Cisco DEVASC 200-901: Complete DevNet Associate Certification Guide

The Cisco DevNet Associate (DEVASC 200-901) certification focuses on equipping professionals with foundational knowledge in software development, network automation, and Cisco platforms. The exam evaluates candidates on their ability to develop and maintain applications built on Cisco platforms. The goal is to bridge the gap between networking and software development, making it ideal for hybrid roles.

Exam Structure and Objectives

The DEVASC 200-901 exam covers six main areas: Software Development and Design, Network Fundamentals, Understanding and Using APIs, Cisco Platforms and Development, Infrastructure and Automation, and Application Deployment and Security. The structure of the exam is designed to evaluate both theoretical knowledge and practical application, ensuring a comprehensive understanding of modern networking principles.

Benefits of Earning the Certification

Achieving the DevNet Associate certification enhances your professional credibility and opens doors to new career opportunities. It demonstrates your capability to work with APIs, automate networks, and integrate software with Cisco solutions. The certification is increasingly valued in roles that combine software and networking, especially as networks become more programmable and API-driven.

Core Topics Covered in the Learning Path

This domain covers foundational software design principles, including version control, data formats like JSON and XML, and design patterns. Understanding these principles is crucial for anyone developing software solutions that integrate with network platforms.

Version Control Systems

Version control systems such as Git are critical tools for collaboration in software development. They help track changes, manage versions, and facilitate teamwork through branching and merging.

Data Formats

JSON and XML are standard formats used for data interchange in network programming. JSON is lightweight and easy to parse, while XML is more verbose but useful in certain structured data scenarios.

Programming Constructs

Familiarity with programming constructs like loops, conditionals, functions, and error handling is essential. These are foundational to writing efficient, maintainable, and robust scripts and applications.

Network Fundamentals

A solid understanding of network fundamentals is necessary to interact effectively with Cisco devices and technologies.

OSI and TCP/IP Models

The OSI and TCP/IP models are the frameworks that describe how data travels through a network. Knowing the layers and their functions aids in troubleshooting and designing networks.

IP Addressing and Subnetting

IP addressing, subnetting, and CIDR notation are foundational for understanding how networks are segmented and how devices communicate.

Common Protocols

Protocols such as HTTP, HTTPS, DNS, DHCP, and ICMP are vital for network operations. Understanding their roles and how they work ensures better network management and integration with applications.

API Usage and Integration

An Application Programming Interface (API) allows software applications to communicate with each other. In the networking world, APIs are used to control devices, gather data, and integrate services.

RESTful APIs

REST (Representational State Transfer) is a common architectural style used in network APIs. It uses standard HTTP methods like GET, POST, PUT, and DELETE, making it easy to use with tools like Postman and scripting languages like Python.

Consuming APIs

Learning to consume APIs involves sending requests to endpoints and parsing the responses. This is often done using Python libraries such as Requests or built-in modules like urllib.

Authentication and Authorization

Securing API access involves understanding methods like API keys, OAuth, and token-based authentication. Proper handling of credentials and secure storage are crucial for maintaining system integrity.

Cisco Platforms and Ecosystem

Cisco DNA Center

Cisco DNA Center offers a centralized management platform for enterprise networks. It provides APIs for automating configurations, collecting telemetry, and managing network policies.

Cisco Meraki

Cisco Meraki’s cloud-based dashboard provides APIs that allow users to manage devices, monitor usage, and automate administrative tasks. It is highly accessible and commonly used in small to medium-sized environments.

Cisco IOS XE

IOS XE is Cisco’s network operating system that supports modern automation interfaces like RESTCONF and NETCONF. Understanding these protocols and how to interact with them programmatically is a key skill in DevNet roles.

Webex and Collaboration APIs

Cisco’s collaboration tools, such as Webex, offer APIs to automate meeting scheduling, message sending, and user management. These capabilities are useful for integrating communications into custom workflows.

Practical Skills for Real-World Scenarios

Python is a preferred language in network automation due to its readability and extensive library support. Tasks such as device configuration, data retrieval, and log analysis can be easily automated with Python.

