Senior Systems & Network Engineer (L3)

The Senior Systems & Network Engineer (L3) serves as the highest technical escalation point for complex infrastructure, cloud, network, and security issues across multiple client environments. This role is responsible for designing, implementing, optimizing, and supporting enterprise-grade IT infrastructure while ensuring high availability, security, scalability, and operational excellence. As an L3 Engineer, you will lead complex troubleshooting efforts, perform deep root cause analysis (RCA), and drive long-term solutions rather than temporary fixes. You will collaborate with internal engineering teams, mentor junior engineers, and participate in infrastructure modernization projects involving Microsoft 365, Azure, VMware, networking, cybersecurity, disaster recovery, and automation. This role requires exceptional technical expertise, strong analytical skills, and the ability to manage multiple enterprise environments within a Managed Service Provider (MSP) setting. Key Responsibilities Infrastructure Engineering Design, implement, and maintain enterprise Windows Server environments (2012–2025). Architect and manage Active Directory, Azure Active Directory (Entra ID), DNS, DHCP, DFS, PKI, Certificate Services, File Services, and Group Policy. Design and administer hybrid Microsoft 365 and Azure environments. Plan and execute infrastructure upgrades, migrations, consolidations, and modernization projects. Perform capacity planning, performance tuning, and infrastructure optimization. Enterprise Networking Design, deploy, and troubleshoot enterprise LAN, WAN, SD-WAN, VLANs, VPNs, routing, switching, wireless networks, and high-availability architectures. Configure and support Cisco, Meraki, SonicWall, Fortinet, Palo Alto, Ubiquiti, and similar enterprise networking platforms. Troubleshoot complex routing protocols, VPN tunnels, firewall policies, NAT, ACLs, QoS, and network segmentation. Support multi-site and Site-to-Site VPN environments. Microsoft Technologies Administer Microsoft 365, Exchange Online, SharePoint Online, Teams, OneDrive, Defender, and Intune. Design Conditional Access policies, MFA, Autopilot deployments, compliance policies, and endpoint security. Perform advanced Exchange administration, including hybrid Exchange environments. Design and manage enterprise Group Policy Objects (GPOs) and security baselines. Virtualization & Cloud Design and administer VMware vSphere, ESXi, vCenter, Hyper-V, and clustered virtualization environments. Manage storage, snapshots, HA, DRS, vMotion, replication, and virtual networking. Design and support Microsoft Azure infrastructure, including virtual networks, virtual machines, storage, identity, backup, monitoring, and governance. Support cloud migration and hybrid cloud initiatives. Security & Compliance Implement Zero Trust security principles and identity management best practices. Configure Microsoft Defender, Sentinel, Azure Security Center, Conditional Access, and endpoint security solutions. Perform vulnerability assessments, security remediation, patch management, and hardening activities. Investigate security incidents and assist with incident response and remediation. Ensure compliance with industry standards and security best practices. Backup & Disaster Recovery Design and maintain backup and disaster recovery solutions using Veeam, Datto, Barracuda, Azure Backup, and similar technologies. Perform backup validation, recovery testing, replication monitoring, and disaster recovery planning. Conduct periodic recovery drills and document recovery procedures. Automation & Process Improvement Develop automation scripts using PowerShell and other scripting technologies. Improve operational efficiency through automation, standardization, and process optimization. Build documentation, knowledge base articles, SOPs, and infrastructure standards. Identify recurring issues and implement permanent corrective actions. Troubleshooting & Escalations Serve as the final escalation point for complex infrastructure, networking, virtualization, and cloud issues. Perform advanced Root Cause Analysis (RCA) and implement permanent resolutions. Lead major incident investigations and post-incident reviews. Coordinate with vendors, Microsoft, hardware manufacturers, ISPs, and third-party providers during critical incidents. Leadership & Collaboration Mentor and coach L1 and L2 engineers through technical guidance and knowledge sharing. Participate in technical reviews, project planning, and change management. Collaborate with cross-functional teams to deliver infrastructure projects on time. Maintain accurate technical documentation and ensure adherence to ITIL best practices. Requirements Bachelor's degree in Computer Science, Information Technology, Engineering, or a related field (or equivalent professional experience). 5–8+ years of experience in Systems Administration, Network Engineering, Infrastructure Engineering, or a senior MSP environment. Extensive experience supporting enterprise-level Microsoft, networking, virtualization, and cloud technologies. Strong experience working in Managed Service Provider (MSP) environments supporting multiple clients. Technical Requirements Microsoft Technologies Windows Server 2012–2025 Active Directory Azure Active Directory (Entra ID) Microsoft 365 Exchange Online & Hybrid Exchange SharePoint Online Teams OneDrive Intune Group Policy DNS DHCP DFS PKI Certificate Services PowerShell Networking Cisco Meraki SonicWall Fortinet Palo Alto Ubiquiti VLANs Routing & Switching Site-to-Site VPN SSL VPN SD-WAN TCP/IP DNS NAT ACLs QoS Wireless Networking Virtualization VMware ESXi VMware vCenter VMware HA DRS vMotion Hyper-V Storage Management Cloud Microsoft Azure Azure Virtual Machines Azure Networking Azure Storage Azure Backup Azure Monitor Azure Security Hybrid Cloud Infrastructure Backup & Security Veeam Datto Barracuda Microsoft Defender Sentinel Endpoint Detection & Response (EDR) Vulnerability Management Disaster Recovery Business Continuity MSP Tools ConnectWise Kaseya Datto RMM NinjaOne N-able IT Glue ServiceNow Remote Monitoring & Management (RMM) Remote Desktop Protocol (RDP) Preferred Certifications Microsoft Certified: Azure Administrator Associate Microsoft Certified: Azure Solutions Architect Expert Microsoft Certified: Enterprise Administrator Expert VMware VCP Cisco CCNP Fortinet NSE Palo Alto PCNSE ITIL Foundation CompTIA Security+ Benefits 🏥 HMO Coverage 📋 Government-Mandated Benefits (SSS, PhilHealth, Pag-IBIG, 13th Month Pay) 🏠 Work-From-Home Setup 🌍 Work with International Clients and Enterprise Environments 🚀 Career Growth & Leadership Opportunities 📈 Continuous Technical Training & Certification Support 🤝 Collaborative Engineering Culture 💻 Company Equipment Provided (after 3 months)