and recommend security tools and protocols to protect organizational communication. Firewall & Network Security Configure and maintain
FortiGate Firewalls , including VPN, policies, routing, and IPS/IDS. Monitor and analyze network traffic to identify and respond to threats and performance issues. Provide support for Linux servers (Debian, RHEL, CentOS), focusing on scripting, updates, and integration with AD. Assist with cross-platform compatibility and troubleshooting. Backup & Recovery Implement and manage enterprise backup solutions such as
Barracuda
and
Commvault . Define recovery point objectives (RPOs) and recovery time objectives (RTOs) for business continuity. Domain & Web Hosting Manage domain registrations, DNS configurations, SSL certificates, and hosting platforms. Liaise with hosting providers and ensure uptime and security of public-facing web services. End User Management End user computing and handle day to day operations related to Laptop, Desktop and Server Infra Provide support to VIP users and Senior Executives independently Required Skills & Qualifications Bachelor’s Degree in Computer Science, Information Technology, or a related field. Advanced knowledge on RHEL/Debian Operating System 12+ years of proven hands-on experience in system administration and infrastructure support. Advanced knowledge of Windows Server 2012–2022, Office 365, Azure AD, and email security tools. Hands on experience with FortiGate firewall and switches configuration and administration. Hands on experience on networking infra. Familiarity with industry best practices for cyber security and compliance. Knowledge of ITIL principles and implementation. Up to date with current technologies, trends, and security threats. Soft Skills Strong
presentation skills
and the ability to communicate complex technical concepts to non-technical stakeholders. Excellent
reporting and documentation
skills. Proactive, self-driven, and capable of identifying and closing operational gaps independently. Strong interpersonal and collaborative skills; able to work across teams and with vendors. Ability to manage time efficiently in a dynamic work environment. Preferred Certifications ITIL Foundation Certification RHEL Certification is preferred Experience:
12+ Years Seniority level
Seniority level Mid-Senior level Employment type
Employment type Full-time Job function
Job function Information Technology Industries Telecommunications, IT Services and IT Consulting, and Information Services Referrals increase your chances of interviewing at Mobileum by 2x Get notified about new System Administrator jobs in
Cupertino, CA . San Jose, CA $77,000.00-$95,000.00 1 week ago User Support Lead and Junior System Administrator
Milpitas, CA $90,000.00-$102,000.00 1 month ago Milpitas, CA $105,300.00-$179,000.00 2 weeks ago San Mateo, CA $90,000.00-$120,000.00 1 week ago Fremont, CA $130,000.00-$140,000.00 1 month ago Sunnyvale, CA $70,000.00-$80,000.00 6 days ago Santa Clara, CA $100,000.00-$160,000.00 1 month ago San Jose, CA $160,000.00-$230,000.00 5 months ago Operations Specialist and System Administrator
San Francisco Bay Area $90,000.00-$110,000.00 4 weeks ago San Jose, CA $87,600.00-$186,000.00 1 week ago Hayward, CA $75,000.00-$85,000.00 3 days ago (Senior) Datacenter System Administrator
Fremont, CA $100,000.00-$185,000.00 4 days ago User Support & Junior Systems Administrator
Information Technology Specialist - Entry Level
San Jose, CA $20,000.00-$70,000.00 2 months ago Mountain View, CA $70,000.00-$130,000.00 1 week ago Sunnyvale, CA $80,000.00-$105,000.00 1 week ago Sys Admin (Workfront Configuration Consultant)
Systems Administrator / Technical Lead Process Control Systems
Manager, Systems and Database Administration
Newark, CA $101,505.00-$119,835.00 3 weeks ago Cloud Systems Administrator, Atlassian (Temporary Contract Staff Augmentation Role)
San Jose, CA $138,960.00-$208,440.00 1 day ago (1) Senior AWS DevOps and System Administrator
We’re unlocking community knowledge in a new way. Experts add insights directly into each article, started with the help of AI.
#J-18808-Ljbffr