200-901 DevNet Associate (DEVASC) Questions and Answers

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

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A – E, B – D, C – B, D – C, E – A, F – F

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

Infrastructure as Code (IaC) involves managing and provisioning computing infrastructure through machine-readable definition files, rather than physical hardware configuration or interactive configuration tools.

Principles of IaC:

Reusability: Complete complex systems must be built from reusable infrastructure definitions. This means infrastructure components should be modular and reusable across different environments and applications.

Consistency: Environments must be provisioned consistently using the same inputs. This ensures that every environment is set up exactly the same way, reducing the risk of errors and discrepancies.

Other Principles:

Declarative Configuration: Using a high-level language to define what the infrastructure should look like rather than how to achieve it.

Version Control: Infrastructure definitions are stored in version control systems, making changes trackable and reversible.

Incorrect Options:

C. Redeployments cause varying environment definitions: This is against IaC principles as it emphasizes consistency.

D. Service overlap is encouraged to cater for unique environment needs: This could lead to complex and unmanageable configurations.

E. Components are coupled, and definitions must be deployed for the environment to function: IaC promotes decoupled, modular components.

References:

Infrastructure as Code: IaC Principles

Solution as below

To request a service ticket using the APIC-EM REST API, the following Python script can be used:

Import necessary libraries (requests and json).

Define the APIC-EM controller's URL.

Create the payload with the username and password.

Set the header to specify the content type as JSON.

Make a POST request to the /api/v1/ticket endpoint with the payload and header.

Parse the JSON response to extract the service ticket.

References:

Cisco DevNet Associate Exam Topics: APIs and Automation (understanding how to use REST APIs)

APIC-EM API Documentation (provides details on endpoints and request structures)

1 – D, 2 – B, 3 – C, 4 – E, 5 – A

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.

Version control software offers numerous benefits to development teams. Key advantages include:

Comparisons between revisions of source code files: Version control allows developers to compare different versions of source code files, track changes, and identify what modifications were made and by whom. This is essential for debugging and maintaining code quality.

Access to current code and history for new team members: New team members can quickly get up to speed by accessing the current version of the code and the entire history of changes. This transparency facilitates onboarding and improves collaboration among team members.

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.

Cisco Advanced Malware Protection (AMP) provides APIs that can be used to obtain a list of vulnerable software on user devices. AMP for Endpoints offers extensive capabilities for threat detection and response, including the ability to query for vulnerabilities. These APIs allow developers to integrate vulnerability information into their applications, enabling proactive security measures. Detailed information on using AMP APIs can be found in the Cisco AMP for Endpoints API documentation.

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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 Ansible playbook provided in the exhibit performs the following tasks:

Uses the ios_command module to issue the show conf command on the CISCO_ROUTER_01 device.

Registers the output of the command into the variable config.

Copies the content of config.stdout[0] (the first line of the command output) to a file in /etc/ansible/configs/.

This sequence of tasks effectively backs up the running configuration of the router by capturing the current configuration output and saving it to a file.

References:

Ansible ios_command Module

Ansible Playbook Basics

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)

The HTTP status code 400 (Bad Request) is used by a REST API to indicate that the server cannot or will not process the request due to something that is perceived to be a client error (e.g., malformed request syntax, invalid request message framing, or deceptive request routing).

Virtual machines (VMs) run directly on a hypervisor, which abstracts and manages the underlying hardware resources.

Hypervisor: A hypervisor, also known as a Virtual Machine Monitor (VMM), allows multiple VMs to run on a single physical machine by providing an abstraction layer between the VMs and the hardware.

VMs: Each VM operates as a separate entity with its own operating system and applications, isolated from other VMs.

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 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.

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 Ansible script provided configures the following:

GigabitEthernet0/1 is set as a trunk port with VLANs 6-8 allowed.

GigabitEthernet0/2 and GigabitEthernet0/3 are access ports assigned to VLAN 6.

GigabitEthernet0/4 is an access port for VLAN 7.

GigabitEthernet0/5 is an access port for VLAN 8.

Thus, the correct interpretations are: B. Traffic from ports 0/2 to 0/5 can flow on port 0/1 due to the trunk. D. GigabitEthernet0/2 and GigabitEthernet0/3 are access ports for VLAN 6.

