Cisco 200-901 Dumps

The developer can use the Cisco DevNet API documentation to get detailed information on how to use the API for automated data collection from Webex. The API documentation includes comprehensive guides, usage examples, and authentication methods such as HTTP basic authentication. This resource helps developers understand the data formats (JSON or XML) and provides code snippets and best practices for implementation. Cisco DevNet API documentation is designed to assist developers in integrating their applications with Cisco's APIs effectively.

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 MAC (Media Access Control) address is a unique identifier assigned to network interfaces for communications at the data link layer of a network segment. Key features of a MAC address include:

Length and Format: A MAC address is 48 bits in length, typically represented as 12 hexadecimal digits (e.g., 00:1A:2B:3C:4D:5E).

Hexadecimal Representation: The 12 hexadecimal digits are often grouped into pairs separated by colons or hyphens for readability (e.g., 00:1A:2B:3C:4D:5E or 00-1A-2B-3C-4D-5E).

References:

IEEE 802 MAC Address Standard

Cisco MAC Address Basics

Rate limiting, as explained previously, is essential to ensure that an application can handle traffic spikes without crashing. By limiting the rate at which requests are processed, the application can maintain stability and reliability under varying load conditions.

Traffic Spike Management: Rate limiting helps manage unexpected surges in traffic by capping the number of allowable requests within a specified period.

Reliability Maintenance: By preventing overloading, rate limiting ensures that the application remains operational and responsive, maintaining its reliability.

References:

Managing Traffic Spikes with Rate Limiting: Rate Limiting Strategies

When configuring a Cisco IOS XE networking device using RESTCONF, the default data encoding method is application/yang-data+json. This MIME type indicates that the data is encoded in JSON format and structured according to YANG data models. YANG (Yet Another Next Generation) is a data modeling language used to model configuration and state data manipulated by the NETCONF protocol, which RESTCONF leverages.

References:

Cisco DevNet Documentation - RESTCONF

Cisco DevNet Associate Certification Guide

In Ansible, when using the netconf_config module to automate configuration tasks that include unique interface variables for each device, the variables should be defined in individual YAML files within the host_vars directory. This directory contains host-specific variable files named after each host, allowing Ansible to load the appropriate variables for each device during playbook execution.

References:

Ansible Documentation - Variable precedence

Cisco DevNet Associate Certification Guide

Comparing a current version of code to a previous version is a common practice in software development for troubleshooting code failures. This process, often referred to as "diffing," helps developers identify changes that might have introduced bugs or caused the application to behave incorrectly. By pinpointing these changes, developers can more efficiently debug and resolve issues.

References:

Atlassian - Comparing code differences

Cisco DevNet Associate Certification Guide

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

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

The provided JSON configuration includes information about a GigabitEthernet interface with the name "2". To retrieve information about this specific interface using a RESTCONF API call, the correct HTTP method and URL must be used.

HTTP Method: The GET method is used to retrieve information from the server.

Correct URL: The URL must specify the path to the particular interface. The correct URL structure includes the native and interface resources, followed by the interface type (GigabitEthernet) and its specific name ("2").

The correct RESTCONF API call to retrieve the information would be:

GET

This URL correctly targets the specific GigabitEthernet interface named "2" in the running configuration.

References:

Cisco RESTCONF API Documentation: RESTCONF API Guide

Model-driven programmability refers to the use of a consistent data model to manage and automate network devices. Key capabilities include:

Single Data Model Across the Network: Ensures uniformity and consistency in how data is represented and managed across different network devices and platforms.

Automation and Scalability: Facilitates automated network configurations and operations, enabling scalability.

Interoperability: Using standardized models (like YANG) allows for interoperability between different network devices and management tools.

Abstracted API Interfaces: Provides abstracted and consistent APIs that can be used across multiple devices, reducing the complexity of network automation scripts.

References:

Cisco Model-Driven Programmability

Virtual machines (VMs) provide the flexibility and capabilities required to meet the described requirements. VMs can easily migrate between data centers, save and restore their state, and support various operating systems and GUIs.

Migration: VMs can be moved from one physical server or data center to another, providing high flexibility in resource management.

State Saving: VMs support saving the operational state (snapshots), allowing quick recovery or migration.

Support for GUIs: VMs can run different operating systems, including those with graphical user interfaces (GUIs) like Windows and Linux.

Hardware Utilization: VMs enable better utilization of hardware resources by running multiple VMs on a single physical host.

References:

Virtual Machines Overview: VMware VMs

The exhibit shows that the credentials are base64 encoded and included in the source code. Base64 encoding is not a secure method of protecting credentials as it can be easily decoded. Therefore, an attacker who gains access to the source code can decode the credentials and gain unauthorized access to the account. Proper security practices should involve storing credentials securely, such as using environment variables or secure vaults, and not hardcoding them in the source code.

References:

OWASP - Storing Passwords Securely

Cisco DevNet Associate Certification Guide

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.

In a CI/CD (Continuous Integration/Continuous Deployment) pipeline, it is a common procedural component that every test must pass for the pipeline to continue its execution. This ensures that only code that meets the quality standards and passes all tests is deployed, thereby reducing the risk of introducing bugs or issues into the production environment.

Infrastructure as Code (IaC) applies software development practices to infrastructure management. This approach uses code to provision and manage IT infrastructure, enabling version control, automated testing, and continuous delivery.

