Oracle Linux 8: System Administration I — Lesson 3: Networking, Hostnames, DNS, SSH, Firewall, and Time Services

Learning Objectives

• Explain the architecture, workflow, or business purpose behind NetworkManager connections, addresses, routes, and interface state.
• Apply hostname, resolver, DNS, troubleshooting tools, and connectivity tests and OpenSSH server, keys, client configuration, and secure remote access in a controlled scenario.
• Validate outcomes and troubleshoot risks involving firewalld zones, services, ports, chrony, and network change validation.

Detailed Topics

• NetworkManager connections, addresses, routes, and interface state
• hostname, resolver, DNS, troubleshooting tools, and connectivity tests
• OpenSSH server, keys, client configuration, and secure remote access
• firewalld zones, services, ports, chrony, and network change validation

Instructor Demonstration

Demonstrate NetworkManager connections, addresses, routes, and interface state within a new Oracle Linux application host prepared, secured, validated, and handed to production support, then capture the exact configuration, command, transaction, report, model, query, code, or process evidence that proves the result for lesson 3.

Hands-On Exercise

Implement a controlled exercise covering hostname, resolver, DNS, troubleshooting tools, and connectivity tests and OpenSSH server, keys, client configuration, and secure remote access, then introduce and resolve an exception involving firewalld zones, services, ports, chrony, and network change validation while preserving before-and-after evidence.

1. Confirm the environment, identities, inputs, dependencies, risks, and expected outcome.
2. Complete the course-specific configuration, development, analysis, or process workflow.
3. Capture settings, commands, data, outputs, logs, reports, screenshots, calculations, or test results.
4. Compare the observed result with acceptance criteria and document corrective action.

Scenario Analysis

• Identify the technical or business decision that must be made.
• Compare valid approaches and their security, performance, reliability, cost, compliance, and support trade-offs.
• Define rollback, recovery, ownership, communication, and evidence requirements.

Troubleshooting Guidance

Diagnose issues across NetworkManager connections, addresses, routes, and interface state, hostname, resolver, DNS, troubleshooting tools, and connectivity tests, OpenSSH server, keys, client configuration, and secure remote access, firewalld zones, services, ports, chrony, and network change validation without making an unverified production change. Separate symptoms from causes, gather evidence, test the smallest reversible correction, rerun validation, and record preventive action.

Validation Checklist

• The requirement, scope, inputs, dependencies, and expected result are documented.
• The result is reproducible and supported by course-specific evidence.
• Normal, boundary, failure, security, performance, and operational conditions are reviewed.
• Exceptions, rollback, ownership, and the next improvement priority are recorded.

Lesson Outcome

Learners can apply Networking, Hostnames, DNS, SSH, Firewall, and Time Services in a realistic Oracle Linux 8: System Administration I scenario and validate the result with documented evidence.