Meraki APIs offer various functionalities, including:

Retrieve live streams from a Meraki Camera (A): Meraki provides API endpoints to access live video streams from its cameras, enabling integration with custom applications.

Configure network devices via the Dashboard API (C): The Meraki Dashboard API allows for comprehensive configuration and management of Meraki network devices.

References:

Cisco Meraki API Documentation (details on the capabilities of Meraki APIs)

Cisco DevNet Associate Exam Topics: APIs and Automation (understanding how to use APIs for network configuration and monitoring)

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.

When a developer encounters many lines of code doing repetitive tasks, refactoring the code to use functions is a standard practice. This reduces code duplication and enhances readability and maintainability. Functions encapsulate repetitive logic, making the code cleaner and more organized.

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.

1 – D, 2 – A, 3 – H, 4 – F, 5 – G, 6 – E, 7 – C, 8 – B

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.

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.

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

1 – D, 2 – C, 3 – A, 4 – B

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.

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

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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

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.

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 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.

The primary function of the default gateway in a network is to forward traffic to different subnets. It acts as an intermediary that routes traffic from a local network to other networks, including the Internet.

Default Gateway: A router or network device that routes traffic from a local subnet to other subnets or networks. It serves as an access point or IP router that a networked computer uses to send information to a computer in another subnet or network.

References: Cisco DevNet Associate Certification Guide, Chapter on Networking Basics and IP Routing.

The YANG structure shown defines a leaf IPPeer that can be either an IPv4 address or an IPv6 address. The third JSON example correctly represents this union type by using an array with both possible types included:

"IPPeer": [

"10.1.1.1",

"2001:db::1"

]

}

This correctly reflects the YANG definition, where IPPeer can be either type specified in the union.

References:

YANG - Data Modeling Language

Cisco YANG Models

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

Network programmability allows for automated, scalable, and replicable network provisioning and management. This reduces the need for manual configuration, minimizes human errors, and enables the implementation of consistent network policies across multiple devices and environments. By leveraging APIs and automation tools, network operations become more efficient and can easily adapt to changes in the network.

To start a new branch in Git for developing a fix, the git checkout -b my-bug-fix command is used. This command creates a new branch called "my-bug-fix" and checks it out in one step, allowing you to start working on it immediately.

git checkout -b my-bug-fix combines the creation of the branch (git branch my-bug-fix) and switching to it (git checkout my-bug-fix) into a single command.

References:

Git Branching Basics

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 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.

Option A correctly creates a handle instance using the UcsHandle class from the UCS SDK in Python. The correct instantiation requires providing the IP address, username, password, port number, and secure connection parameters as per the documented API.

The correct code snippet is:

from ucsmsdk.ucshandle import UcsHandle

handle = UcsHandle("10.1.2.254", "admin", "password", port="443", secure=True)

This snippet matches the API documentation requirements:

ip: The IP or hostname of the UCS Server.

username: The username as configured on the UCS Server.

password: The password as configured on the UCS Server.

port: The port number to be used during the connection.

secure: True for a secure connection.

References:

UCS Python SDK Documentation (provides details on how to use UcsHandle)

Cisco DevNet Associate Exam Topics: Infrastructure and Automation (understanding how to use APIs and SDKs for automation)

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Cisco Firepower has an API that allows the capability to obtain a list of vulnerable software on user devices. Firepower Management Center (FMC) provides APIs for vulnerability management and allows security teams to query and analyze the vulnerabilities detected on endpoints and network devices.

A 401 error indicates unauthorized access. To fix this, the script needs to include the appropriate authorization token in the request headers.

Authorization Header: The Authorization header with a Bearer token is commonly used for OAuth 2.0 authorization.

Bearer Token: This token is used to authenticate API requests securely.

Option A is correct as adding the Authorization header with the Bearer token is the proper way to authenticate the request and resolve the 401 error.

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

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

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

The principle that best describes the DevOps practice outlined in the question is "end-to-end responsibility". In DevOps, teams are responsible for the entire lifecycle of the application, including development, deployment, continuous integration/continuous delivery (CI/CD), monitoring, and performance improvements. This holistic approach ensures that the same team manages all aspects of the application's lifecycle, leading to better collaboration, faster deployment cycles, and improved overall quality and reliability of the software.