Automated Provisioning: IaC scripts automate the setup and configuration of infrastructure resources.

Consistency: By defining infrastructure in code, environments can be consistently reproduced across different stages (development, testing, production).

Development Practices: IaC allows infrastructure to be managed with the same tools and processes as application code, including version control and automated testing.

References:

Infrastructure as Code Overview: IaC Introduction

from ucsmsdk.ucshandle import UcsHandle

connection = UcsHandle("10.10.20.113", "ucspe", "ucspe")

connection.login()

orgs = []

ucsm_orgs = connection.query_classid("orgOrg")

for org in ucsm_orgs:

temp_org = {"name": org.name, "dn": org.dn, "rn": org.rn}

orgs.append(temp_org)

print(orgs)

Understanding the UCSHandle Class:

Purpose: The UcsHandle class is used to interface with the UCS Manager.

Parameters: It requires parameters like IP address, username, password, port, secure, and proxy.

Python Script Explanation:

Importing UcsHandle: The first step is to import the UcsHandle class from the ucsmsdk.ucshandle module.

Creating a Connection: An instance of UcsHandle is created with the UCS Manager's IP address, username, and password.

Login: The login() method is called on the UcsHandle instance to establish a session with the UCS Manager.

Querying Organizations: The query_classid() method is used to retrieve objects of a specific class, in this case, "orgOrg" which represents organizations.

Looping through Results: The script iterates over the retrieved organizations, extracting their name, distinguished name (dn), and relative name (rn), and appending this information to the orgs list.

Printing Results: Finally, the orgs list is printed, which contains the details of all the organizations.

References:

Cisco DevNet Associate Certification Guide, Sections on UCS Manager API and Python SDK

UCS Python SDK Documentation

Nonlinear development in a version control system like Git allows developers to work on different parts of the project independently and simultaneously. This approach provides several advantages:

Independent Workflows: Developers can work on different features or bug fixes without interfering with each other's work.

Parallel Development: Multiple branches enable parallel development, where teams can develop, test, and merge features separately.

Efficient Collaboration: Changes can be reviewed, tested, and merged systematically, improving collaboration among remote teams.

References:

Git and Nonlinear Development: Understanding Git Workflow

A hybrid cloud deployment model combines elements of both private and public clouds, providing the scalability needed for fast deployment of new nodes for data and indexing. It allows for sensitive information to be stored in a private cloud where specialist encryption tools can be used, while non-sensitive data can be stored in the public cloud to take advantage of its scalability and cost benefits. This approach meets the requirements of both scalability and data security.

RPC (Remote Procedure Call) APIs and REST (Representational State Transfer) APIs have different approaches to communication and authentication.

RPC APIs: Authentication can be more complex and is often embedded within the service calls themselves, sometimes requiring specific provisions for the caller and the service.

REST APIs: Authentication typically relies on standardized methods such as HTTP headers, including Basic Auth, OAuth tokens, or API keys, making it more straightforward and standardized across different services.

References:

Cisco DevNet Documentation - APIs

Cisco DevNet Associate Certification Guide

Refer to the exhibit which shows a sequence diagram illustrating a client-server interaction. The correct sequence of steps that match the code snippet is as follows:

Step 1: POST /events - The client posts an event to the server.

Step 2: GET /messages/<messageId> - The client retrieves the message details from the server using the message ID.

Step 3: Response /messages/<messageId> - The server responds with the message details.

Step 4: GET /team-memberships?teamId=<teamId> - The client retrieves team membership details using the team ID.

Step 5: POST /message - The client posts a message.

Step 6: Response /message - The server responds with the message confirmation.

The correct code snippet represents the sequence diagram correctly:

@flask_app.route('/events', methods=['POST'])

def webex_teams_webhook_events():

json_data = request.json['data']

response = requests.get(MESSAGE_URL + json_data['id'], headers=headers)

if response.json()['text'] == 'Alert':

response = requests.get(TEAM_MEMBERSHIPS_URL, headers=headers, params=params)

for info in response.json()['items']:

data = {'personId': info['personId'], 'text': 'Alert'}

Distributed version control systems (DVCS) like Git provide a local repository for each user, allowing them to work on the codebase offline. Changes can be committed locally and later synchronized with the central repository once connected to the Internet.

Local Repositories: Each user has a complete copy of the repository, enabling offline work.

Synchronization: Changes can be committed and later pushed to the central repository.

Option C is correct as it highlights the benefit of working on the codebase without an Internet connection.

NETCONF (Network Configuration Protocol) operates over TCP port 830. It is a protocol defined for managing network devices and configurations. NETCONF provides mechanisms to install, manipulate, and delete the configuration of network devices. It uses XML as its data encoding format and allows for easy automation of network configuration tasks.

References:

Cisco DevNet Associate Certification Guide

RFC 6241 - Network Configuration Protocol (NETCONF)

The data plane, also known as the forwarding plane, is responsible for handling the actual movement of packets through the network device, including Quality of Service (QoS). QoS involves managing and prioritizing network traffic to ensure that critical applications receive the necessary bandwidth and performance levels. The data plane processes and forwards data packets based on the policies set by the control plane.

References:

Cisco DevNet Associate Certification Guide

Cisco Networking Essentials, Chapter on Network Device Planes

A default gateway is a router or network device that serves as an access point to another network, often the internet, when no other route is specified for a given data packet. In other words, it is used to forward traffic from the local subnet to different subnets, including external networks. When a host needs to communicate with a device on a different subnet, it sends the traffic to the default gateway, which then routes the traffic accordingly.