Using Ansible for Configuration Management

Ansible allows declarative configuration of network devices. It uses YAML files to define desired states and automates enforcement, making it a powerful tool for managing infrastructure.

Introduction to DevOps

DevOps involves integrating development and operations teams to enhance the software delivery process. In networking, it enables continuous integration and deployment (CI/CD) of network configurations and applications.

Preparing for the Certification Exam

A combination of video lectures, hands-on labs, and practice exams is recommended. Focus on understanding concepts, not just memorizing facts. Practical experience through simulations and real-world scenarios enhances retention.

Time Management

Creating a study schedule and sticking to it is essential. Break topics into manageable sections and allocate time for review and self-assessment.

Resources and Tools

Utilize Cisco’s DevNet Sandbox, packet tracers, virtual labs, and online forums to reinforce learning. These tools provide environments for experimentation and practice without risking production systems.

Infrastructure and Automation in Cisco Environments

Traditional network management has heavily relied on manual configuration and monitoring. However, with the increasing complexity and scale of networks, automation has become essential. Automating repetitive tasks reduces human error, enhances efficiency, and provides greater consistency across devices and services.

Infrastructure as Code (IaC)

Infrastructure as Code is the practice of managing and provisioning infrastructure through code instead of manual processes. It allows network configurations to be versioned, tested, and deployed consistently. Tools such as Ansible, Terraform, and Python scripts are commonly used to implement IaC in network environments.

Benefits of IaC

IaC provides improved scalability, reproducibility, and documentation. By treating infrastructure as code, teams can quickly roll out new environments, recover from failures, and track configuration changes over time.

Cisco-Specific Automation Tools

Cisco provides various platforms and tools to support network automation. These tools enable programmability and integration with existing infrastructure, making it easier to automate device configurations, monitoring, and troubleshooting.

Cisco DNA Center APIs

DNA Center exposes RESTful APIs for automating and integrating with network services. These APIs support a wide range of functions, including inventory management, device configuration, and telemetry collection.

Cisco Meraki Dashboard API

The Meraki Dashboard API allows for full control over Meraki devices and networks. With this API, administrators can configure SSIDs, monitor usage, and deploy updates across multiple locations.

Cisco NSO (Network Services Orchestrator)

Cisco NSO is a model-driven orchestration platform that automates the provisioning and lifecycle management of network services. It supports multivendor environments and provides high-level service abstraction for better management.

Automating with Python

Python is widely adopted for network automation due to its simplicity and rich ecosystem. Cisco offers Python libraries such as pyATS and Genie for automated testing and network verification.

Python and NETCONF/RESTCONF

NETCONF and RESTCONF are protocols that allow programmatic access to network device configurations. Using Python libraries like ncclient and requests, developers can interact with these protocols to retrieve and configure data.

Sample Automation Workflow

A common automation workflow might involve collecting interface statistics from multiple devices using RESTCONF, parsing the JSON data, and generating a summary report. With Python, this process can be encapsulated into scripts that run on demand or a schedule.

Automation Use Cases

Automation is useful in a variety of scenarios, including configuration management, monitoring, and compliance enforcement.

Device Configuration

Automating device configuration ensures that settings are applied consistently across all devices. This is especially useful in large environments where manual configuration would be time-consuming and error-prone.

Monitoring and Alerting

Automated systems can continuously monitor network health, usage, and performance. Alerts can be triggered when metrics exceed thresholds, enabling proactive maintenance.

Compliance and Auditing

Automation can enforce compliance with internal standards or industry regulations by periodically checking and remediating configurations. Scripts can generate audit reports and notify administrators of discrepancies.

Application Deployment and Security

Application deployment involves moving software from development to production environments. In the context of networking, this includes deploying applications that interact with network devices or services.

On-Premises Deployment

On-premises deployment refers to installing applications within the organization’s infrastructure. This model offers greater control but requires in-house maintenance and support.

Cloud Deployment

Cloud deployment leverages third-party platforms to host and manage applications. This model is scalable and reduces operational overhead, but it requires attention to data security and compliance.

Hybrid Deployment

A hybrid deployment combines on-premises and cloud models. It allows organizations to maintain control over critical components while leveraging the scalability of the cloud for others.

