Cisco 200-901 DevNet Associate (DEVASC) Exam Practice Test

The docker run command is used to create and start a new container from an image. The -p option maps a port on the host to a port in the container.

Port Mapping: The syntax -p [host_ip:host_port:container_port/protocol] is used to map ports.

Exposing Port 8443: The correct mapping to expose the API on port 8443 and allow external connections is 0.0.0.0:443:8443/tcp, which maps port 443 on the host to port 8443 in the container.

Option B correctly maps the ports and allows external connections.

pyATS (Python Automation Test System) is a tool developed by Cisco that allows for comprehensive testing of network configurations and automation scripts. It is designed to validate and test changes before they are applied to the production environment, ensuring reliability and reducing the risk of errors.

References:

Cisco DevNet Associate Study Guide: Network Test Automation (Chapter 6, Section: Introduction to pyATS and Its Use Cases).

In the provided cURL command, the developer needs to include an authorization header with the access token to authenticate the API request. Without proper authentication, the server will reject the request and return an error code.

To ensure that changes in a file that already exists in a local repository are included in the next Git commit, the git add command must be executed. This command stages the changes in the specified file(s) so they will be included in the next commit.

A. git update - Incorrect. There is no git update command. B. git merge - Incorrect. This command is used to merge branches, not to stage changes. C. git add - Correct. This command stages changes in the working directory to be included in the next commit. D. git rebase - Incorrect. This command is used to reapply commits on top of another base tip.

References:

Git Basics - Recording Changes to the Repository

Simulation Environment: CML provides a realistic environment for testing network configurations and automation scripts before deploying them on actual devices.

Resource Verification: Engineers can use CML to ensure that their Ansible playbooks function correctly and make necessary adjustments before running the code in a live network.

Option D is the correct resource for verifying the code using a simulated network environment.

The agile process allows for incremental delivery of features, meaning new functionalities can be added or existing ones updated in small, manageable increments. This is in contrast to the waterfall model, where all phases are completed before the product is delivered. Agile enables continuous improvement and adaptation to changing requirements throughout the development process.

The DevNet Automation Exchange is designed to provide users with easy-to-consume use cases for network automation across various skill levels. It includes resources for beginner, intermediate, and advanced users to help them accelerate the adoption of automation technologies.

DevNet Automation Exchange: This site provides curated content and solutions for network automation. It includes code samples, learning labs, and use cases that cater to different skill levels.

User-Friendly Resources: The platform is designed to help users find relevant information quickly and easily, regardless of their experience level.

Option B is the correct answer because it specifically addresses the need for a single site that offers a variety of resources for different skill levels in network automation.

A containerized application environment meets the requirements of being hardware-independent and allows for the installation and management of the environment to be fully automated. Containers package the application and its dependencies together, ensuring consistency across different environments. This method is also highly compatible with automation tools and orchestrators like Kubernetes, making deployment and management easier and more efficient.

References:

Cisco DevNet Associate Study Guide: Understanding Application Deployment (Chapter 4, Section: Containers and Their Benefits).

Load balancers distribute network or application traffic across multiple servers to ensure no single server becomes overwhelmed. In modern application deployment, load balancers allow traffic to continue smoothly as new compute units are brought online and old units are decommissioned. This ensures high availability and reliability of services.

In the provided Python function enable_function, the parameters are if_name, if_status, and if_type, which correspond to the interface name, status (enabled/disabled), and interface type respectively.

Function Parameters: The function enable_function is designed to take three parameters: the interface name (if_name), the status (if_status), and the type (if_type).

Correct Order and Values: To enable the interface named "Loopback1", you need to pass the correct values in the order they are defined in the function.

Option A correctly calls the function with the interface name "Loopback1", the status true (enabled), and the interface type 'iana-if-type:softwareLoopback'.

In the Ansible playbook, the last task uses the apt module with state: absent and purge: yes for the webexbot package. This configuration ensures that the package is uninstalled and all associated configuration files are removed. This is different from a simple uninstall, which would leave configuration files behind.

References:

Cisco DevNet Associate Study Guide: Automation with Ansible (Chapter 7, Section: Ansible Playbook Examples and Syntax).

The HTTP response code 204 No Content indicates that the server successfully processed the request, but there is no content to send in the response. This status code is typically used when a request is successfully handled, but no additional information needs to be returned to the client.

References:

Cisco DevNet Associate Study Guide: HTTP Status Codes (Chapter 7, Section: Common HTTP Response Codes).

One of the primary benefits of test-driven development (TDD) is increased code quality. By writing tests before coding and continuously testing during development, developers ensure that the code meets the specified requirements and behaves as expected. This approach leads to more reliable, maintainable, and bug-free code.

In the provided network topology, Device E is positioned between Server 1 and Server 2. Device E, being a Layer 2 switch, will limit traffic between these servers by making forwarding decisions based on MAC addresses. If there are VLANs configured, Device E will ensure that traffic is segregated accordingly, allowing only specific traffic to pass between the servers as defined by the network policies.

References:

Cisco DevNet Associate Study Guide: Network Components (Chapter 2, Section: Switches and Their Role in Network Traffic Management).

Cisco Finesse offers several capabilities:

Browser Access: Agents can access Finesse directly from a browser, eliminating the need for any client-side installation or configuration. This simplifies deployment and maintenance.

Gadget Containers: Finesse provides a single user interface that integrates multiple gadget containers, allowing for a seamless and unified experience.

The main purpose of a code review is to identify and review errors, ensuring code quality and adherence to coding standards. It involves evaluating the code for bugs, security vulnerabilities, and performance issues, and discussing potential improvements with the team. This collaborative process helps catch errors early, fosters knowledge sharing, and improves the overall quality of the codebase.

References:

Cisco DevNet Associate Study Guide: Code Review Best Practices (Chapter 6, Section: Importance of Code Reviews).

Model-driven programmability leverages models to represent the desired state of network configurations, allowing for programmatic and standards-based management. This approach ensures that configurations can be written consistently and automatically across different network devices, simplifying network management and reducing the risk of configuration errors.

References:

Cisco DevNet Associate Study Guide: Model-Driven Programmability (Chapter 5, Section: Benefits of Model-Driven Programmability).

In the given network topology, the load balancer's primary role is to distribute incoming requests to the application servers. This ensures that no single server is overwhelmed, and it helps in providing high availability and reliability for the hosted applications.

RESTCONF and YANG are used for network configuration and management on Cisco IOS XE devices. RESTCONF provides a REST-like interface for accessing YANG-defined data models, allowing engineers to change configurations such as netmasks through programmable interfaces.

References:

Cisco DevNet Associate Study Guide: Network Programmability and Automation (Chapter 6, Section: Using RESTCONF and YANG).