References:

Cisco DevNet Associate Certification Guide

Cisco Networking Essentials, Chapter on Routing and Switching Basics

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.

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

import requests

data = {

"id": 11,

"summary": "Request summary"

}

response = requests.post(' ', json=data)

if response.status_code != 201:

raise ApiError('POST /tasks/ {}'.format(response.status_code))

for item in response.json():

print('{} {}'.format(item['id'], item['summary']))

Importing the Requests Library:

The requests library is used to make HTTP requests in Python. It is a popular third-party library that simplifies interactions with web APIs.

Creating the Data Payload:

The data dictionary contains the information to be sent in the body of the POST request. It includes an id and a summary.

Making the POST Request:

The requests.post method is used to send a POST request to the specified URL The json=data parameter automatically converts the data dictionary to a JSON-formatted string and sets the appropriate headers.

Checking the Response Status Code:

The script checks if the status_code of the response is not equal to 201. A status code of 201 indicates that the request was successful and a resource was created.

If the status code is not 201, an ApiError is raised with a message that includes the status code.

Processing the JSON Response:

The response.json() method is used to parse the JSON response into a Python dictionary.

The script iterates over the items in the JSON response and prints the id and summary of each item.

References:

Cisco DevNet Associate Certification Guide, Sections on interacting with REST APIs using Python

Official documentation for the Requests library: Requests: HTTP for Humans

The Administrative XML Layer (AXL) API in Cisco Unified Communications Manager (CUCM) allows for various administrative tasks, including the ability to authenticate users. It enables applications to interact with CUCM, retrieving user information, and authenticating users based on their credentials stored in CUCM.

Ansible playbooks are used to define the desired state of a device configuration. Playbooks contain a series of tasks that describe the configuration management, deployment, and orchestration tasks. They are written in YAML and are designed to be simple yet powerful, allowing users to define the state and ensure that devices are configured accordingly.

Rate limiting is a technique used to control the amount of incoming and outgoing traffic to or from a network. It restricts the number of API requests a user can make within a specified time window, protecting the application from being overwhelmed by too many requests at once.

Definition and Purpose: Rate limiting sets a threshold for the number of requests a user or system can make in a given timeframe (e.g., 100 requests per minute).

Implementation: Developers can implement rate limiting using various strategies such as token buckets or fixed windows.

Benefits: This constraint helps prevent abuse, reduces server load, and ensures the application remains available and performant even during high traffic periods or attacks.

References:

Rate Limiting and Throttling in APIs: Rate Limiting

The main security issue in this scenario is the transmission of credentials in cleartext over HTTPS. Even though HTTPS provides a secure transport layer, the credentials should still be protected, such as by using secrets or encryption. Additionally, setting logging to debug and potentially exposing these credentials in logs is also a security concern.

Cleartext Credentials: Sending credentials in cleartext within the webhook payload can expose them if HTTPS is not configured correctly or if intercepted by an attacker.

Debug Logging: Enabling debug logging can expose sensitive information, including credentials, in logs.

Option B highlights the risk of transmitting credentials unencrypted over HTTPS, which can lead to credential leakage.

Infrastructure as Code (IaC) principles relate to the service provisioning stage of development. IaC involves managing and provisioning computing infrastructure through machine-readable definition files, rather than through physical hardware configuration or interactive configuration tools.

Service Provisioning: IaC allows for the automated deployment and management of infrastructure resources. This includes servers, databases, networks, and other components necessary for running applications and services.

Automation and Consistency: IaC ensures that the infrastructure is provisioned consistently and repeatably, reducing the chances of human error and increasing efficiency.

References:

Cisco DevNet Associate Certification Guide

Infrastructure as Code (IaC) Principles

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 exhibit shows an XML configuration using NETCONF (Network Configuration Protocol) to edit the configuration of a network device. Specifically, the operation is being used with the nc:operation="delete" attribute within the element. This means that the configuration is intended to delete specific configurations related to the interface named FastEthernet0/0/3.9.

Here is the detailed explanation:

The element initiates a remote procedure call.

The element specifies the operation to be performed.

The element with indicates that the changes are to be made to the running configuration.

The element contains the configuration data to be applied.

Within , the element with nc:operation="delete" specifies that the interface configuration for FastEthernet0/0/3.9 is to be deleted.

This configuration does not affect all device configurations or shut down the device but deletes the specified interface configuration.

References:

Cisco DevNet Associate Certification Guide

RFC 6241 - Network Configuration Protocol (NETCONF)

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 copy a file from one directory to another and rename it in the process, the cp (copy) command in Linux can be used with the appropriate source and destination paths:

Command Breakdown:

cp: The copy command.

./TEST/config.txt: The source file path.

./PROD/current.txt: The destination file path with the new name.

Thus, the correct command to achieve this task is: cp ./TEST/config.txt ./PROD/current.txt

References:

Linux cp Command Manual

Cisco DevNet Associate Certification Guide

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).

RESTCONF is a protocol used for accessing data defined in YANG, using RESTful principles. It is suitable for retrieving configuration data in JSON format from a Cisco CSR 1000 V instance. RESTCONF allows network devices to be managed using HTTP methods, and it supports both XML and JSON as data formats, making it ideal for outputting device configurations in JSON.

