Senior System Administrator at DAG Industries Nigeria Limited

Role Overview

• The Senior Systems Administrator is responsible for the design, implementation, optimization, security, and high-level support of an organization\'s critical IT infrastructure (servers, networks, cloud environments, storage, and identity systems). They ensure high availability, performance, security compliance, and disaster recovery readiness while mentoring junior staff and leading complex projects.

Key Responsibilities

Core Systems & Infrastructure

• Install, configure, maintain, and optimize Windows and Linux servers
• Manage Active Directory, Group Policy, DNS, DHCP, and identity services
• Maintain and monitor virtualized environments (VMware, Hyper-V, or similar)
• Support and manage cloud infrastructure (Azure, AWS, or hybrid)
• Ensure high availability, performance tuning, patching, and lifecycle management
• Maintain documentation, runbooks, and infrastructure standards

Network

• Architect and manage core network infrastructure — LAN/WAN, VLANs, subnets, routing, switching, and wireless networks  
• Configure, troubleshoot, and optimize network devices (routers, switches, firewalls, load balancers, proxies, VPN concentrators)  
• Implement and maintain secure network access — site-to-site VPNs, remote access VPNs, Zero Trust Network Access (ZTNA), MFA enforcement  
• Administer firewalls and security gateways (Palo Alto, Fortinet, Cisco ASA/Firepower, Azure Firewall, AWS Network Firewall) rule management, NAT, threat prevention, IPS/IDS integration

Security & Hardening

• Implement and maintain MDM, endpoint security, EDR, antivirus, and patch management
• Apply system hardening best practices (CIS benchmarks, least-privilege, secure baselines)
• Manage firewalls, VPNs, NAC, and network segmentation in collaboration with network teams
• Monitor logs and alerts; support incident response and root-cause analysis
• Implement MFA, conditional access, privileged access management (PAM)
• Conduct vulnerability scanning, remediation, and security improvements
• Support compliance initiatives (ISO 27001, SOC2, internal policies, etc.)

Operations & Reliability

• Monitor system health, availability, and capacity
• Troubleshoot complex incidents with infrastructure, networking, identity, and applications
• Manage backup, disaster recovery, and business continuity
• Reduce operational risk by improving automation, observability, and resilience
• Participate in on-call rotations and escalation workflows
• Experience with Intune, MDM, endpoint compliance

Collaboration & Improvement

• Partner with IT, security, and engineering teams to design scalable solutions
• Support internal teams with advanced technical troubleshooting
• Mentor junior administrators and promote best practices
• Continuously evaluate and recommend improvements to tooling, architecture, and security posture

Required Qualifications

• Bachelor’s degree in computer science, or related field (or equivalent experience)
• 5+ years in system administration / infrastructure engineering
• Strong experience with Windows Server and Linux
• Deep knowledge of Active Directory, identity, GPO, DNS
• Experience managing cloud or hybrid environments
• Hands-on experience with endpoint protection, patching, and system hardening
• Solid understanding of networking fundamentals (TCP/IP, VLANs, firewalls)
• Proficiency configuring firewalls, VPNs, and access control
• Experience with backup, DR, and monitoring tools

Security-Focused Experience

• Implementing security controls, MFA, conditional access
• Managing privileged accounts and access boundaries
• Supporting incident response and forensic triage
• Familiarity with vulnerability scanning and remediation workflows
• Understanding of Zero Trust principles and defense-in-depth

Nice-to-Have

• Experience with SIEM tools  
• Knowledge of EDR/XDR platforms (Defender, CrowdStrike, SentinelOne)
• Cloud certifications (AWS Solutions Architect, Azure Administrator, Google Cloud Professional)
• Microsoft certifications (Windows Server Hybrid Admin, Azure Administrator)
• Linux certifications  
• Zero Trust Architecture implementation experience