Senior System Administrator

We are seeking a highly skilled Senior Systems Infrastructure Engineer to support, modernize, and lead critical infrastructure across a complex enterprise environment. This individual will be responsible for managing the full lifecycle of infrastructure systems, including planning, design, implementation, optimization, monitoring, security, disaster recovery, and eventual decommissioning.

This role requires deep technical expertise across Microsoft, VMware, Linux, cloud networking, endpoint management, and enterprise infrastructure architecture. The ideal candidate is hands‑on, strategic, calm under pressure, and comfortable owning high‑impact systems that support core business operations.

This person will serve as a senior technical resource for infrastructure projects, acquisitions, migrations, incident response, and long‑term technology planning.

• Own the full lifecycle of IT infrastructure systems from business requirement gathering through design, deployment, maintenance, monitoring, and retirement.
• Partner with business and technical stakeholders to understand infrastructure needs and translate them into scalable, secure technical solutions.
• Lead infrastructure refreshes, server upgrades, application deployments, storage replacements, and platform modernization initiatives.
• Apply structured change management, capacity planning, documentation, and decommissioning practices.
• Ensure infrastructure decisions align with business goals, security requirements, performance expectations, and operational continuity.

• Design, administer, and troubleshoot complex Microsoft infrastructure environments, including Active Directory, DNS, Group Policy, and Windows Server.
• Support Active Directory forest/domain architecture, trust relationships, mergers/acquisitions, UPN suffix planning, DNS forwarding, and baseline security policy implementation.
• Troubleshoot AD replication, site/subnet configuration, domain controller availability, GPO application, and authentication issues across distributed locations.
• Manage and support Microsoft Intune, Azure AD/Entra , Autopilot, device enrollment, application deployment, configuration profiles, and endpoint compliance.
• Investigate and resolve Autopilot enrollment failures, ESP issues, dynamic group assignment problems, and device policy/application deployment errors.
• Design, support, and optimize VMware vSphere and Microsoft Hyper‑V environments.
• Manage high‑availability virtualization platforms supporting mission‑critical workloads.
• Support vSphere HA, DRS, FT, clustering, live migration, storage connectivity, and performance tuning.
• Design and troubleshoot Windows Server Failover Clustering, Hyper‑V clusters, passthrough disks, Storage Spaces Direct, and related high‑availability architectures.
• Partner with application and database teams to build infrastructure designs for high‑I/O, high‑uptime systems such as SQL Server clusters.
• Administer Linux systems supporting enterprise and database workloads.
• Support Oracle Linux environments, including Unbreakable Enterprise Kernel and Red Hat Compatible Kernel considerations.
• Manage patching strategies for critical Linux systems, including zero‑downtime patching approaches using technologies such as Ksplice.
• Collaborate with database and application teams to maintain availability, performance, and security across Linux‑based infrastructure.
• Design and support secure hybrid connectivity between on‑premises data centers and public cloud environments.
• Support Azure and AWS networking architectures, including Express Route, Direct Connect, VNets, VPCs, subnets, route tables, NSGs, Security Groups, NACLs, UDRs, and private DNS.
• Segment cloud environments across web, application, and data tiers with proper routing and access controls.
• Implement and troubleshoot hybrid DNS resolution using Azure Private DNS, Route 53 Private Hosted Zones, and Route 53 Resolver.
• Ensure cloud network designs meet business requirements for security, throughput, performance, and resiliency.
• Participate in disaster recovery planning, testing, and execution for critical…