Rate limiting is a technique to control the rate of incoming and outgoing traffic to or from a network. If rate limiting is not implemented, excessive API requests can overwhelm the server, causing long response times and abandoned requests.

Abandoned Requests: When a server is overwhelmed with too many requests, it may not process them all, leading to abandoned requests.

Long Response Times: Without rate limiting, the server might be handling more requests than it can efficiently process, resulting in delayed responses.

Solution: Implementing rate limiting ensures that the server processes requests at a manageable rate, improving performance and reliability.

References:

Rate Limiting and API Performance: Understanding Rate Limiting

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 = ' '

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 HTTP status code 200 indicates successful execution of a request.

Status Code 200:

Meaning: OK - The request has succeeded. The meaning of the success depends on the HTTP method:

GET: The resource has been fetched and is transmitted in the message body.

HEAD: The headers are in the message body.

POST: The resource describing the result of the action is transmitted in the message body.

TRACE: The message body contains the request message as received by the server.

Comparison with Other Codes:

404 - Not Found: The server can’t find the requested resource.

405 - Method Not Allowed: The request method is known by the server but is not supported by the target resource.

500 - Internal Server Error: The server encountered an unexpected condition that prevented it from fulfilling the request.

Thus, the status code 200 indicates that the request was successful.

References:

HTTP Status Codes: MDN Web Docs

There are two primary types of NAT (Network Address Translation) used in networking:

Static NAT: Maps a single private IP address to a single public IP address. This type of NAT is useful when you want a specific internal device (like a server) to be accessible from the internet using a consistent public IP address.

Dynamic NAT: Maps a private IP address to a public IP address from a pool of available public IP addresses. This type of NAT is used when you want internal devices to access the internet but do not require a consistent public IP address for each internal device.

Other types mentioned (Normal NAT, Multicast NAT, Router NAT) are not standard terms or widely recognized types of NAT.

The error message JSON-PARSE-ERROR and Unexpected character ('"' (code 34)) indicates a JSON formatting issue. Specifically, there is likely an incorrect character or misplaced quote within the JSON structure. Properly formatting the JSON payload and ensuring all fields are correctly quoted and syntax rules are followed will resolve this error.

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.

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.

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.

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.

A router is a network device that routes traffic between different broadcast domains and subnets. Routers operate at the network layer (Layer 3) of the OSI model and use IP addresses to make forwarding decisions. They are responsible for determining the best path for data packets to travel across interconnected networks, ensuring that traffic is correctly directed from one broadcast domain to another.

References:

Cisco Router Basics

Broadcast Domains and Routers

=========================

Test-Driven Development (TDD) is a software development approach where tests are written before writing the actual code. The steps involved in TDD are:

Write a test for the new functionality.

Run the test and see it fail (because the functionality is not yet implemented).

Write the minimum code necessary to make the test pass.

Refactor the code while keeping the test passing.

Option B is the correct answer because refactoring code while it is covered by existing tests is a key aspect of TDD. The existing tests ensure that the functionality remains correct even after refactoring.

References:

Cisco DevNet Associate Exam Topics: Software Development and Design (understanding TDD methodology)

"Test-Driven Development by Example" by Kent Beck (standard reference on TDD)

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.

Test-Driven Development (TDD) is a software development approach where tests are written before the code that needs to be tested.

TDD Process:

Write a Test: Start by writing a test for a new feature or functionality.

Run the Test: Run the test, which should fail initially since the code hasn’t been written yet.

Write Code: Write the minimum amount of code required to pass the test.

Run Tests Again: Run the tests again to ensure they pass.

Refactor: Refactor the code while ensuring the tests still pass.

Advantages:

Early Bug Detection: Bugs are detected early in the development cycle.

Better Design: Promotes writing cleaner, more modular code.

Documentation: The tests themselves serve as documentation for the code.

Writing and running tests before writing the actual code ensures that the code meets the specified requirements and functions correctly.

References:

TDD Overview: Test-Driven Development

Clients make several types of queries to DNS servers. The two relevant types here are:

AAAA: This query type requests the IPv6 address associated with a domain name.

PTR: This query type is used for reverse DNS lookups, where it maps an IP address to a domain name.

AAAA (Quad-A) records store IPv6 addresses of a domain.

PTR (Pointer) records are used in reverse DNS lookups to map IP addresses to the corresponding domain names.

References: DNS and BIND by Cricket Liu and Paul Albitz, Cisco DevNet Associate Certification Guide.

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.

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

Firewalls are used to control incoming and outgoing network traffic based on predetermined security rules, primarily by limiting traffic to only the necessary ports for an application.

Port Filtering: Firewalls can block or allow traffic based on port numbers, thus limiting exposure to only those ports required by the application, enhancing security.

Security: This helps to protect the application from unauthorized access and potential attacks by reducing the attack surface.

The Bash script shown performs the following actions:

It reads a directory name into the variable ndir.

It enters a loop that continues as long as the directory specified by ndir exists (-d "$ndir" checks if a directory exists).

Inside the loop, it changes the current directory to ndir.

Once the loop exits (when a directory with the name ndir no longer exists), it creates a new directory with the name stored in ndir.

Thus, the script ensures that it continues to navigate into directories with the given name until it finds one that does not exist, and then creates it.

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.

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

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.