When selecting the "best route" for a network device to reach its destination, the considerations include:

Metrics: These are values used by routing protocols to determine the best path to a destination. Metrics can include factors like hop count, bandwidth, delay, load, and reliability.

Administrative Distance: This is a value used to rate the trustworthiness of the source of the routing information. Lower values indicate more trusted routes.

To create and switch to a new branch called "my-bug-fix" in Git, you use the git checkout -b command. This command creates the branch and switches to it in one step.

A. git checkout -b my-bug-fix - Correct. This command creates a new branch and switches to it. B. git branch -b my-bug-fix - Incorrect. The -b option is not valid with git branch. C. git branch my-bug-fix - This creates a new branch but does not switch to it. D. git checkout my-bug-fix - This switches to an existing branch but does not create a new one.

References:

Git Branching - Creating a Branch

Private IP addresses are used within private networks and are not unique globally. They can be reused in different private networks without conflict.

Non-unique Addresses: Private IP addresses do not have to be unique globally, allowing them to be reused in different networks.

Repetition in Local Networks: They can be repeated within different local networks as they are not routable on the public Internet.

Options C and D correctly describe properties of private IP addresses.

JSON and XML are both used for data interchange, but they have differences in functionality:

JSON: JavaScript Object Notation natively supports arrays and other data structures like objects (dictionaries in Python). JSON is known for being lightweight and easy to parse and is often considered more human-readable due to its simple syntax.

XML: eXtensible Markup Language does not natively support arrays in the same straightforward manner as JSON. Instead, arrays in XML need to be represented using repeated elements, which can be more verbose and complex. XML is highly flexible and supports defining custom tags, but it is generally more complex and less human-readable compared to JSON.

Therefore, JSON's native support for arrays makes it simpler and more efficient for certain data structures compared to XML.

The 401 Unauthorized status code indicates that the request lacks valid authentication credentials. When using OAuth2 for authenticating with the Cisco Webex API, the correct approach is to include a Bearer token in the Authorization header.

header = {"Authorization": "Bearer YOUR_TOKEN"}

This option correctly formats the Authorization header, which is necessary for the Webex API to authenticate the request. The Bearer token is a type of token used by OAuth2 to access protected resources.

Authorization Header: The header must contain the key "Authorization" with the value formatted as "Bearer YOUR_TOKEN".

Bearer Token: The Bearer keyword followed by a space and the token itself is the correct way to pass the OAuth2 token in the header.

Option B:

Incorrect because it uses "Authentication" instead of "Authorization".

Option C:

Incorrect because it combines Authentication and Bearer incorrectly without a space.

Option D:

Incorrect for the same reason as Option C.

References:

Cisco Webex API Authentication

OAuth2 Authorization Header =====================

A developer is creating a script to interact with a REST API service that requires basic authentication. The correct combination of payload and headers using Basic Authentication with the provided Base64 encoded credentials is:

A. This option does not use headers correctly. B. Option B - Correct. This option correctly places the 'Authorization' header in the headers dictionary with 'Basic' authentication. C. This option uses 'Bearer' instead of 'Basic' for the 'Authorization' header. D. This option uses 'Bearer' instead of 'Basic' for the 'Authorization' header.

References:

HTTP Authentication

Base64 Encoding

The Python script shown in the exhibit collects CLI arguments, organizes data according to the Cisco-IOS-XE-native YANG model, and utilizes Cisco REST APIs to make configuration changes. The workflow being automated by the script is adding a new route to a device.

A. updating an existing route on the device - Incorrect. The script is adding a new route, not updating an existing one. B. adding a new route to a device - Correct. The script adds a new route using the provided prefix, mask, and IP address. C. including a route on the device and overwriting the current routes - Incorrect. The script does not indicate it overwrites existing routes. D. deleting the route that is passed through the command-line variables - Incorrect. The script is adding a route, not deleting one.

References:

Cisco IOS XE YANG Data Models

Cisco REST API Documentation

To integrate changes from an existing branch named 'feat00304' into a single commit with the current working primary branch 'prodapp411926287', the git merge --squash command must be used. This command squashes all commits from the feature branch into a single commit before merging.

A. git rebase --merge feat00304 - Incorrect. This command does not perform a squash merge. B. git merge --squash feat00304 - Correct. This command squashes all commits from 'feat00304' into a single commit and then merges it. C. git push --rebase feat00304 - Incorrect. This command is used for pushing changes and rebasing, not for squashing commits. D. git checkout --squash feat00304 - Incorrect. This command is invalid.

References:

Git Merge Squash

The Python script uses nested loops to gather information:

The first loop checks for the "ACME" organization.

If found, it collects information about the networks in that organization.

The second loop checks for the "BLDG21" network.

If found, it gathers information about clients in that network.

This process effectively provides the BLDG21 network information if it is part of the ACME organization.

The exhibit illustrates a Continuous Integration/Continuous Deployment (CI/CD) pipeline. This method involves continuous integration of code from multiple developers, automated testing, and continuous delivery/deployment to production. It ensures that code changes are automatically built, tested, and deployed, promoting efficient and reliable software development practices.

The task is to determine which command correctly outputs the page_id value from the JSON payload shown in the Python 3.7 script. Let’s analyze the options and the payload structure to verify the correct answer.

JSON Payload Analysis:

The JSON payload provided in the exhibit shows that items is a key in the top-level dictionary.

The value of items is a list of dictionaries, and each dictionary contains various keys, including page_id.

Code Analysis:

The JSON data returned by the get_json function is assigned to the variable items.

The goal is to access the page_id key within the first dictionary of the list associated with the items key.

Options Analysis:

Option A: print(items['items']['page_id'])

This will not work because items['items'] is a list, not a dictionary. Attempting to access ['page_id'] directly from a list will result in a TypeError.

Option B: print(items.get('items').get('page_id'))

This will also not work for the same reason as Option A. items.get('items') returns a list, and calling .get('page_id') on a list is invalid.

Option C: print(items.get('items')[0].get('page_id'))

This is correct. items.get('items') returns the list, [0] accesses the first element of the list (which is a dictionary), and .get('page_id') retrieves the value of the page_id key from that dictionary.

Option D: print(items['items']['page_id'].keys())

This will fail because items['items'] is a list and does not have a keys() method.

Correct Explanation:

The JSON structure contains a list under the key items.

To access page_id, we first need to get the first dictionary in this list ([0]).

We then access the page_id key in this dictionary.

Example:

print(items.get('items')[0].get('page_id'))

This code correctly navigates through the structure and retrieves the value associated with page_id.

References:

Python Documentation on Dictionaries: Python Docs

JSON Data Handling in Python: Python JSON

A model-driven approach for infrastructure automation offers several benefits. One of the primary advantages is that it provides a small learning curve and helps system administrators with limited coding experience. By using high-level models and declarative languages, administrators can define the desired state of the infrastructure without needing to write complex scripts.