Continuous Integration and Continuous Deployment (CI/CD)

CI/CD is a set of practices that automate the building, testing, and deployment of applications. These practices enhance development efficiency and reduce the likelihood of introducing bugs into production.

Version Control Integration

CI/CD pipelines typically integrate with version control systems like Git to trigger builds when code is pushed. Automated testing and deployment ensure that only validated changes reach production.

Role of CI/CD in Network Automation

In networking, CI/CD pipelines can be used to deploy configuration changes, test automation scripts, and update firmware. This approach supports a DevOps mindset and promotes agility.

Application Security Fundamentals

Security is a critical consideration in application development and deployment. It includes protecting against threats, securing communications, and managing access control.

Common Security Threats

Applications may face threats such as SQL injection, cross-site scripting (XSS), and denial-of-service (DoS) attacks. Developers must validate inputs, sanitize outputs, and follow secure coding practices.

Secure API Communication

APIs should use HTTPS to encrypt data in transit. Authentication methods such as OAuth2 and API tokens help ensure that only authorized users can access endpoints.

Role-Based Access Control (RBAC)

RBAC restricts system access based on user roles. Implementing RBAC in applications and APIs ensures that users can perform only the actions permitted by their roles.

Real-World Scenarios and Use Cases

A practical use case of automation is creating VLANs across multiple switches. Instead of logging into each device, a script can read VLAN IDs from a file and configure them using SSH or RESTCONF.

Monitoring Network Health

Automated tools can continuously check the availability and performance of network components. For example, a Python script can ping key devices, log response times, and alert administrators of issues.

API-Driven Device Inventory

By integrating with Cisco DNA Center or Meraki Dashboard APIs, administrators can generate real-time inventory reports. These reports can include device models, firmware versions, and health status.

Auto-Remediation of Configuration Drift

Configuration drift occurs when devices deviate from the standard configuration. Automation can detect these changes and either report them or automatically restore the intended configuration.

Best Practices for Learning and Implementation

Start Small and Iterate

Begin with simple automation tasks such as gathering device information or backing up configurations. As you gain confidence, move to more complex scenarios involving policy enforcement and orchestration.

Use Version Control

Store all scripts and configurations in a version control system. This practice ensures that you can track changes, collaborate with others, and revert to previous versions if needed.

Build and Test in Lab Environments

Before applying changes to production, validate your scripts in a lab environment. This approach reduces the risk of disruptions and provides a safe space for experimentation.

Stay Informed and Up to Date

Network automation is a rapidly evolving field. Stay current with Cisco updates, open-source tool developments, and industry best practices to maintain relevance and efficiency.

Cisco Platforms and Development

Overview of Cisco Platforms

Cisco provides a range of platforms that cater to various networking needs, including enterprise, service provider, data center, and cloud environments. These platforms support programmability and automation through APIs, SDKs, and integration tools.

Cisco IOS XE

IOS XE is a network operating system that runs on Cisco enterprise networking devices. It supports programmability through model-driven telemetry, RESTCONF/NETCONF APIs, and Python scripting.

Cisco NX-OS

NX-OS is used in Cisco Nexus switches and provides high availability and scalability for data center networks. It also supports automation and scripting via Python, REST APIs, and NX-API.

Cisco Meraki

Meraki provides a cloud-managed platform for wireless, switching, security, and mobile device management. Its dashboard API enables full programmatic control over the network infrastructure.

Cisco DNA Center

DNA Center is a centralized management and automation platform for enterprise networks. It offers advanced capabilities such as AI-driven analytics, software-defined access, and comprehensive REST APIs.

Working with Cisco DevNet

Cisco DevNet is the developer program for Cisco. It provides tools, resources, and sandbox environments to help network engineers and developers create and test network automation scripts and applications.

DevNet Sandboxes

These are pre-configured, virtual environments that provide access to real Cisco devices and platforms for learning and testing. Sandboxes are available for DNA Center, Meraki, Webex, and more.

DevNet Learning Labs

These interactive labs cover topics such as Python programming, REST APIs, model-driven programmability, and automation with Ansible and Terraform.