Synchronous API Operations:

Immediate Response: In a synchronous operation, the client sends a request to the server and waits for an immediate response. The client cannot proceed until it receives this response.

Blocking Call: The call is considered blocking, meaning the client application is blocked from performing other tasks until the response is received.

Use Case: This is useful when the result of the operation is required immediately to continue the workflow.

Asynchronous API Operations:

Delayed Response: In an asynchronous operation, the client sends a request to the server and does not wait for an immediate response. Instead, it continues its processing and can check back later for the result.

Non-blocking Call: The call is non-blocking, allowing the client to perform other tasks while waiting for the server to complete the operation.

Polling and Webhooks: Clients may poll the server for status updates or subscribe to a webhook to be notified when the operation is complete.

Task ID: The server may provide a task ID in the response that can be used to check the status of the operation later.

References:

Cisco DevNet API Documentation: API Design Guide

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.

An artifact repository is a key component in a CI/CD pipeline, used to manage binary files and other artifacts produced and consumed during the build process. It helps in organizing and tracking these artifacts through various stages of the pipeline.

Provides Traceability, Search, and Management of Binary Files:

Artifact repositories store binary files and metadata, allowing developers to trace back to the source and understand the context in which an artifact was produced.

These repositories often come with search functionalities to locate specific versions of binaries quickly.

Examples include JFrog Artifactory, Nexus Repository, and AWS CodeArtifact.

Stores Files Needed and Generated During the Build Process:

Artifact repositories store intermediate and final build outputs, dependencies, libraries, and other necessary files.

These repositories support the storage and distribution of build artifacts, ensuring consistent deployment in different environments (e.g., staging, production).

YANG (Yet Another Next Generation) is a data modeling language used to model configuration and state data manipulated by the NETCONF protocol. Here are two advantages of YANG-based approaches for infrastructure automation:

Multi-platform vendor abstraction (Option B):

YANG provides a standardized way to model configuration and state data, enabling multi-platform vendor abstraction. This means that network engineers can write configurations and management scripts that work across different network devices from different vendors, as long as they adhere to the YANG model. This reduces the complexity and increases the interoperability in multi-vendor environments.

Designed to reflect networking concepts (Option C):

YANG is specifically designed to reflect networking concepts and constructs, making it intuitive and effective for defining network configurations and states. The hierarchical structure of YANG models aligns well with the structure of network configurations, allowing for precise and clear definitions of network elements and their relationships.

References:

Cisco YANG Overview

IETF YANG

To ensure the result set is returned in reverse chronological order based on when messages were entered, we need to use the sortBy parameter with the value lastactivity. This parameter sorts the rooms by their last activity timestamp, ensuring the most recent rooms are listed first.

Example:

GET /v1/rooms?sortBy=lastactivity

References:

Cisco Webex Teams API Documentation (explains query parameters and their usage in API calls)

Cisco DevNet Associate Exam Topics: APIs and Automation (understanding how to utilize query parameters to retrieve data)

In NETCONF, the operation retrieves all or part of a configuration and state data from the running datastore. The operation retrieves configuration data from a specific configuration datastore (e.g., running, startup). These operations correspond to the RESTCONF GET operation, which is used to retrieve configuration and state data from a network device. This mapping between NETCONF and RESTCONF operations is described in detail in the RFC 6241 for NETCONF and RFC 8040 for RESTCONF.

The described behavior, where an automation script fails to connect to an internal server exactly 50% of the time from different clients, suggests an issue with a load balancer. Load balancers distribute incoming network traffic across multiple servers to ensure reliability and performance. If a load balancer is misconfigured or if one of the backend servers is down, the connection might fail intermittently, which aligns with the described 1 out of 2 failure rate.

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.

1 – A, 2 – C, 3 – B

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 ) 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 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

The error message "JSON-PARSE-ERROR" and "Unexpected character ('"' (code 34))" indicates a problem with the formatting of the JSON payload. Specifically, there are likely incorrect characters or misplaced quotes within the JSON structure. JSON formatting issues are common errors that can occur due to syntax mistakes such as missing commas, incorrect braces, or invalid characters.

To resolve this, carefully check the JSON structure for proper formatting, ensuring all fields are correctly defined and that syntax rules are followed.

Solution as below

When using Basic Authentication in HTTP, the username and password are concatenated with a colon (:) in between. This concatenated string is then encoded using Base64. For the provided username devnet and password Cisco123, the string devnet:Cisco123 is encoded in Base64, resulting in ZGV2bmV0OkNpc2NvMTIz. This Base64 string is then included in the HTTP Authorization header. This process is described in the RFC 7617 and is a standard practice in HTTP Basic Authentication.

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.

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.

The script provided in the exhibit shows the following steps:

It configures a loopback interface (interface loopback 5; no shut).

It retrieves the interface details and parses the JSON output to list interfaces that are up.

Therefore, the correct answers are: A. Configure interface loopback 5. C. Show only the interfaces in the up status.

1 – E, 2 – B, 3 – D, 4 – A

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 Intersight API interactions can be encoded in XML or JSON and require an API key in the HTTP header for authentication: This statement is true. Cisco Intersight APIs support both XML and JSON formats for API interactions. API keys are used in the HTTP header to authenticate requests.

UCS manager API interactions are XML-encoded and require a cookie in the method for authentication: This statement is true. Cisco UCS Manager APIs typically use XML for encoding interactions, and a session cookie is required for authentication after an initial login request.

