Job Title: Senior System Administrator
Department: IT / Infrastructure & Security
Experience: 4–7 Years

1. Job Summary

We are looking for an experienced Senior System Administrator to manage, secure, maintain, and optimize the organization's IT infrastructure, servers, cloud environments, networks, Microsoft 365 services, and cybersecurity systems.

The ideal candidate should have strong hands-on experience in Windows and Linux server administration, cloud infrastructure, Microsoft 365 administration, email security, network security, backup and disaster recovery, malware and ransomware prevention, monitoring, and incident management.

The candidate will be responsible for ensuring the availability, performance, confidentiality, and integrity of company systems and data while protecting corporate email accounts and infrastructure from phishing, unauthorized access, malware, ransomware, and other cyber threats.

2. Key Responsibilities

A. Server and System Administration

- Install, configure, maintain, and troubleshoot Windows Server and Linux environments.
- Manage Active Directory, Group Policy, DNS, DHCP, file servers, user accounts, and access permissions.
- Monitor server performance, availability, CPU, memory, disk utilization, and system capacity.
- Perform operating system upgrades, security patching, updates, and routine maintenance.
- Troubleshoot complex server, operating system, software, and infrastructure issues.
- Maintain production and internal IT systems to meet agreed uptime and performance requirements.
- Manage user onboarding, offboarding, access provisioning, and permission revocation.

B. Cloud and Infrastructure Management

- Manage cloud infrastructure on AWS, Microsoft Azure, or Google Cloud Platform.
- Configure and maintain virtual machines, storage, cloud networking, security groups, IAM, and access policies.
- Manage virtualization platforms such as VMware and Microsoft Hyper-V.
- Monitor cloud resource utilization, availability, performance, and infrastructure costs.
- Implement infrastructure monitoring, alerting, automation, and capacity planning.
- Coordinate with development and DevOps teams to support application hosting, deployment, and production infrastructure.
- Maintain infrastructure documentation, architecture diagrams, and configuration records.

C. Microsoft 365 and Corporate Email Security

- Administer and secure Microsoft 365, Exchange Online, Outlook, and corporate email services.
- Implement Multi-Factor Authentication (MFA), Conditional Access, and least-privilege access policies.




- Configure and maintain Microsoft Defender for Office 365 or equivalent email security solutions.
- Implement and validate SPF, DKIM, and DMARC to protect the company's email domain from spoofing and impersonation.
- Configure anti-phishing, anti-spam, anti-malware, malicious URL, and attachment protection policies.
- Monitor suspicious sign-ins, unusual login locations, repeated authentication failures, mailbox rule changes, and unauthorized email forwarding.
- Prevent and investigate Business Email Compromise (BEC), phishing, credential theft, and unauthorized email account access.
- Review Microsoft 365 audit logs, Entra ID sign-in logs, mailbox activity, and security alerts regularly.
- Detect and investigate suspicious OAuth application permissions and unauthorized third-party integrations.
- Establish secure email account onboarding, offboarding, password reset, and access revocation procedures.
- Ensure appropriate retention, audit logging, and recovery settings are configured for corporate email services.

D. Cybersecurity, Malware and Ransomware Prevention

- Implement security controls to protect company systems against malware, ransomware, viruses, spyware, trojans, and other cyber threats.
- Deploy and manage endpoint protection and Endpoint Detection and Response (EDR) solutions, such as Microsoft Defender for Endpoint.
- Monitor security alerts and investigate suspicious processes, malicious scripts, unauthorized software, and abnormal system behavior.
- Implement OS and application hardening, firewall rules, secure configurations, and endpoint security policies.
- Conduct regular vulnerability assessments and coordinate remediation of identified security weaknesses.
- Protect servers, laptops, employee workstations, cloud infrastructure, and corporate networks against unauthorized access and exploitation.
- Monitor and investigate suspicious network traffic, brute-force attempts, unauthorized access, and other indicators of compromise.
- Implement controls to reduce risks associated with malicious attachments, harmful links, compromised credentials, and social engineering.
- Maintain secure backups,



including immutable or offline copies where appropriate, to minimize the impact of ransomware.
- Perform root cause analysis after security incidents and implement preventive measures to avoid recurrence.

E. Network and Access Security

- Manage LAN, WAN, VPN, VLANs, DNS, DHCP, routing, switching, and network connectivity.
- Configure and maintain firewalls, network access controls, and secure remote access.
- Monitor network availability, traffic, suspicious connections, and potential security incidents.
- Implement secure administrator access, privileged account management, and least-privilege permissions.
- Review user accounts, administrative privileges, service accounts, and third-party access periodically.
- Secure Wi-Fi, remote access, and employee devices according to company security policies.
- Support network segmentation and restrict unnecessary access to critical servers and business systems.

F. Security Monitoring and Incident Response

- Monitor infrastructure and security alerts through available monitoring and security platforms.
- Investigate compromised email accounts, suspicious logins, malicious mailbox rules, and unauthorized forwarding configurations.
- Respond promptly to suspected cyber incidents by disabling or restricting compromised accounts, revoking active sessions and tokens, and resetting credentials as appropriate.
- Isolate affected endpoints or servers when necessary to prevent the spread of malware or ransomware.
- Coordinate incident response, evidence preservation, remediation, and recovery activities.
- Escalate critical security incidents to management, vendors, or cybersecurity specialists when required.
- Maintain incident reports, timelines, root cause analysis, and corrective action records.
- Develop, document, and periodically test security incident response procedures.

G. Backup, Disaster Recovery and Business Continuity

- Implement and maintain backup policies for servers, databases, applications, email, and critical business data.
- Monitor backup jobs and resolve failures promptly.
- Maintain disaster recovery and business continuity plans.
- Conduct periodic backup restoration and disaster recovery tests.
- Define recovery time objectives (RTO) and recovery point objectives (RPO) in coordination with stakeholders.
- Verify that backup systems are appropriately isolat

Pay: ₹10,000.00 - ₹40,000.00 per month

Advantages:

- Health insurance
- Leave encashment
- Paid time off
- Provident Fund

Work Location: In person

📌 Senior System Administrator (Ahmedabad)
🏢 Vrinsoft Technology
📍 Ahmedabad