DevNet Code Exchange

This is a repository of code samples, use cases, and tools shared by the community and Cisco engineers. It supports collaboration and the reuse of proven automation solutions.

Model-Driven Programmability

Model-driven programmability relies on structured data models like YANG to manage device configurations. Cisco platforms support YANG-based protocols such as NETCONF and RESTCONF.

YANG Data Modeling

YANG models describe the structure and constraints of configuration and operational data. They are vendor-neutral and can be extended to support new features.

gRPC and gNMI

Cisco devices increasingly support gRPC and gNMI for telemetry streaming. These protocols provide efficient, scalable methods for monitoring and analytics.

Integration with External Tools

Cisco platforms can integrate with various open-source and commercial tools to extend automation capabilities.

Ansible

Ansible uses playbooks to automate tasks across multiple devices. Cisco provides Ansible modules for IOS XE, NX-OS, and ASA platforms.

Terraform

Terraform is used for provisioning infrastructure across multiple cloud and on-prem environments. It can be extended with Cisco-specific providers for managing Meraki and cloud integrations.

Python Libraries

Python remains a popular choice for scripting. Libraries such as paramiko, requests, ncclient, and Genie enable developers to interact with network devices, APIs, and data streams.

Network Fundamentals for DevNet

OSI and TCP/IP Models

Understanding the OSI and TCP/IP models is essential for troubleshooting and designing network applications.

OSI Model Layers

The OSI model has seven layers: Physical, Data Link, Network, Transport, Session, Presentation, and Application. Each layer performs specific tasks and interacts with the layers above and below.

TCP/IP Model

The TCP/IP model simplifies the OSI model into four layers: Network Interface, Internet, Transport, and Application. It is the basis for the modern Internet.

IP Addressing and Subnetting

IP addresses identify devices on a network. Subnetting divides networks into smaller segments to improve performance and security.

IPv4 and IPv6

IPv4 uses 32-bit addresses, while IPv6 uses 128-bit addresses, providing a much larger address space. IPv6 also simplifies routing and supports enhanced features like auto-configuration.

Subnet Masks and CIDR

Subnet masks define network boundaries. Classless Inter-Domain Routing (CIDR) allows for more efficient IP address allocation.

Network Protocols

Key network protocols include:

• HTTP/HTTPS: Web traffic

• DNS: Domain resolution

• DHCP: Dynamic IP addressing

• ARP: MAC address resolution

• ICMP: Ping and diagnostics

Understanding these protocols is crucial for developing and troubleshooting network-aware applications.

Routing and Switching Basics

Routing directs traffic between networks, while switching connects devices within a local network.

Static vs Dynamic Routing

Static routes are manually configured. Dynamic routing uses protocols like OSPF and EIGRP to automatically adjust routes based on network conditions.

VLANs and Trunking

VLANs separate traffic for better security and performance. Trunk ports carry multiple VLANs between switches.

APIs in Network Automation

What is an API

An API (Application Programming Interface) allows software components to communicate. In networking, APIs provide programmable access to device functions and data.

REST APIs

REST (Representational State Transfer) is a popular web API architecture that uses standard HTTP methods. REST APIs are stateless and use JSON or XML for data exchange.

RESTCONF and NETCONF

These are network-focused APIs that use YANG models. RESTCONF uses HTTP, while NETCONF uses XML over SSH. Both allow configuration and retrieval of device data.

API Authentication

APIs use various methods to ensure that only authorized users can access them.

Token-Based Authentication

Tokens such as API keys or OAuth2 tokens identify and authorize users. Tokens are typically passed in the HTTP header.

Basic and Digest Authentication

These methods involve sending usernames and passwords with each request. They are simpler but less secure if not used over HTTPS.

Using Postman and Curl

Postman is a graphical interface for testing APIs. Curl is a command-line tool. Both can send requests, receive responses, and debug issues.

Building and Using APIs

Developers can build APIs using frameworks like Flask or Django in Python. This is useful for creating custom services that interact with network data or external applications.