Cisco Intersight API: Uses either XML or JSON formats and requires API keys for authentication.

Cisco UCS Manager API: Utilizes XML format and relies on session cookies for authentication.

References:

Cisco Intersight API Documentation

Cisco UCS Manager API 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 Python script provided makes a GET request to the Cisco DNA Center API to retrieve a list of network devices. The script processes the JSON response, iterates over each item in the response, and prints the hostname and management IP address of each device.

The process_devices function constructs the API URL using the dnac['host'].

It sends an HTTP GET request with the necessary headers, including the authentication token.

The response is parsed as JSON and stored in the data variable.

The script then loops through the data['response'] list, printing the hostname and managementIpAddress for each device.

In the context of webhooks, an application that interacts with a webhook can be described as a Listener or Receiver:

Listener: The application waits for incoming HTTP POST requests sent by the webhook.

Receiver: The application receives the data payloads from the webhook when certain events occur.

In test-driven development (TDD), the "green bar" refers to the visual indication that all tests have passed, typically seen in a testing framework. Two of the patterns that developers use to reach the green bar in TDD are "triangulate" and "fake it."

A. another test - This is not a green bar pattern; it's a step in the TDD cycle but not a pattern for passing tests. B. break - This is not a TDD pattern. C. triangulate - Correct. Triangulation involves adding another test to force the implementation to be more generic and robust. D. starter test - This is not a TDD pattern. E. fake it - Correct. Faking it means to return a simple, hard-coded value to make the test pass.

References:

Test-Driven Development (TDD) Patterns

Growing Object-Oriented Software, Guided by Tests

A load balancer distributes incoming network traffic across multiple servers to ensure that no single server bears too much load. This helps in balancing the traffic load, improving performance, and enhancing the availability of the applications hosted on the servers.

HTTP status codes in the 2xx range indicate that a request has been received, understood, and processed successfully.

A. 2xx - Correct. This range of status codes indicates successful responses. B. 3xx - Incorrect. This range of status codes indicates redirection messages. C. 4xx - Incorrect. This range of status codes indicates client errors. D. 5xx - Incorrect. This range of status codes indicates server errors.

References:

HTTP Status Codes

Synchronous API requests and asynchronous API requests differ primarily in how and when the client receives a response from the server.

Synchronous API Request: In a synchronous API call, the client sends a request to the server and waits for a response. The client is blocked during this time, meaning it cannot perform other tasks until the server responds. The key characteristic is that the client is able to access the results immediately after the request is processed. This is suitable for operations that need an immediate response and where the processing time is relatively short.

Asynchronous API Request: In an asynchronous API call, the client sends a request and continues its process without waiting for the server to respond. The server processes the request and sends the response back to the client at a later time. The client might receive a task ID (option A), subscribe to a webhook (option B), or poll for status (option D) to check when the operation is complete.

Refactoring is done during test-driven development (TDD) to improve the maintainability and readability of the code. After writing tests and ensuring that the code passes those tests, developers refactor to clean up the code, making it more efficient and easier to understand without changing its functionality.

A. to enable larger objects and longer methods - Incorrect. Refactoring aims to simplify and streamline code, not make it larger or more complex. B. to improve maintainability and readability - Correct. Refactoring makes the code easier to maintain and understand. C. to ensure that the previous uses of the objects are explained - Incorrect. This is not the purpose of refactoring. D. to ensure the duplication of essential code - Incorrect. Refactoring seeks to reduce code duplication, not ensure it.

References:

Test-Driven Development by Example

To complete the get_auth_token() function in the script to obtain a valid authentication token using HTTP Basic Authentication, you need to use the requests library correctly. The correct approach involves using the requests.post() method with the HTTPBasicAuth function.

A. resp = requests.post(url, auth=HTTPBasicAuth(DNAC_USER, DNAC_PASSWORD)) token = resp.json()['Token'] return token

Correct. This option uses requests.post() and HTTPBasicAuth properly. It retrieves the token from the JSON response.

B. resp = requests.post(url, auth=(DNAC_USER, DNAC_PASSWORD)) token = resp.json()['Token'] return token

Incorrect. This option incorrectly passes the auth credentials as a tuple without HTTPBasicAuth.

C. resp = http.post(url, auth=HTTPBasicAuth(DNAC_USER, DNAC_PASSWORD)) token = resp.json()['Token'] return token

Incorrect. http is not a valid method from the requests library.

D. resp = http.post(url, auth=(DNAC_USER, DNAC_PASSWORD)) token = resp.json()['Token'] return token

Incorrect. This option uses http.post(), which is incorrect.

References:

requests - HTTP for Humans

Cisco DNA Center Platform

The Dockerfile shown in the exhibit sets up an NGINX container with a delay before starting the NGINX service. It uses the ENTRYPOINT and CMD directives to define the commands that should be executed when the container starts.

ARG and ENV: These lines define and set an argument and environment variable for the delay.

ENTRYPOINT: Specifies the executable to run, in this case, /bin/sh.

CMD: Provides additional arguments to the ENTRYPOINT, which are -c and the command string to execute.

The combined command that will be executed is: /bin/sh -c "/bin/sleep 30 && nginx -g 'daemon off;'"

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 Bash script performs the following steps within the loop:

Reads each line from sites.txt.

Copies template.conf to a new file in the /etc/nginx/sites-available directory for each site.