References:

Cisco DevNet Associate Certification Guide

DevOps Handbook: How to Create World-Class Agility, Reliability, & Security in Technology Organizations

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

In this scenario, the developer is retrieving a large number of messages from a Cisco Webex space, and the server only sends a subset of the total messages at a time. This is an example of pagination, where the data is split into multiple pages or chunks, and the client must make additional requests to retrieve the next set of data.

Pagination: This is a common API constraint used to handle large datasets by breaking them into manageable pages.

Subsequent Requests: The client needs to send subsequent requests to get the remaining data.

Option C is correct as it describes the constraint where data is divided into multiple pages and requires additional requests to retrieve all data.

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

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

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

To retrieve a list of hosts using the Cisco DNA Center API, the provided Python script needs to be completed with the appropriate code snippets. Here's how the final script looks:

import json, requests, urllib3

from requests.auth import HTTPBasicAuth

from config import host, username, password

headers = { 'Content-Type': "application/json", 'x-auth-token': "csd0934rjxx" }

def dna_api_auth(host, username, password):

url = "https://{}/dna/system/api/v1/auth/token ".format(host)

response = requests.post(url, auth=HTTPBasicAuth(username, password), headers=headers, verify=False)

token = response.json()["Token"]

return token

def list_dna_devices(token):

url = "https://{}/dna/intent/api/v1/network-device ".format(host)

headers["x-auth-token"] = token

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

data = response.json()

for item in data['response']:

print(item["hostname"])

token = dna_api_auth(host, username, password)

list_dna_devices(token)

application/json: This is used to set the content type for the headers.

token = response.json()["Token"]: This extracts the authentication token from the response.

data['response']: This accesses the 'response' part of the JSON data returned by the API.

token: This passes the token to the headers for authorization.

json(): This parses the response to JSON format.

for item in data['response']: This loops through each item in the response data.

hostname: This prints the hostname of each device.

References:

Cisco DNA Center Platform: Cisco DNA Center Platform

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

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.

YAML and JSON are both data serialization formats often used in configuration files. One of the key differences is that YAML supports comments, whereas JSON does not.

Comments: YAML allows comments, which makes it easier to add explanatory notes within the configuration files.

Data Representation: Both formats are used to represent data structures, but YAML is often considered more human-readable.

Option B is correct as it highlights the difference that YAML supports comments while JSON does not.

The HTTP status code 201 (Created) indicates that a request has been fulfilled and resulted in a new resource being created.

201 Created: This status code is used when a new resource is successfully created as a result of a POST request.

Use Case: Commonly returned in response to a POST request that adds a new item to a collection.

References:

HTTP Status Codes: HTTP Status Code 201

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'}

Routers play a crucial role in networking by providing several key functions, including:

Broadcast Domain Segmentation: Routers separate broadcast domains, preventing broadcast traffic from one network segment from spreading to another. This improves network efficiency and reduces unnecessary traffic.

Routing: Routers forward packets between different networks based on IP addresses, enabling communication between devices on different subnets or networks.

Network Address Translation (NAT): Routers can perform NAT, which allows multiple devices on a local network to share a single public IP address.

References:

Cisco DevNet Associate Certification Guide

Cisco Router Functions

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.

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 exhibit shows an architecture where each application runs in its own isolated environment with its own OS. This setup is typical of virtual machines (VMs), where multiple VMs can run on a single physical server managed by a hypervisor.

Isolation: VMs provide complete isolation between applications, including independent operating systems.

Resource Allocation: Resources such as CPU, memory, and storage can be allocated based on deployment requirements.

Option B is correct as the type of deployment used is virtual machines.

Cisco Modeling Labs (CML) is a network simulation tool that allows users to create, configure, and simulate networks with Cisco devices and topologies.

Cisco Modeling Labs (CML): CML provides a virtual environment where users can simulate network topologies and devices, including routers, switches, and other network components.

Simulation and Testing: CML allows users to test configurations, troubleshoot network issues, and study network behavior in a controlled environment.

References:

Cisco Modeling Labs: Cisco Modeling Labs

Cisco SD-WAN (Software-Defined Wide Area Network) is a solution designed to optimize and secure connectivity across various networks. It provides several advantages including cost reduction from MPLS (Multiprotocol Label Switching), improved application performance by leveraging multiple types of connections (broadband, LTE, etc.), and simplified operations through centralized management.