Declarative Language: Model-driven approaches use declarative languages that allow users to specify what the desired state should be, rather than how to achieve that state. This abstracts the complexity of the underlying automation processes.

References: Cisco DevNet Associate Certification Guide, Chapter on Infrastructure as Code and Model-Driven Programmability.

Ansible is a configuration management tool that has agentless capabilities. It uses SSH for communication and does not require any agent software to be installed on the managed nodes. This simplifies management and reduces overhead.

Cisco DNA Center is a comprehensive network management and command center for enterprise networks, providing centralized management, automation, security, and policy enforcement across both wired and wireless networks.

Cisco ACI: Primarily focuses on data center automation and policy enforcement.

Cisco DNA Center: Provides organization-wide automation, security, and policy enforcement capabilities for both wired and wireless networks.

Cisco Umbrella: Offers cloud security services.

Cisco SD-WAN: Focuses on software-defined wide-area networking solutions.

Cisco DNA Center is designed to bring agility and operational efficiency across the entire enterprise network by leveraging advanced automation and assurance capabilities.

Agentless configuration management systems, such as Ansible, do not require agents to be installed on the managed hosts. Instead, they leverage existing protocols and services to perform configuration tasks.

Agentless Approach: These systems rely on protocols like SSH (for Unix/Linux) or WinRM (for Windows) to communicate with and manage the hosts.

No Agent Installation: Managed hosts do not need any additional software (agents) installed, which simplifies management and reduces overhead.

Interpreters: They may require the managed hosts to have an interpreter for scripts (e.g., Python) but primarily use existing network protocols for communication.

Option D correctly identifies that agentless configuration management systems use existing protocols to interface with managed hosts.

To ensure the Python code runs successfully, the environment variable WEBEX_TEAMS_ACCESS_TOKEN must be set. This can be done using the export command in a Bash script.

A. define WEBEX_TEAMS_ACCESS_TOKEN=your_access_token_here - Incorrect. define is not a valid Bash command for setting environment variables. B. export WEBEX_TEAMS_ACCESS_TOKEN=your_access_token_here - Correct. This command correctly sets the environment variable for the current session. C. set WEBEX_TEAMS_ACCESS_TOKEN=your_access_token_here - Incorrect. set is not used in this context for setting environment variables in Bash. D. WEBEX_TEAMS_ACCESS_TOKEN=your_access_token_here - Incorrect. This command sets the variable but does not export it to be available to child processes.

References:

Setting Environment Variables in Bash

Model-driven programmability offers several benefits:

Model-driven APIs for abstraction and simplification: These APIs provide a higher level of abstraction, making it easier to manage and automate networks.

Models decoupled from transport, protocol, and encoding: This decoupling ensures that the same model can be used with different transport protocols, making the system more flexible and easier to integrate with various technologies.

The Cisco DevNet API documentation is the primary resource for understanding the meanings of response codes received from REST API calls. It provides comprehensive details about the API endpoints, response codes, and their interpretations, which helps developers troubleshoot and understand the responses they receive.

When an application interacts with a webhook, it is typically characterized as a "listener" or "receiver." A webhook is a way for an application to provide real-time data to other applications as events occur. The listener or receiver application waits for incoming HTTP requests (events) triggered by certain activities on another application, making it possible to process the data immediately upon receipt.

References:

Cisco DevNet Associate Study Guide: Event-Driven Programming (Chapter 8, Section: Understanding Webhooks and Their Applications).

The bash script shown in the exhibit automates the process of downloading, extracting, compiling, installing, and configuring the Cisco DevNet application. It also enables and starts the application automatically.

Download and Extract: The script uses curl to download a tar.gz file and then extracts it using tar -zxf.

Compilation and Installation: The ./configure && make && make install commands compile and install the application.

Enabling and Starting the Service: The systemctl enable devnet and systemctl start devnet commands ensure the application starts automatically on system boot and starts it immediately.

Option B correctly describes the workflow as it includes compilation, installation, configuration, and automatic startup of the application.

The Python script in the exhibit interacts with Cisco DNA Center APIs to query devices and execute commands. It collects the results of specific show commands from the devices.

Device Query: The script first queries for devices with the platformId of 'C9500-40X'.

Command Execution: It sends commands (show version, show ip int brief) to these devices.

Result Gathering: The script retrieves and processes the results of the executed commands.

Option A accurately describes the process automated by the script, which is to gather the results of the show version and show ip int brief commands.

Ansible is a powerful automation tool used for IT tasks such as configuration management, application deployment, and task automation. In the context of the exhibit, Ansible can be used to automate the removal of a Cisco Meraki device from the network and retrieve device information.

Device Management: Ansible modules, such as the meraki_device module shown in the exhibit, allow for the management of Meraki devices. Tasks can include querying device information and changing the state of the device.

Automation with Playbooks: The Ansible playbook in the exhibit demonstrates how to authenticate, define the organization and network, and manage the device state (query or absent).

Task Execution: The playbook is structured to perform tasks using a loop (with_items) to execute actions such as querying device details and removing the device (absent state).

References:

Ansible Documentation for Meraki Modules: Ansible Meraki Modules

Network Time Protocol (NTP) is used to synchronize the clocks of network devices to a common reference time. This is crucial for ensuring accurate time stamps in logs, coordinating time-sensitive operations, and maintaining consistent time across all devices in a network.

NTP: Synchronizes clocks of network devices to ensure they have the same time, which is essential for accurate event logging and coordination.

Other Protocols:

DNS: Resolves domain names to IP addresses.

SNMP: Used for monitoring network devices.

NAT: Translates private IP addresses to public IP addresses.

References:

Cisco DevNet Associate Certification Guide

Cisco NTP Overview

The control plane in a network device is responsible for routing and signaling. Protocols such as BGP (Border Gateway Protocol) and OSPF (Open Shortest Path First) are integral to the control plane.

BGP (Border Gateway Protocol): BGP is used for exchanging routing information between autonomous systems on the internet, making it a crucial control plane protocol.

OSPF (Open Shortest Path First): OSPF is an interior gateway protocol used for routing within an autonomous system, also part of the control plane.

References:

BGP and OSPF Protocol Details: BGP, OSPF

loads() function is present in python built-in 'json' module. This function is used to parse the JSON string.

The diff command is used to compare the contents of two files and display the differences. The -u option stands for "unified" and shows the differences in a unified format, which includes the lines that differ between the two files along with a few lines of context.

When running the command diff -u file1.txt file2.txt, it compares the two files and shows the differences between them.

References:

GNU Diffutils: Unified Format

The Python script shown in the exhibit is designed to interact with Cisco DNA Center APIs. Here's a step-by-step breakdown of what the script does:

It imports necessary libraries and sets the BASE_URL, AUTH_URL, and TOKEN for authentication.

