Chapter 5 of 6 · Cisco CCNA 200-901 DEVASC

Infrastructure and Automation

Model driven programmability, tools, CI/CD, IaC, Ansible, Bash, YANG, diffs and sequence diagrams.

  • 8topics
  • 41 minfast track
  • 3diagrams and exhibits
  • 20%of the exam
Start with Model Driven Programmability and Management Levels

Topics in this chapter

Take them in order, or jump to the one you need.

  1. 1Model Driven Programmability and Management LevelsUnderstand why model driven programmability helps automation, and compare controller level management with device level…Diagram5 min
  2. 2Simulation, Test and Automation ToolsLearn what Cisco Modeling Labs and pyATS do for network simulation and testing, and compare the automation tools Ansible…5 min
  3. 3CI/CD for Infrastructure and Infrastructure as CodeLearn the parts and benefits of a CI/CD pipeline for infrastructure automation, plus infrastructure as code principles such as…Diagram5 min
  4. 4Identifying the Workflow in a Python API ScriptLearn to read a Python script that calls Cisco APIs on ACI, Meraki, Catalyst Center and RESTCONF, and identify the workflow it…5 min
  5. 5Interpreting an Ansible PlaybookRead an Ansible playbook and work out what it automates: packages, users, config files, services, variables, handlers and the…5 min
  6. 6Interpreting a Bash ScriptRead a Bash script and identify the workflow it automates, from variables, tests and loops to file handling, package installs…4 min
  7. 7Interpreting RESTCONF and NETCONF Results and YANG ModelsLearn to read RESTCONF and NETCONF replies and basic YANG models, including containers, lists, leaves, keys, types, config false…Diagram6 min
  8. 8Unified Diffs, Code Review and Sequence DiagramsLearn to read a unified diff, understand the principles and benefits of code review, and interpret a sequence diagram that shows…6 min

About this chapter

What this chapter covers

This chapter is about automating the network itself: the ideas, the tools and the skill of reading automation code.

You learn why model driven programmability matters, which tools build and test a network, and how infrastructure as code and CI/CD bring software discipline to operations. The second half is about interpretation. You read Python, Ansible, Bash, RESTCONF, YANG, diffs and sequence diagrams and say what they do.

Many exam questions in this chapter show you code and ask what it achieves.

How the topics fit together

The concepts explain why automation is built the way it is, and the reading skills let you check that it does the right thing.

ModelsYANG and APIsused byToolsCML, pyATS, Ansible, Terraform, NSOrun inPipelineGit, review, CI CDchangeNetworkdesired state

The first page compares controller level and device level management, and explains why models help both. The second page introduces the lab, test and automation tools. The third explains infrastructure as code and the CI/CD pipeline that applies it.

The remaining pages are reading practice. You identify the workflow in a Python API script, an Ansible playbook and a Bash script.

You read a RESTCONF or NETCONF reply against a YANG model. The last page covers diffs, code review and sequence diagrams, which are the ways teams review and explain a change.

Note

A pipeline ties it together. Code is reviewed in Git, checked with a diff, tested in a lab, and then applied by a tool such as Ansible.

How to use these pages

Each topic page has the same shape, so you can skim for what you need.

  • What it is: the idea in plain words.
  • How it works: the mechanism, with diagrams and short code examples.
  • What to remember for the exam: the facts to memorise.
  • Common mistakes: the classic traps.
  • Check yourself: three questions to test your understanding.

For the reading pages, cover the explanation after each sample and write one sentence that says what the code does. Then compare your sentence with the page.

That is the same skill the exam asks for. Practise with real playbooks and scripts, since you will meet the same patterns again and again.

Ready for more practice?

The full Cisco CCNA 200-901 DEVASC question bank has 808 questions, with timed practice exams and an explanation for every answer.

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