Enterprise Active Directory (AD) SME – Infrastructure Lead

About the role

We are seeking a senior Infrastructure Subject Matter Expert to own and evolve the core Active Directory, Windows, and identity ecosystems for a global financial services institution. This hands‑on role focuses on high‑availability architecture, Tier‑0 security, and seamless hybrid identity integration.

Key responsibilities

• Oversee, optimise, and engineer the enterprise Windows Server landscape for maximum performance and uptime.
• Design, maintain, and support complex Active Directory environments, including forest/domain design, OU structures, GPOs, and replication topologies.
• Lead integration of hybrid identity solutions, bridging on‑premise AD with Microsoft Entra ID and Microsoft 365.
• Architect and maintain secure authentication and federation platforms, including ADFS and Single Sign‑On.
• Secure, design, and govern Tier‑0 AD assets with strict privileged‑access segregation.
• Administer the enterprise Public Key Infrastructure and Certificate Authority servers.
• Drive major infrastructure upgrades, automation initiatives (heavy PowerShell), and continuous service improvements.
• Ensure alignment with security, compliance, and ITIL standards during incident resolution and system changes.

Required profile

• 15+ years of experience engineering and administering large‑scale Windows infrastructure.
• Deep hands‑on expertise in on‑premise and hybrid Active Directory, Microsoft Entra ID Connect, and M365 identity syncing.
• Strong background in ADFS, core networking (TCP/IP, DNS, DHCP), and PKI/CA management.
• Security‑first mindset with experience managing Tier‑0 infrastructure and privileged‑access frameworks.
• Proven automation skills using PowerShell.

Required skills

• Active Directory (on‑premise & hybrid)
• Microsoft Entra ID Connect
• Microsoft 365 identity synchronization
• ADFS
• Windows Server
• TCP/IP, DNS, DHCP
• Public Key Infrastructure (PKI) and Certificate Authority
• PowerShell automation