It defines the headers to include the authentication token and content type.

It constructs URLs for fetching the device count, all devices, and devices by ID.

The devices_func function makes a GET request to fetch the total count of devices.

The devices_test function fetches a list of network devices based on query parameters.

The devices_info function retrieves detailed information about a specific device using its ID.

The script then prints the total count of devices, all devices, and filtered device information based on the hostname and platform ID.

In the final step, after executing the script, it fetches devices with the hostname "CSR1Kv-01.devnet.local" and then filters the list by platform ID "C9500-40X". This results in displaying the filtered information about the device that matches both the hostname and platform ID criteria.

References:

Cisco DevNet Associate Certification Guide

Cisco DNA Center API Documentation

The provided diff format shows changes between two versions of a file. The + signs indicate lines that have been added in the new file (new.py). The code snippet that belongs to the new file is the one with + signs, showing the addition of code to print the device list filtered by hostname. The added lines include printing the message and setting the query_string_params to filter by hostname.

Test-Driven Development (TDD) is a software development approach where tests are written before writing the actual code. TDD enables and encourages code refactoring because it ensures that tests are already in place to verify the correctness of the code after changes.

Red-Green-Refactor Cycle: TDD follows a cycle of writing a test (Red), writing code to pass the test (Green), and then refactoring the code while ensuring the test still passes (Refactor).

Refactoring Support: Because tests are written first, developers can confidently refactor code knowing that any changes that break functionality will be caught by the existing tests.

References:

Test-Driven Development: TDD Overview

Deploying applications in a public cloud provides several advantages, especially for developers dealing with temporary data processing and secure storage:

Ease in Infrastructure Management: Public cloud services offer managed infrastructure, which significantly reduces the operational burden on developers. They do not need to worry about hardware maintenance, scaling, or other infrastructure-related tasks.

Scalability: Public clouds provide scalable resources, allowing developers to adjust their infrastructure needs dynamically as per the workload requirements.

Cost-Effectiveness: Public clouds often operate on a pay-as-you-go model, which can be more cost-effective for temporary or variable workloads.

References:

Cisco DevNet Associate Certification Guide

General public cloud service provider documentation (e.g., AWS, Azure, Google Cloud)

To download and execute an Apache web server container in Docker, you need to perform two steps: pulling the image and running the container with the appropriate port bindings.

docker pull httpd - This command downloads the Apache HTTP server image from the Docker repository. "httpd" is the official name for the Apache HTTP server image on Docker Hub.

docker run -p 8080:80 httpd - This command runs a new container from the "httpd" image, mapping port 8080 on the host to port 80 in the container. This allows you to access the web server running in the container via port 8080 on your host machine.

References:

Docker Documentation - docker pull

Docker Documentation - docker run

Cisco DevNet Associate Certification Guide

RFC 5988 defines Web Linking, which provides a framework for indicating the relationships between resources on the web. In this context, the Link header in the HTTP response specifies the URL for the next set of results (pagination). The rel="next" attribute indicates that the provided URL should be used to fetch the next page of results, allowing the API to handle large datasets by breaking them into smaller, manageable chunks.

HTTP status codes in the 300 range are related to redirection. These codes indicate that the requested resource has been moved to a different URL, and the client should use the new URL provided in the response. Common examples include 301 (Moved Permanently) and 302 (Found).

Cisco Webex offers a range of collaboration capabilities, including real-time messaging, video conferencing, and integration with various productivity tools. Specifically, Webex allows users to:

Get Space History: Users can retrieve historical messages and files shared within a space, ensuring they have access to all past communications and documents.

Real-Time Notifications: Webex provides notifications when new messages are posted in spaces, allowing users to stay updated with ongoing conversations and respond promptly.

These features enhance the collaborative experience by ensuring users can keep track of conversations and receive timely updates.

References:

Cisco Webex Features

The git clean -n command is used to show which files would be removed from the working directory. It displays the untracked files that would be deleted, without actually removing them. This allows the developer to review the list of untracked files before taking any action, ensuring no important files are accidentally deleted.

References:

Git Documentation - git clean

Cisco DevNet Associate Certification Guide

Agile:

Optimization of the development process

Focused on the processes of a specific team

Lean:

Optimization of the production process

Focused on the processes of an organization

Agile Methodology:

Optimization of the Development Process: Agile focuses on improving and optimizing the software development process through iterative and incremental development, continuous feedback, and adapting to changes quickly.

Focused on the Processes of a Specific Team: Agile practices are typically implemented within specific development teams, emphasizing collaboration, flexibility, and team autonomy.

Lean Methodology:

Optimization of the Production Process: Lean aims to streamline the production process by eliminating waste, improving efficiency, and delivering value to the customer with the least amount of resources.

Focused on the Processes of an Organization: Lean principles can be applied across the entire organization, not just within individual teams, to improve overall processes and workflow efficiency.

References:

Cisco DevNet Associate Certification Guide, Sections on Agile and Lean methodologies

Official documentation and resources on Agile and Lean software development practices

"The Lean Startup" by Eric Ries (for Lean principles)

"Agile Software Development with Scrum" by Ken Schwaber and Mike Beedle (for Agile principles)

Therefore, the correct mapping is:

Agile:

Optimization of the development process

Focused on the processes of a specific team

Lean:

Optimization of the production process

Focused on the processes of an organization

Telnet is a network protocol that allows a user to communicate with a remote device or server. The default TCP port used by Telnet is port 23. This port is standardized and commonly used for Telnet connections to access network devices for administrative purposes.

The packet capture shows that the packets are arriving at Server B and that the server responds, indicating that Server B is reachable and the API service is running. However, since the developer cannot access the API, the most likely cause is that the return traffic on port 443 (HTTPS) is being blocked on the incoming interface of Firewall B. This means that although Server B is responding, the responses are not getting back to the developer's client because they are being blocked by the firewall.

The block of code that correctly completes the script should handle timeout exceptions and print the error, as well as print the response body if the HTTP status code is 200. Option A achieves this:

import requests

url = 'https://api.meraki.com/api/v0/networks/net1/httpServers '

headers = { 'Accept': 'application/json' }

response = requests.get(url=url, headers=headers, verify=False, timeout=5)

try:

response = requests.get(url, headers=headers, verify=False, timeout=5)

response.raise_for_status()

except requests.Timeout as e:

print("Timeout Error: {}".format(e))

if response.status_code == 200:

print(response.text)

This code makes a GET request to the specified URL, handles the timeout exception by printing a message, and prints the response body if the status code is 200.

References:

Requests: Handling Timeouts

Python Requests: Response Status Code

The Cisco Finesse platform is designed to provide a customizable interface for contact center agents and supervisors. One of its key characteristics is the ability to invoke services based on network-triggered events, allowing for dynamic and responsive workflows within the contact center environment.

