Senior IT Systems Administrator — Secure, Mission-Critical IT

ISN; Bethesda (MD); On-site; USD 110,000 - 140,000; Full time

Benefits offered by this job

Comprehensive Medical Coverage

Flexible Spending Accounts (FSA)

Disability insurance (short & long)

Basic Life Insurance

401(k) Retirement Plan

Paid Time Off from day one

Professional growth and leadership dev

Job summary

ISN Corporation seeks a senior IT System Administrator to support and maintain our IT infrastructure. The role oversees Windows servers, Active Directory, DNS, DHCP, and core networking while delivering advanced technical support across the organization.

Ideal candidates have 8–10 years of system/network administration experience, strong Microsoft 365 and Azure AD skills, and hands-on VoIP and NAS/SAN experience. ISN offers a Drug-Free Workplace and equal opportunity employment.

Qualifications

• Experience administering Windows Server ecosystems and core services.
• Strong knowledge of AD, DNS/DHCP, and Group Policy.
• Experience managing Microsoft 365, Azure AD, Teams, and SharePoint.
• Good understanding of security practices, patch management, and incident handling.

Responsibilities

• Administer Windows servers, Active Directory, DNS, DHCP, and Group Policy.
• Support switches, firewalls, VPNs, and wireless networks.
• Configure and troubleshoot VoIP phones, call routing, and SIP/hosted voice systems.
• Maintain NAS/SAN storage appliances and shared drives.
• Manage Microsoft 365, Azure AD/Entra ID, Teams, and SharePoint.
• Provide Tier 3 support and handle escalations.
• Monitor backups, performance, patches, and updates.
• Maintain documentation, SOPs, and asset inventory.
• 8–10 years of experience in system/network administration.
• Strong expertise in Windows Server, Microsoft 365, and networking.
• Hands-on VoIP and network storage experience.
• Strong security practices and patch management.
• Ability to work independently and manage multiple priorities.

Skills

Windows Server administration

Network administration

Microsoft 365 administration

Security best practices

Documentation & SOPs

Tools

Active Directory

DNS

DHCP

Group Policy

Azure AD/Entra ID

SharePoint

PowerShell

Job description

ISN Corporation seeks a senior IT System Administrator to support and maintain our IT infrastructure. The role oversees Windows servers, Active Directory, DNS, DHCP, and core networking while delivering advanced technical support across the organization.

Ideal candidates have 8–10 years of system/network administration experience, strong Microsoft 365 and Azure AD skills, and hands-on VoIP and NAS/SAN experience. ISN offers a Drug-Free Workplace and equal opportunity employment.