Practical Labs and Exercises

Hands-On with REST APIs

A basic lab could involve querying Cisco DNA Center for device inventory. Using Postman, send a GET request to the API endpoint and examine the JSON response.

Automating Configuration with Ansible

Write an Ansible playbook to configure multiple routers with a hostname and interface IPs. Use the ios_config module to apply changes.

Parsing JSON with Python

Fetch device data via an API, parse the JSON using Python’s json module, and extract key information such as uptime or interface status.

Creating Custom Dashboards

Use Flask and Chart.js to build a dashboard that visualizes network metrics pulled from Cisco APIs. Host it locally for demo purposes.

Continuous Practice and Testing

Repeat labs with different parameters. Test scripts in sandbox environments to build confidence before applying them in production.

Application Deployment and Security

Application deployment involves moving software from development to a live environment. It includes steps such as compiling code, testing, packaging, configuring environments, and launching applications in production.

Deployment Models

Modern application deployment supports several models, including:

• On-premises: Traditional servers are managed in a physical data center.

• Cloud: Applications deployed on platforms like AWS, Azure, or Google Cloud.

• Hybrid: A mix of on-prem and cloud infrastructure.

• Edge: Running applications closer to the source of data or end-users.

Application Environments

Applications move through various environments during development:

• Development: Initial coding and unit testing.

• Staging: A near-production environment for integration testing.

• Production: The live environment where end-users interact with the application.

CI/CD Pipelines

Continuous Integration and Continuous Deployment (CI/CD) automate testing and deployment processes to ensure fast and reliable software releases.

Tools for CI/CD

• Jenkins: Widely used for pipeline automation.

• GitLab CI/CD: Integrated with source control for streamlined workflows.

• GitHub Actions: Event-driven automation based on GitHub events.

Steps in a Pipeline

• Code pushed to the repository

• Automated build starts

• Unit and integration tests run.

• Artifacts created

• Deployment to staging

• Final approval triggers production deployment.

Containerization with Docker

Containers package applications and their dependencies into isolated environments, ensuring consistent behavior across systems.

Benefits of Docker

• Portability: Run containers on any platform

• Isolation: Avoid conflicts between applications

• Efficiency: Lightweight compared to virtual machines

Docker Components

• Dockerfile: Instructions for building a container image

• Image: A snapshot of an application

• Container: A running instance of an image

• Registry: A storage location for images (e.g., Docker Hub)

Orchestration with Kubernetes

Kubernetes automates the deployment, scaling, and management of containerized applications. It organizes containers into pods and manages their lifecycle.

Key Concepts

• Pod: A group of containers

• Node: A virtual or physical machine that runs pods

• Cluster: A group of nodes managed by Kubernetes

• Deployment: Defines the desired state of an application

Security in Application Development

Securing applications involves protecting code, data, communications, and user access. It must be integrated throughout the development lifecycle.

Common Threats

• Injection attacks (SQL, command)

• Cross-site scripting (XSS)

• Cross-site request forgery (CSRF)

• Insecure deserialization

• Broken authentication

Secure Coding Practices

• Input validation: Sanitize user input to prevent injection

• Authentication and authorization: Use multi-factor authentication and role-based access

• Secure dependencies: Keep libraries and frameworks updated

• Error handling: Avoid exposing sensitive information in logs or error messages

Encryption and Secure Communications

Data should be encrypted both in transit and at rest.

TLS/SSL

Use Transport Layer Security (TLS) to encrypt communications between clients and servers.

SSH

Secure Shell (SSH) enables encrypted remote administration and file transfers.

Identity and Access Management (IAM)

IAM defines and manages user roles and permissions across systems.

Principles of IAM

• Least privilege: Grant minimum access required

• Role-based access control (RBAC): Assign permissions based on roles

• Authentication: Verify user identity

• Authorization: Determine access rights

Monitoring and Logging

Tracking system events and metrics helps detect anomalies, audit access, and troubleshoot issues.

Tools for Monitoring

• Prometheus: Collects metrics

• Grafana: Visualizes data

• ELK Stack (Elasticsearch, Logstash, Kibana): Centralized logging

Secure API Usage

APIs must be protected against abuse and unauthorized access.