XML (eXtensible Markup Language) uses tags to define the structure and content of the data. Each element is enclosed in tags, which makes the data self-descriptive and facilitates the hierarchical organization of information. This is a key feature that distinguishes XML from other data formats.

Cisco Intersight is a platform designed to manage data center infrastructure through third-party tools and system integrations. It provides a unified management platform that integrates with Cisco UCS, HyperFlex, and other data center components, allowing for comprehensive infrastructure management, automation, and orchestration.

References:

Cisco Intersight - Overview

Cisco DevNet Associate Certification Guide

When conflicts occur during a merge, the git merge --abort command can be used to stop the merge process and revert the repository to its state before the merge began.

Merge Conflicts: Occur when changes from different branches cannot be automatically reconciled.

Abort Merge: git merge --abort undoes the merge process and restores the pre-merge state of the repository.

Option D is correct as it correctly uses the git merge --abort command to revert to the pre-merge state.

The Dynamic Host Configuration Protocol (DHCP) is responsible for automatically assigning IP addresses to devices on a network. When a device connects to the network, it sends a broadcast request for an IP address, and a DHCP server responds with an IP address, subnet mask, default gateway, and DNS server information. This process simplifies network administration by automating IP address assignment and ensuring that devices have unique IP addresses without manual configuration.

References:

Cisco DHCP Overview

RFC 2131: DHCP

To minimize the security risk, storing the username and password in a vault is the best practice. A vault, such as HashiCorp Vault or AWS Secrets Manager, securely stores and manages sensitive information, providing encryption and access control. This approach ensures that credentials are not hard-coded or stored in insecure locations, reducing the risk of exposure.

To complete the requests and retrieve all the data, the correct code that needs to be added is next_url = response_json['metadata']['links']['next']. This ensures that the script retrieves the URL for the next set of data from the 'links' object within the 'metadata' section of the JSON response. This allows the loop to continue until all data is collected.

The Ansible playbook in the exhibit consists of two stages:

Stage 1: Restarts the network service on the eth0 interface.

Stage 2: Starts the httpd service.

Stage 1:

- name: stage1

ansible.builtin.service:

name: network

state: restarted

args: eth0

This stage ensures that the network service on the eth0 interface is restarted.

Stage 2:

- name: stage2

ansible.builtin.service:

name: httpd

state: started

This stage ensures that the httpd service is started if it is not already running.

References:

Ansible Playbook Documentation: Ansible Service Module

To clone the "myproject" repository from GitHub into a new folder named "aci" for optimization, the correct command is:

git clone git@github.com:myproject aci

This command specifies the SSH URL of the repository (git@github.com

) and sets the target directory to "aci." The git clone command copies the repository to the local machine, creating a new directory named "aci" where the repository's contents will be placed.

References:

Git Clone Documentation

GitHub SSH Setup

The YANG model provided in the exhibit defines the structure for interface information, including fields for name, admin-status, if-index, and statistics. The correct XML snippet must match this structure and use the appropriate namespaces and field names as defined in the YANG model.

Namespace: The XML must include the namespace urn:ietf:params:xml:ns:yang:ietf-interfaces and the prefix if.

Interface Information: The XML must include elements for name, admin-status, if-index, and statistics as defined in the YANG model.

Field Names and Values: The field names must match the YANG model (admin-status, if-index, in-octets, in-unicast-pkts).

Option D is the correct XML snippet because it accurately conforms to the YANG model. It includes the required elements and correctly uses the namespace and field names:

GigabitEthernet1

<admin-status>1</admin-status>

1

408164820

728061

RESTCONF is a protocol used to access data defined in YANG using standard HTTP methods. However, it does not support distributed transactions, which is a requirement in this scenario.

RESTCONF: Supports YANG data models, XML encoding, and can be used in environments with software redundancy.

Distributed Transactions: RESTCONF does not support distributed transactions, which require coordination of a transaction across multiple network devices or components.

Option C is correct as the requirement for distributed transactions prevents the use of RESTCONF.

The Cisco DevNet Sandbox provides a virtual environment where engineers and developers can access and run tests on various Cisco controllers and infrastructure components. This service offers always-on and reservation-based sandboxes that simulate real-world environments.

DevNet Sandbox: The Sandbox offers various environments with preconfigured Cisco devices and APIs, allowing engineers to run tests and develop solutions without affecting live systems.

Always-On Sandboxes: These environments are always available and can be used without reservation.

API Access: The Sandbox environments include access to APIs, enabling comprehensive testing and integration.

References:

Cisco DevNet Sandbox: DevNet Sandbox

Simplifying the wording: Webhook enables the app to ( push or receive real time) . The clients Webhooks enable applications to receive real-time data by providing a mechanism for one application to send data to another as soon as an event happens. This is done through HTTP callbacks, where an event in the source system triggers an HTTP POST request to a predefined URL in the destination system. This allows the destination system to process the data immediately, ensuring real-time updates.

The TCONNECT protocol is part of the OSI transport layer, where TCONNECT confirm is the API called when the remote transport user (TU) responds to a connection request from the local TU.

TCONNECT confirm: This is the final step in establishing a transport connection, where the remote TU confirms the connection request from the local TU.

Sequence: The sequence typically involves TCONNECT request, TCONNECT indication, TCONNECT response, and finally TCONNECT confirm.

References:

OSI Transport Protocols: OSI Transport Layer

NTP (Network Time Protocol) is the protocol used for clock synchronization between network devices. It synchronizes the clocks of computers and network devices to ensure that all devices in a network have the same time, which is crucial for logging events, security protocols, and coordinating time-sensitive operations.

The HTTP status code 201 indicates that a request has been fulfilled and has resulted in the creation of a new resource. In the context of the RESTCONF query provided in the exhibit, which includes a POST method to create or configure a resource, the expected successful response should be 201. This status code confirms that the new logging monitor resource has been created successfully on the Cisco IOS-XE device.

References:

Cisco DevNet Documentation - RESTCONF

MDN Web Docs - HTTP 201 Created

The AXL (Administrative XML) API is a SOAP-based API used by Cisco Unified Communications Manager (CUCM) to allow third-party applications to perform administrative tasks. One of the key capabilities of the AXL API is that it allows users to execute SQL commands within CUCM. This capability can be used to query and modify the CUCM database, enabling tasks such as retrieving information about users, devices, and configurations, or making updates to the CUCM system.

References:

Cisco DevNet Associate Certification Guide

Cisco Unified Communications Manager AXL Developer Guide

Python classes are a fundamental aspect of object-oriented programming (OOP) in Python. They offer several benefits:

Improved Code Organization: Classes bundle data (attributes) and functionality (methods) together. This encapsulation helps keep related parts of the code together, making it easier to understand and manage.

Reusability and Inheritance: Classes support inheritance, allowing the creation of new classes based on existing ones. This promotes code reuse and can lead to a more logical structure.