Cost Reduction from MPLS: Cisco SD-WAN allows enterprises to utilize less expensive broadband internet connections alongside MPLS. This hybrid approach reduces dependency on costly MPLS circuits, significantly lowering WAN costs.

Improved Application Performance: By using application-aware routing, SD-WAN directs traffic across the best available path, ensuring better performance for critical applications.

Simplified Operations: Cisco SD-WAN centralizes network management and policy implementation, simplifying network operations and reducing the complexity associated with traditional WANs.

References:

Cisco SD-WAN Documentation: Cisco SD-WAN

The primary purpose of grouping devices in a VLAN (Virtual Local Area Network) is to segment a network such that devices within the same VLAN can communicate as if they are on the same physical network, regardless of their actual physical location. This allows for logical grouping of devices, providing improved network management and security.

An ICMP "time exceeded in-transit" message indicates that the TTL (Time to Live) of a packet has expired. The TTL value is a counter that decreases by one each time the packet passes through a router. When the TTL reaches zero, the packet is discarded, and an ICMP "time exceeded" message is sent back to the sender. This typically happens when the packet takes too many hops or the destination is too far away, causing the TTL to expire before reaching the destination.

When creating an API to interact with Cisco Meraki MV cameras, the request header must specify the correct content type to ensure the server understands the format of the request data. Setting the Content-Type header to "application/json" indicates that the request body is formatted as JSON. This is essential for APIs that expect JSON data for requests and responses.

Additionally, the API must be scheduled to run automatically at 6 p.m. every day. This can be achieved using a cron job or a scheduling tool like cron in Unix-based systems or Task Scheduler in Windows.

References:

Cisco DevNet Associate Certification Guide

Cisco Meraki API Documentation

synchronous: Code execution must wait for an API call to return before continuing.

asynchronous: Code execution does not need to wait for an API call to return before continuing.

REST: Data is called indirectly using generic HTTP methods such as GET, POST, PUT, and DELETE.

RPC: Calls to request a service from a remote server must execute the same way as a request to the local system.

Comprehensive Detailed Step by Step Explanation with References

Synchronous:

Explanation: In a synchronous API call, the client must wait for the server to process the request and return a response before it can proceed with further execution.

Mapping: "Code execution must wait for an API call to return before continuing."

Asynchronous:

Explanation: In an asynchronous API call, the client can continue processing other tasks while waiting for the server to respond. This improves the efficiency and responsiveness of the application.

Mapping: "Code execution does not need to wait for an API call to return before continuing."

REST (Representational State Transfer):

Explanation: REST is an architectural style for designing networked applications. It relies on a stateless, client-server communication protocol, typically HTTP. RESTful APIs use standard HTTP methods (GET, POST, PUT, DELETE) to perform operations on resources.

Mapping: "Data is called indirectly using generic HTTP methods such as GET, POST, PUT, and DELETE."

RPC (Remote Procedure Call):

Explanation: RPC is a protocol that one program can use to request a service from a program located on another computer in a network. The calls are made in the same way as a local function call.

Mapping: "Calls to request a service from a remote server must execute the same way as a request to the local system."

References:

Cisco DevNet Associate Certification Guide, Sections on API styles and their characteristics

Official Cisco documentation on RESTful and RPC APIs

General programming resources on synchronous vs. asynchronous API calls

Therefore, the correct mapping is:

synchronous → "Code execution must wait for an API call to return before continuing."

asynchronous → "Code execution does not need to wait for an API call to return before continuing."

REST → "Data is called indirectly using generic HTTP methods such as GET, POST, PUT, and DELETE."

RPC → "Calls to request a service from a remote server must execute the same way as a request to the local system."

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 command git branch -D test forcefully deletes the local branch named test, even if it has unmerged changes.

Deleting Branches: git branch -D is used to delete a branch forcefully.

Force Deletion: The -D flag forcefully deletes the branch regardless of its merge status.

Option C correctly describes the action of the command, which is to delete the test branch.

