Job Summary: We are seeking a Senior IT Systems Administrator to lead the support, management, evolution, and optimization of our technological infrastructure and that of our clients. Key Responsibilities: 1. Lead second- and third-level technical support 2. Design, manage, and optimize virtualization environments 3. Participate in technology modernization and innovation projects We are looking for a Senior IT Systems Administrator with solid experience in corporate environments to lead the support, management, evolution, and optimization of our technological infrastructure and that of our clients. The role will be responsible for ensuring system availability, security, and scalability, as well as serving as the technical reference within the IT Department. Main Responsibilities * Lead second- and third-level technical support. * Design, manage, and optimize virtualization environments on Microsoft Hyper-V and VMware vSphere. * Advanced administration of Windows servers and hybrid environments. * Advanced configuration, hardening, and monitoring of Fortinet firewalls. * Management and evolution of network infrastructure based on Aruba electronics. * Design and implementation of IT security policies. * Backup management, disaster recovery plans (DRP), and business continuity. * Proactive monitoring and continuous improvement of system performance. * Coordination with technology vendors and manufacturers. * Participation in technology modernization and migration projects. * Creation of technical documentation and internal procedures. * Proposal of infrastructure improvements and standardization. Education * Degree in Computer Engineering, Telecommunications, or Higher Vocational Training (FP Superior) in ASIR. * Additional training in cybersecurity or advanced systems administration. * Minimum 5 years’ experience administering systems in enterprise environments and in the technologies required for this position. * Proven experience in virtualization, networking, and perimeter security. * Experience managing critical infrastructures with high availability. * Experience working collaboratively on project management and ITSM ticketing tools. Essential Technical Skills * Windows Server (advanced administration). * M365 and Microsoft Entra administration. * Active Directory, GPOs, DNS, DHCP. * Advanced virtualization (clustering, high availability, replication). * SQL database administration. * Network infrastructure (VLANs, routing, switching). * Firewalls, VPNs, network segmentation, and perimeter security. * Backup and disaster recovery strategies. * Storage using QNAP or similar NAS systems. * Scripting (PowerShell). We Offer * A stable project with direct impact on the company’s technology strategy. * Technical autonomy and decision-making authority. * Participation in modernization and innovation projects. * Continuous training and certification opportunities. * Competitive compensation package commensurate with experience and responsibilities.