Modularity: By using classes, you can create modules that encapsulate specific functionalities, making the code modular and easier to maintain.

Encapsulation and Abstraction: Classes allow for encapsulating data and functionality, providing a clear structure and abstraction layers, which enhance code readability and maintainability.

References:

Python Classes and Objects - W3Schools

Python Documentation on Classes

An Ethernet switch operates at the Data Link layer (Layer 2) of the OSI model. Its primary function is to forward frames between devices based on their MAC (Media Access Control) addresses. When a frame arrives at the switch, the switch reads the destination MAC address and forwards the frame to the appropriate port that connects to the device with that MAC address.

MAC Address Table: Switches maintain a MAC address table that maps each MAC address to a specific port. This table is built dynamically as the switch learns the MAC addresses of devices connected to its ports.

Frame Switching: By using the MAC address table, the switch can efficiently switch frames only to the destination port, which reduces unnecessary traffic on other ports and improves network performance.

References:

Cisco DevNet Associate Certification Guide

Cisco Ethernet Switch Operation

The HTTP 401 Unauthorized error indicates that the request lacks proper authentication credentials. However, in this case, the credentials are provided, so the issue likely stems from a missing or incorrect header. The Content-Type header is necessary for many REST APIs to specify the format of the request body. Adding the Content-Type: application/yang-data+json header ensures that the server correctly interprets the request as JSON formatted data according to the YANG data model.

References:

Cisco DevNet Associate Certification Guide

Cisco IOS XE RESTCONF API Documentation

To address security concerns about sensitive information such as usernames and passwords in the application code, the best approach is to utilize environment variables. This is a common and recommended practice to enhance security because:

Environment Variables: Storing sensitive information in environment variables helps prevent exposure of these details in the codebase. They can be easily managed and changed without modifying the code.

Separation of Configuration from Code: This approach follows the principle of separating configuration from code, making the application more secure and easier to manage.

Security Best Practices: Using environment variables aligns with security best practices for managing secrets, which include not hard-coding sensitive data and keeping them outside the source code repository.

Hence, using environment variables for storing sensitive details like usernames and passwords (Answer B) is the appropriate and secure solution.

A firehose webhook in the context of Cisco Webex allows an application to receive real-time data updates about events happening within Cisco Webex. It enables the application to subscribe to a stream of data, ensuring that the application receives immediate notifications about any updates or changes in the Webex environment. This is particularly useful for integrating Webex functionalities into other applications and ensuring they are synchronized with the latest data.

References:

Cisco DevNet Associate Certification Guide

Cisco Webex API Documentation

Injection attacks occur when untrusted data is sent to an interpreter as part of a command or query. The attacker's hostile data can trick the interpreter into executing unintended commands or accessing data without proper authorization. Common types of injection attacks include SQL injection, command injection, and LDAP injection. These types of attacks exploit vulnerabilities in how an application processes input data, allowing attackers to inject malicious commands or queries into the system.

The YANG module shown in the exhibit is for interface management. It augments the ietf-interfaces module and defines parameters specific to Ethernet interfaces, such as auto-negotiation, duplex mode, and speed. This module is designed to manage the configuration and operational state of Ethernet interfaces. References for YANG modules can be found in the IETF YANG Data Model for Interface Management.

Layer 2 switches use MAC (Media Access Control) addresses to direct packet transmission to the intended recipient.

MAC Address: A unique identifier assigned to network interfaces for communication on the physical network segment.

Switching: Layer 2 switches maintain a MAC address table to keep track of which MAC addresses are associated with which ports, enabling them to forward frames to the correct destination port.

When consuming a RESTful API that returns large amounts of data, pagination is commonly used to divide the data into manageable chunks. Pagination helps reduce the load on the server and the client by providing only a subset of the total data in each response. The client can request the next set of data using parameters such as page or limit.

A firewall is a network device that monitors incoming and outgoing traffic and decides whether to allow or block specific traffic based on a defined set of rules.

Function of a Firewall:

Traffic Monitoring: It continuously monitors all traffic passing through it.

Rule-Based Filtering: It applies predefined security rules to allow or deny traffic.

Protection: It protects networks from unauthorized access and cyber threats.

Comparison with Other Devices:

Switch: A network device that connects devices within a LAN and uses MAC addresses to forward data to the correct destination.

Load Balancer: Distributes network or application traffic across multiple servers to ensure no single server becomes overwhelmed.

Reverse Proxy: A server that sits in front of web servers and forwards client requests to those web servers.

Therefore, a firewall is the correct answer because it specifically monitors and filters network traffic based on security rules.

References:

Cisco Firewalls Overview: Cisco Firewall Products

gRPC = C, NETCONF = A, RESTCONF = B, D

OR

The HTTP status code 400 indicates that the server cannot or will not process the request due to a client error.

HTTP Status Code 400 - Bad Request:

Meaning: The server cannot process the request due to a client-side error. This could be due to malformed request syntax, invalid request message framing, or deceptive request routing.

Common Causes: Typical reasons for a 400 Bad Request include incorrect URL formatting, invalid query parameters, or unsupported characters in the request.

Client Error Category: Status codes in the 4xx range indicate client errors, where the problem lies with the request sent by the client rather than the server.

Other Status Codes:

100 - Continue: Informational status code indicating that the initial part of a request has been received and the client can continue with the rest of the request.

203 - Non-Authoritative Information: The server successfully processed the request, but the information may come from a different source.

303 - See Other: The server is redirecting the client to a different resource, typically using the GET method.

References:

HTTP Status Codes: MDN Web Docs

RFC 7231: HTTP/1.1 Semantics and Content

1 – D, 2 – B, 3 – C, 4 – E, 5 – A

API keys should be stored securely to prevent unauthorized access. The best practice is to store them encrypted in a configuration file that is separate from the code. This approach ensures that sensitive information is not hardcoded in the source code, which could be exposed through version control or other means. Keeping API keys in encrypted configuration files also allows for better management and updating of keys without changing the application code.

1 - d, 2 - f, 3 - b, 4 - h, 5 - i, 6 – j, 7 - g, 8 - a, 9 - c, 10 - e

When configuring a Cisco IOS XE device using RESTCONF, the default data-encoding method is XML. RESTCONF is a protocol used to access configuration data and operational data using a REST-like API, and it uses XML as the default encoding method for data exchange.

XML: Used as the default encoding method for RESTCONF.

x-form-encoding: Not used by RESTCONF.

YANG: A data modeling language used to model configuration and state data manipulated by NETCONF and RESTCONF, but not an encoding method.

YAML: Not used by RESTCONF.