Rate Limiting

Limit the number of API requests per user to prevent abuse.

Token Expiration

Use tokens with limited lifetimes to reduce the impact of compromised credentials.

Input Validation

Validate all incoming data to prevent injection and overflow attacks.

Cisco-Specific Security Features

Cisco Umbrella

A cloud-delivered security platform that blocks threats at the DNS level.

Cisco ISE (Identity Services Engine)

Provides policy-based access control for users and devices.

Cisco SecureX

An integrated security platform that unifies visibility, automation, and response across Cisco and third-party tools.

Application Security Testing

Security testing is performed throughout development to find and fix vulnerabilities early.

Static Application Security Testing (SAST)

Analyzes source code for vulnerabilities without executing the application.

Dynamic Application Security Testing (DAST)

Tests a running application to identify security flaws.

Interactive Application Security Testing (IAST)

Combines aspects of SAST and DAST for real-time feedback during testing.

Automating Security Processes

Security can be integrated into CI/CD pipelines through automation:

• Code scanning tools run during commits

• Secret detection tools check for hardcoded credentials.

• Container scanning tools check for vulnerabilities in images.

Compliance and Regulations

Applications must comply with regulations such as:

• GDPR (General Data Protection Regulation)

• HIPAA (Health Insurance Portability and Accountability Act)

• PCI-DSS (Payment Card Industry Data Security Standard)

Ensure systems are auditable and data privacy requirements are met.

DevOps in Networking

DevOps is a culture and set of practices that bridge software development and IT operations. It aims to shorten the development lifecycle and deliver high-quality software reliably.

DevOps Principles

• Automation: Reduce manual processes

• Collaboration: Break down silos between teams

• Continuous improvement: Iterate rapidly

• Measurement: Track performance and usage metrics

Infrastructure as Code (IaC)

IaC allows infrastructure to be defined and managed using code. This ensures consistency and enables version control.

Tools for IaC

• Ansible: Automates configuration management

• Terraform: Provision infrastructure resources

• Puppet/Chef: Manages infrastructure lifecycle

Network as Code

Extending IaC principles to networking involves automating the configuration, management, and monitoring of network devices using code.

Benefits of Network Automation

• Reduced human error

• Faster deployment

• Improved consistency

• Easier compliance audits

DevOps Tools for Network Engineers

Version Control with Git

Track and manage changes in configuration files using repositories like GitHub or GitLab.

CI/CD for Network Configurations

Automate testing and deployment of network changes using CI/CD pipelines. Integrate with tools like Jenkins or GitHub Actions.

Monitoring and Telemetry

Use model-driven telemetry, SNMP, and NetFlow to gather network metrics and automate alerts.

Change Management in DevOps

DevOps emphasizes fast, safe change deployment. Version-controlled, peer-reviewed code allows safe rollback and auditability.

Strategies for Change Control

• Feature toggles

• Canary deployments

• Blue-green deployments

Collaboration and Documentation

DevOps encourages documentation through code comments, README files, and wikis. Collaboration tools like Slack, Jira, and Confluence enhance team communication.

Final Thoughts

The Cisco DevNet Associate (DEVASC 200-901) learning path is more than a certification prep guide, it’s a bridge to a new generation of network engineering. Through the structured, example-rich, and hands-on content covered across all four parts, this learning path empowers learners to transition from traditional networking roles into hybrid positions that blend programming, automation, and platform integration.

Whether you are a network engineer taking your first steps into the software domain, an automation engineer optimizing Cisco environments, or a junior developer learning infrastructure dynamics, this path has given you the foundations needed to design, develop, and deploy modern network solutions.

By mastering topics like APIs, Infrastructure as Code, CI/CD, containerization, and network programmability, you’re positioned to help lead the evolution toward intent-based and automated networks. The demand for professionals who understand both software and network engineering will only grow as organizations increasingly rely on agile, programmable infrastructures.

Continue practicing in lab environments, stay up to date with Cisco DevNet resources, and build projects that solve real problems. The DEVASC 200-901 certification is just the beginning of a career that merges code and connectivity, built for the networks of tomorrow.