CCNA 200-301 v1.1

6.6 Configuration Management Mechanisms: Ansible and Terraform

1. What is Configuration Management?

• Definition: Configuration management is the process of automating the setup, deployment, and management of network devices, servers, and applications.
• Goal: Ensure that devices and systems are configured correctly, consistently, and can be updated automatically without manual intervention.
• Importance in IT Networks:
  • Reduces human errors.
  • Saves time when configuring many devices.
  • Ensures that configurations are consistent across all devices.

Think of it as a tool that allows network engineers to write instructions once and automatically apply them to all devices in the network.

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2. Ansible

What is Ansible?

• Ansible is a configuration management tool that automates tasks on servers, switches, and routers.
• It is agentless, which means you don’t need to install any software on the network devices—it uses SSH or APIs to communicate.

Capabilities of Ansible

1. Automate Configuration:
   • Can configure routers, switches, firewalls, servers, and cloud services automatically.
   • Example: You can push VLAN configurations to all switches at once.
2. Deploy Applications:
   • Automatically install and update software on multiple devices.
3. Consistency & Compliance:
   • Ensures all devices have the same configuration.
   • Example: Make sure all routers have the same SNMP settings.
4. Orchestration:
   • Coordinate multiple tasks in a specific order across devices.
   • Example: Update server software, then update firewall rules, then reboot devices.
5. Idempotency:
   • Ansible only makes changes if needed. If the configuration is already correct, it won’t change anything.
   • This prevents accidental misconfigurations.

How it works (simplified)

• You write a playbook (instructions file in YAML format)
• Ansible reads the playbook and applies the configuration to the target devices.

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3. Terraform

What is Terraform?

• Terraform is a Infrastructure as Code (IaC) tool.
• It is mostly used to provision and manage cloud infrastructure like virtual machines, networks, and storage.
• While Ansible is often used for configuring existing devices, Terraform is used to create the devices and resources themselves.

Capabilities of Terraform

1. Provisioning Infrastructure:
   • Automatically create servers, virtual networks, and firewalls in the cloud.
   • Example: Launch 10 virtual machines in AWS with predefined network settings.
2. Manage Infrastructure:
   • Track and update infrastructure over time.
   • Example: Add more servers or update network configurations without manually changing each one.
3. Version Control:
   • Infrastructure configurations are written in files (HCL language), which can be tracked like software code.
   • You can roll back to previous versions if needed.
4. Plan & Apply:
   • Terraform shows a plan of what changes will be made before actually applying them.
   • This reduces mistakes when changing configurations.
5. Idempotency:
   • Like Ansible, Terraform only makes changes if the current state doesn’t match the desired state.

How it works (simplified)

• You write a Terraform file describing the resources you need (servers, networks, etc.).
• Terraform reads it, compares it to what exists, and creates or updates resources to match the configuration.

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4. Key Differences Between Ansible and Terraform

Feature	Ansible	Terraform
Purpose	Configure devices and servers	Create/manage infrastructure
Agent Required?	No	No
Type of Automation	Configuration management & orchestration	Infrastructure provisioning
Common Use in IT	Update network devices, install software	Provision cloud servers & networks
Idempotency	Yes	Yes

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5. Why This is Important for CCNA

• Modern networks rely on automation and consistent configurations.
• Knowing the capabilities of Ansible and Terraform helps you understand:
  • How networks are managed at scale.
  • The difference between configuring devices and creating infrastructure.
• CCNA may test you on what these tools can do, not the detailed commands.

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6. Exam Tip

Version control / plan before apply (Terraform)

Remember:

Ansible = configure existing devices

Terraform = create and manage infrastructure

Key capabilities to remember for exam questions:

Automation

Consistency / Idempotency

Orchestration (Ansible)

Provisioning (Terraform)

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