Solution below

To list the networks in a Meraki organization using the Meraki API, you need to construct a proper cURL command. The command must include the URL endpoint specific to the Meraki organization ID and the required API key for authentication. The correct cURL command to list networks in the organization with ID 384279060 is:

curl -X GET -L \

--url https://api.meraki.com/api/v0/organizations/384279060/networks \

-H 'X-Cisco-Meraki-API-Key: $meraki_api_key'

Here:

-X GET: Specifies the request method as GET.

-L: Follows any redirects.

--url: Specifies the API endpoint URL.

-H 'X-Cisco-Meraki-API-Key: $meraki_api_key': Adds the API key header for authentication.

References: Cisco DevNet Associate Certification Guide, Chapter on Cisco Meraki APIs and REST API calls.

git add .

git commit -m “this is my edit”

git push

1 – B, 2 – E, 3 - F

For Basic Authentication in REST APIs, the Base64 encoded credentials must be included in the header of the HTTP request. The correct method is to include the following header in the request:

Authorization: Basic am9objowMTlzNDU2Nzg=

References: Cisco DevNet Associate Certification Guide, Chapter on REST API Authentication methods.

When users cannot access a web server and the captured traffic shows an ICMP packet that reports "communication administratively prohibited," it indicates that there is a filtering device along the path, such as a router or firewall, that is intentionally blocking the traffic. This usually happens because of an access control list (ACL) that is set to deny the traffic to the webserver.

Access Control Lists (ACLs): ACLs are used in networking to control the flow of traffic into or out of a network. They can be configured on routers, firewalls, or other devices to allow or deny traffic based on IP addresses, protocols, ports, and other criteria.

ICMP Messages: ICMP (Internet Control Message Protocol) is used by network devices to send error messages and operational information. The "communication administratively prohibited" message specifically indicates that a device along the path has been configured to block the traffic.

Troubleshooting Steps:

Check ACL Configuration: Verify the ACL settings on all devices along the path to ensure that they are not blocking the required traffic.

Review Network Device Logs: Check logs on routers and firewalls for entries that match the blocked traffic.

Modify ACLs: If an ACL is found to be blocking the traffic, modify it to allow the required traffic to pass through.

References:

Cisco Documentation on ACLs: Access Control Lists

Cisco ICMP Overview: ICMP Messages

Cisco IOS XE supports model-driven programmability using protocols such as gNMI (gRPC Network Management Interface). gNMI is a protocol that provides a way to manage and configure network devices using a standardized approach to data models and APIs.

Model-Driven Telemetry: gNMI is used for streaming telemetry data from network devices.

Configuration Management: It allows for the configuration of network devices using standardized YANG models.

In the exhibit, the unified diff output shows changes made to the single_request_timeout method in a Python script. The modifications include:

Removing the assert statement that checks if the value is None or greater than 0.

Adding a raise ValueError statement to ensure that the single_request_timeout must be a positive integer if the value is not None.

These changes can be seen in the sections labeled with @@ -160,11 +160,12 @@ indicating the lines in the original and modified files. The lines starting with - indicate removed lines, and those starting with + indicate added lines. This type of change is typical in code updates to improve validation and error handling.

This Python script uses the Cisco DNA Center API to retrieve a list of network devices. The steps are:

Import the required libraries: requests for making HTTP requests and json for handling JSON data.

Define the API endpoint URL for retrieving network devices from Cisco DNA Center.

Set up the request headers, including the content type and the authentication token (X-Auth-Token).

Send a GET request to the API endpoint.

Check the response status code to ensure the request was successful.

If successful, parse and print the JSON response containing the list of network devices. Otherwise, print an error message.

When authenticating a RESTCONF API session with a router running Cisco IOS XE software, basic authentication is commonly used. Basic authentication involves sending the username and password in the HTTP header encoded in base64 format. This method is straightforward and widely supported, though it is less secure compared to token-based authentication and should be used with HTTPS to ensure the credentials are encrypted in transit.

When converting XML to JSON, the structure should maintain the hierarchical organization and data representation. The provided XML structure:

10.00

9.00

8.00

20.00

<algebra>12.00</algebra>

translates to the following JSON structure:

{

"books": {

"science": {

"biology": "10.00",

"geology": "9.00",

"chemistry": "8.00"

},

"math": {

"calculus": "20.00",

"algebra": "12.00"

}

}

}

Root Element: The root element translates to a key "books".

Nested Elements: The and $elements\; become\; nested\; objects\; under\; "books".$

Leaf Elements: The individual subjects and their prices (e.g., 10.00) become key-value pairs within their respective parent objects.

Option A:

json

Copy code

{

"books": {

"science": {

"biology": "10.00",

"geology": "9.00",

"chemistry": "8.00"

},

"math": {

"calculus": "20.00",

"algebra": "12.00"

}

}

}

This option accurately represents the hierarchical structure of the XML data, making it the correct equivalent.

Option B, C, and D:

These options incorrectly use array notation for the nested objects, which is not consistent with the original XML structure. The XML structure indicates that "science" and "math" are single objects with multiple key-value pairs, not arrays.

References:

Converting Between XML and JSON

JSON and XML Comparison

VLANs (Virtual Local Area Networks) serve several purposes in a network. Two primary purposes are:

Segmentation of the Network: VLANs logically segment a network into different broadcast domains, which helps in managing and controlling broadcast traffic. This segmentation helps improve performance and security by isolating certain types of traffic from others.

Creating Broadcast Domains: Each VLAN is a separate broadcast domain. By using VLANs, a network administrator can reduce the size of broadcast domains, thereby reducing broadcast traffic and increasing the efficiency of the network.

These purposes are in line with Cisco's network design principles and best practices for using VLANs. References: Cisco DevNet Associate Certification Guide, Chapter on VLANs and their uses.

Edge computing solutions are utilized where low latency is needed. Edge computing involves processing data closer to where it is generated (at the edge of the network), which reduces the latency compared to sending data to a centralized data center for processing.

Low Latency Needs: Edge computing is designed to provide real-time data processing and decision-making by reducing the distance data has to travel. This is crucial for applications requiring immediate data processing, such as IoT devices, autonomous vehicles, and real-time analytics.

References: Cisco DevNet Associate Certification Guide, Chapter on IoT and Edge Computing.

1 - d, 2 - i, 3 - e, 4 - a, 5 - j, 6 - b, 7 - g, 8 - h, 9 - c, 10 - f

A default gateway serves as an access point or IP router that a networked computer uses to send information to a computer in another network or the internet. It is essentially the forwarding node that routes traffic from a local network to other networks. When an IP packet's destination is not within the local network and no specific route is defined in the routing table, the packet is sent to the default gateway.

DNS (Domain Name System) is the service that provides a directory lookup for IP addresses and host names. DNS translates human-readable domain names (like www.example.com ) into IP addresses that computers use to identify each other on the network.

DNS: Converts domain names into IP addresses and vice versa.

DHCP: Dynamically assigns IP addresses to devices on a network.