Creates a symbolic link to the new file in the /etc/nginx/sites-enabled directory.

Changes the ownership of the new files to www-data.

This process creates a configuration file for each site, creates a link to enable the site, and ensures the correct permissions.

An IP (Internet Protocol) address is a unique identifier assigned to each device connected to a network that uses the IP for communication. It serves two main functions: identifying the host or network interface and providing the location of the host in the network. This unique ID allows devices to locate and communicate with each other over an IP-based network, ensuring that data sent across the network reaches the correct destination.

References:

Cisco DevNet Associate Study Guide: IP Addressing (Chapter 4, Section: IP Addressing and Subnetting).

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.

The difference between YAML and JSON in terms of data structure representation is that YAML uses indentation to indicate structure, while JSON uses brackets and braces.

A. YAML uses spaces; JSON uses parentheses - Incorrect. JSON does not use parentheses. B. YAML uses indentation; JSON uses brackets and braces - Correct. YAML relies on indentation for structure, whereas JSON uses brackets and braces. C. YAML uses brackets and braces; JSON uses indentation - Incorrect. This is the opposite of the correct statement. D. YAML uses parentheses; JSON uses spaces - Incorrect. Neither format uses these exclusively.

References:

YAML vs. JSON

In the provided sequence diagram, each call must complete before the next one can proceed, indicating that the calls are synchronous. Synchronous calls block further execution until the response is received, maintaining a sequential order of operations.

Synchronous Nature: The diagram shows each function call being made and then waiting for a callback before proceeding to the next step.

Blocking Behavior: Each interaction completes fully before the next one starts, which is characteristic of synchronous operations.

Option C correctly identifies that all the calls shown in the sequence diagram are synchronous.

NETCONF (Network Configuration Protocol) allows for the exchange of configuration data and state information between a network device and a management system using XML-encoded messages over a secure SSH connection.

A. allows Python scripts to be executed externally from a network device - Incorrect. This is not a capability of NETCONF. B. uses JSON to encode data in its content layer - Incorrect. NETCONF uses XML for encoding data. C. allows XML messages to be exchanged via the SSH protocol - Correct. NETCONF uses XML to encode configuration data and state information, and it uses SSH as the transport protocol. D. exposes a web-based interface - Incorrect. NETCONF itself does not provide a web-based interface; it operates over SSH.

References:

NETCONF Protocol

The exhibit shows an example of cross-site scripting (XSS), a security vulnerability where an attacker injects malicious scripts into content from otherwise trusted websites. In this case, the alert function is used to demonstrate the potential for XSS attacks, where user input is improperly sanitized, allowing script execution.

The EXPOSE instruction in a Dockerfile informs Docker that the container listens on the specified network ports at runtime. This does not publish the ports to the host machine, but it allows them to be connected to from other containers.

A. Local port 8080 of the container that launched with this docker image is accessible from co-hosted containers and external clients - Incorrect. The EXPOSE instruction does not make the port accessible to external clients. B. Local port 8080 is not reachable at all because no IP address is specified along with the EXPOSE command of the Dockerfile - Incorrect. The EXPOSE instruction does not require an IP address. C. Local port 8080 is accessible from other containers running on the same docker host as the container that launched with this docker image - Correct. The EXPOSE instruction makes the port available for inter-container communication. D. Local port 8080 of the container that launched with this docker image is accessible to external clients - Incorrect. The EXPOSE instruction does not publish the port to external clients.

References:

Dockerfile reference - EXPOSE

VLANs (Virtual Local Area Networks) provide multiple benefits, including segmenting the broadcast domain, which reduces unnecessary traffic and improves network performance. They also enable the logical grouping of devices across different physical Layer 2 switches, enhancing network management and security by isolating traffic between different VLANs.

References:

Cisco DevNet Associate Study Guide: Network Segmentation and VLANs (Chapter 4, Section: Understanding VLANs and Their Benefits).

Top of Form

Bottom of Form

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.

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.

To determine the correct JSON snippet for configuring a new interface according to the YANG model, we need to carefully examine both the YANG model definitions and the provided JSON snippets. Here’s a step-by-step explanation:

YANG Model Analysis:

The ietf-interfaces YANG module defines a container interfaces with a list interface.

Each interface has the following important leaves: name, enabled, and description.

The ietf-ip YANG module augments the interface list with a container ipv4, which includes a list address. Each address has the ip and netmask leaves.

Key Elements in JSON:

To configure an interface, the JSON must include the name of the interface, its enabled status, and the IP address configuration.

The structure should reflect the hierarchy defined by the YANG models.

Options Analysis:

Option A:

json

Copy code

"ietf-interfaces:interface": {

"name": "Loopback100",

"enabled": true,

"ietf-ip:ipv4": {

"address": [

{

"ip": "10.255.254.1",

"netmask": "255.255.255.0"

}

]

}

}

This option correctly follows the hierarchy specified in the YANG model. The interface includes name and enabled leaves and augments with ietf-ip:ipv4 which includes the address list with ip and netmask.

Option B:

"ietf-interfaces": {

"interface": {

"name": "Loopback100",

"enabled": true,

"ietf-ip": {

"ipv4": {

"address": [

{

"ip": "10.255.254.1",

"netmask": "255.255.255.0"

}

]

}

}

}

}

This option incorrectly nests interface directly under ietf-interfaces, which does not match the YANG model’s structure.