SNMP: Used for network management and monitoring.

NAT: Translates private IP addresses to a public IP address for accessing the internet.

References:

Cisco DNS Documentation

A routing table contains critical information used by routers to determine the best path for forwarding packets. The essential details included in a routing table are:

Destination network: The IP address of the destination network.

Next hop: The IP address of the next hop router or the outgoing interface to reach the destination network.

Metric: The cost associated with the path to the destination network, used to select the best route.

Route type: The type of route (e.g., directly connected, static, dynamic).

The Cisco DevNet Sandbox is a resource provided by Cisco that allows developers to access a variety of Cisco products in a development lab environment. This resource enables users to explore, learn, and build applications using Cisco APIs. The sandbox environment is equipped with pre-configured topologies and a range of Cisco technologies, offering a safe and secure space to experiment without the need for physical hardware.

DevNet Sandbox: Provides access to virtual environments for learning and development.

DevNet Communities: Are for discussions and collaboration among developers.

DevNet Code Exchange: Offers code repositories and examples for various Cisco technologies.

DevNet Automation Exchange: Focuses on automation scripts and tools shared by the community.

1 – A, 2 – B, 3 – D, 4 – C

 Asynchronous API calls are non-blocking, meaning the application can continue processing other tasks while waiting for the API call to complete. This helps improve the efficiency and responsiveness of the application. Typically, a callback function is used to handle the response once the API call completes.

Option B is correct because asynchronous API calls do not block the code; they allow the application to perform other operations concurrently.

Option E is correct because a callback function is usually implemented to handle the response of an asynchronous API call once it completes.

References:

Cisco DevNet Associate Exam Topics: APIs and Automation (understanding synchronous and asynchronous API calls)

Asynchronous Programming Documentation (explains how asynchronous calls work and the use of callbacks)

The exhibit demonstrates an example of cross-site scripting (XSS). This type of attack involves injecting malicious scripts into web pages viewed by other users. In this example, the script <script>alert('I want to pass the DevNet Associate Exam.');</script> is embedded into a URL, and when accessed, it displays an alert message in the web browser.

Cross-Site Scripting (XSS): A security vulnerability typically found in web applications that allows attackers to inject malicious scripts into content from otherwise trusted websites.

References: Cisco DevNet Associate Certification Guide, Chapter on Security, and OWASP documentation on Cross-Site Scripting.

By segmenting the network into separate subnets for clients and servers, you can control the types of traffic that flow between these segments using access control lists (ACLs) and firewall rules. This can enhance security by limiting access to critical server resources and reducing the risk of unauthorized access.

Subnets will split domains to limit failures (Option C):

Segmenting the network into different subnets helps contain network issues within a specific segment, preventing them from affecting the entire network. This approach improves network stability and reliability, as issues in the client subnet will not impact the server subnet and vice versa.

References:

Cisco Subnetting and Network Segmentation

Cisco Router and ACL Configuration Guide

Top of Form

Bottom of Form

Routing protocol traffic is handled on the control plane of a network device. The control plane is responsible for the exchange of routing information, the computation of the best paths, and the creation of the routing table. Protocols such as OSPF, BGP, and EIGRP operate at the control plane level to ensure that routers have the necessary information to make forwarding decisions. The data plane, on the other hand, is responsible for the actual forwarding of packets based on the routing table created by the control plane. More information on network planes can be found in the Cisco Networking Basics.

The two protocols used to apply configuration changes on a Cisco IOS XE device are:

RESTCONF: A REST-like protocol used for accessing data defined in YANG, using the datastore concepts defined in NETCONF. It allows the application of configurations and retrieval of state information using HTTP methods.

NETCONF: A protocol defined to manage configurations and monitor devices. It uses remote procedure calls (RPCs) to apply changes in a structured data format defined by YANG.

References: Cisco DevNet Associate Certification Guide, Chapter on Network Management Protocols including NETCONF and RESTCONF.

The Model-View-Controller (MVC) design pattern is a software architectural pattern that separates an application into three main logical components: the Model, the View, and the Controller. Each of these components is built to handle specific development aspects of an application.

Advantages of MVC:

Allows for multiple views of the same model (Option B):

In the MVC architecture, the Model component represents the data and the business logic of the application. It is independent of the user interface. This separation allows the application to have multiple views that can present data in different ways without requiring changes to the underlying data model. For example, the same data can be displayed in a web application, a mobile app, or even a command-line interface, all using the same model.

Separates responsibilities of the code, which makes future modifications easier (Option E):

By separating the application into distinct components (Model, View, Controller), MVC clearly defines the responsibilities of each part. The Model is responsible for data management, the View for the user interface, and the Controller for handling user input and interactions. This separation of concerns makes the application easier to maintain and modify. Future changes can be made to one component without significantly affecting the others. For instance, changes to the user interface can be made in the View without altering the underlying data model or the business logic in the Model.

Other Considerations:

Simplifies network automation (Option A): While MVC can be used to create applications that interact with network automation tools, simplifying network automation is not a direct advantage of the MVC pattern itself.

Makes code easier to deploy using CI/CD pipelines (Option C): CI/CD pipelines benefit from modular and well-structured code, but the MVC pattern specifically addresses the organization of code and separation of concerns, rather than deployment processes.

Reduces need for error handling (Option D): Error handling is an essential aspect of any application and is not inherently reduced by the use of MVC. Instead, MVC helps in organizing the code in a way that might make error handling more systematic, but it does not directly reduce the need for it.

The separation of concerns and the ability to have multiple views of the same model are core advantages of using the MVC pattern, making it a powerful design approach for creating scalable and maintainable applications.

References:

Model-View-Controller (MVC) Architecture

Cisco DevNet Developer Resources

A version control system offers several advantages:

Branching and Merging: Developers can work on features, bug fixes, or experiments in isolation (branches) without affecting the main codebase. Once the work is completed, it can be merged back into the main branch, facilitating organized and controlled development workflows.

Test-driven development (TDD) is a software development process where the developer first writes a test for a new function, then writes the code to pass the test, and finally refactors the code. The steps in TDD are:

Write a Failing Test Case: Before any code is written, a test case is created to define the desired functionality.

Write Code to Pass the Test: The minimal amount of code necessary to pass the test is written.

Refactor: The code is refactored for optimization and improvement while ensuring that the tests still pass.

When a developer is writing an application that interacts with a REST API, the status code of the response is a critical element used in conditional checks. The status code provides information about the success or failure of the request. Common status codes include:

200: OK (The request was successful).

201: Created (The resource was successfully created).

400: Bad Request (The server could not understand the request due to invalid syntax).

401: Unauthorized (Authentication is required and has failed or has not been provided).

404: Not Found (The requested resource could not be found).

By checking the status code, the application can determine if the request was successful and handle errors appropriately.