Option C:

"interface": {

"name": "Loopback100",

"enabled": true,

"ipv4": {

"address": [

{

"ip": "10.255.254.1",

"netmask": "255.255.255.0"

}

]

}

}

This option misses the namespace prefixes ietf-interfaces and ietf-ip required by the YANG model.

Option D:

"ietf-interfaces:interface": {

"name": "Loopback100",

"enabled": true,

"ietf-ip:ipv4:address": [

{

"ip": "10.255.254.1",

"netmask": "255.255.255.0"

}

]

}

This option incorrectly uses ietf-ip:ipv4:address directly, which does not align with the proper hierarchy where address should be nested inside ipv4.

Correct Explanation:

Option A correctly adheres to the YANG model hierarchy and namespace specifications.

It properly nests address within ipv4, which is itself nested within ietf-ip augmentation to interface.

This structure is consistent with how the YANG models define the relationships between the elements.

References:

Understanding of YANG models and their use: Cisco DevNet YANG Introduction

YANG Data Models in NETCONF: RFC 6020

Telnet is a protocol used for accessing remote computers over a TCP/IP network, and it runs over TCP port 23.

Telnet Protocol: Telnet allows remote command-line interface access to network devices and servers.

Port 23: The standard port for Telnet is TCP port 23.

Option D is correct as Telnet operates over TCP port 23.

For applications with significant disk I/O requirements, deploying directly on bare metal (physical servers) can provide the best performance and meet specific platform requirements.

Disk I/O Performance: Bare metal servers offer direct access to hardware resources, ensuring maximum disk I/O performance.

Automation: Modern infrastructure automation tools can fully automate the deployment, configuration, and management of bare metal servers.

Option C meets the requirements of significant disk I/O performance and full automation.

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.

The 401 Unauthorized response indicates that the API call lacks proper authentication. To authenticate a request using a Bearer token, the correct headers must be included. The "Authorization: Bearer " header is the correct format for including a Bearer token in an API request. Additionally, specifying the correct content type can also be important, but in this case, the critical headers are related to authorization.

References:

Cisco DevNet Associate Study Guide: API Authentication (Chapter 7, Section: Authentication Methods for REST APIs).

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.

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

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.

The docker build command is used to build an image from a Dockerfile. The -t option tags the image with a specified name and tag.

Tagging: The docker tag command associates an image ID with a repository and tag.

Building with Tag: The correct command to build the Docker image and tag it as local/app:0.4 is docker build -t local/app:0.4.

Option D is the correct command to build and tag the image.

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 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.

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.

In the response header shown, the "Content-Type" is specified. Response headers provide important metadata about the response, including the content type, which informs the client about the nature of the returned content (in this case, application/json).

The diff -u command shows the differences between two files. In the output provided:

Lines with + indicate additions.

Lines with - indicate deletions.

From the exhibit:

There are 8 additions (lines marked with +).

There are no deletions.

The original file was 165 lines long. Adding the 8 new lines results in a total of 173 lines.

Webhooks are user-defined HTTP callbacks triggered by specific events. They are effective in scenarios where an automated response to an event is required. For example, informing a chat channel after a deployment event or sending an email after a transaction are practical uses of webhooks. These use cases leverage the real-time capabilities of webhooks to automate responses and notifications based on events.

References:

Cisco DevNet Associate Study Guide: Event-Driven Automation (Chapter 8, Section: Webhooks and Their Use Cases).

A VLAN (Virtual Local Area Network) allows devices on one or more LANs to be grouped together as if they were on the same physical network, even if they are not.

Logical Segmentation: VLANs provide logical segmentation of networks, enabling devices to communicate as if they are on the same physical network.

Isolation and Flexibility: They offer isolation and flexibility in network design, improving security and reducing broadcast domains.

Option B is correct as VLANs create logical groupings of devices that communicate as if they are on the same physical LAN.

The error code 401 indicates an unauthorized request, which can often result from using an incorrect API endpoint. To solve this problem, ensure that the API URL correctly matches the endpoint for retrieving the device list. This URL must point to the correct API endpoint as specified by the Cisco DNA Center API documentation.

References:

Cisco DevNet Associate Study Guide: Interacting with Cisco DNA Center APIs (Chapter 7, Section: Using API Endpoints and Proper Authentication).

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

The script returns a 401 Unauthorized response, indicating that the request lacks proper authentication. To resolve this, you must include an Authorization header in the HTTP GET request. The value of this header should be the Base64 encoded string of the username and password in the format username:password. This is necessary to authenticate the request and receive a 200 OK response.

References:

Cisco DevNet Associate Study Guide: REST API Authentication Methods (Chapter 7, Section: HTTP Basic Authentication).

Cisco Umbrella provides cloud-delivered security that includes malware and content filtering through DNS. It is designed to block malicious domains, IP addresses, and URLs before they can reach your network or endpoints.

DNS-Layer Security: Cisco Umbrella uses DNS to prevent connections to known malicious sites by blocking the DNS request, thereby preventing the initiation of malicious connections.

Content Filtering: It also provides content filtering to block inappropriate or non-business-related websites based on customizable policies.

Option D is the correct answer because Cisco Umbrella is specifically known for its DNS-layer security capabilities, including malware and content filtering.

When authenticating a RESTCONF API session with a router running Cisco IOS XE Software, basic authentication is required. This involves sending a username and password encoded in Base64 as part of the HTTP headers.