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

Device-level management allows for more granular control over the specific settings and configurations of individual network devices. This is beneficial in scenarios where fine-tuning of device settings is required, and where certain configurations may not be exposed or supported by the overarching controller. Controller-level management, on the other hand, abstracts many device-specific settings to provide a more uniform and simplified management interface, which may not support all the detailed configurations available at the device level.

References:

Cisco DevNet: Device vs. Controller Management

In YANG, a "container" is a grouping of related nodes and sub-nodes. The "interfaces" object in the YANG model is a container for interface-related data.

Container: The container statement is used to define an interior data node in the YANG data tree.

Structure: The exhibit shows that "interfaces" encapsulates other nodes such as interface, name, description, etc., indicating that it is a container.

References:

YANG Data Modeling Language: YANG RFC

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

In Test-Driven Development (TDD), the process starts with writing tests before writing the actual code. The primary purpose of running tests before writing the code is to ensure that the tests fail initially. This failure demonstrates that the tests are correctly identifying the absence of the desired functionality or the presence of bugs. Once the tests are verified to fail for the expected reasons, the developer then writes the minimal code necessary to pass the tests, ensuring that the new functionality works as intended and that the codebase is continuously tested.

References:

Test-Driven Development by Example

Cisco DevNet Associate Certification Guide

The first stage of a CI/CD (Continuous Integration/Continuous Deployment) pipeline typically involves developers committing and pushing code into a version control system (VCS) such as Git. This stage sets the foundation for subsequent automated processes.

Version Control System (VCS): A VCS allows multiple developers to work on code simultaneously, track changes, and manage versions.

Initial Commit: The act of committing code means saving changes to the local repository.

Push to Repository: Pushing code sends the committed changes to a remote repository, making them available for the CI/CD pipeline to trigger automated processes such as building and testing.

References:

Continuous Integration Fundamentals: CI/CD Overview

The unified diff format is used to display differences between two files. The content of the file2.py file shows the added lines in the comparison.

Unified Diff Format: The format uses + to indicate lines added in file2.py and - to indicate lines removed.

Line Addition: Line 93 of file2.py has the 'DEVICE-STATS' line, as indicated by the + symbol in the diff output.

References:

Understanding Unified Diff Format: Unified Diff

In the provided NETCONF response:

The OSPF configuration is defined by the ietf-ospf module.

The element is structured as a list, allowing for multiple routing protocol entries.

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.

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.

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.

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 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

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.

Organizing code into modules helps manage large and complex systems by breaking them down into smaller, more manageable pieces. Each module can be developed, tested, and maintained independently, which simplifies the overall development and maintenance process.

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 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).

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

To create a running container based on a tagged Docker image with the container port 8080 bound to port 80 on the host, you use the docker run command with the -p flag.

A. docker build -p 8080:80 alpine

- Incorrect. docker build is used to build an image, not run a container. B. docker exec -p 8080:80 alpine

- Incorrect. docker exec is used to run a command in a running container. C. docker start -p 8080:80 alpine

- Incorrect. docker start starts a stopped container but does not create one. D. docker run -p 8080:80 alpine

- Correct. This command runs a new container from the image and maps the ports.

References:

Docker Run Command

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

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

To restrict access to the management interface of devices using SSH and HTTPS, the correct ports need to be included in the ACLs.

Port 22: Used by SSH (Secure Shell) for secure remote login and command execution.

Port 443: Used by HTTPS (Hypertext Transfer Protocol Secure) for secure web traffic.

Options A and D are correct as they are the standard ports for SSH and HTTPS.

A MAC address (Media Access Control address) is a unique hardware address assigned to the network interface of a device. It is used for network communication at the data link layer of the OSI model.

A. unique network address that identifies the network interface of a device - Incorrect. This describes an IP address. B. unique network interface address that is provided by the DHCP server - Incorrect. MAC addresses are hardware-based, not provided by DHCP. C. unique hardware address that identifies the network interface of a device - Correct. This is the correct definition of a MAC address. D. unique hardware interface address that is provided by the central switch - Incorrect. MAC addresses are not provided by switches.

References:

Cisco MAC Address Basics

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 first three pairs of digits in a MAC address, also known as the Organizationally Unique Identifier (OUI), identify the vendor or manufacturer of the network card or adapter. This part of the MAC address is assigned by the IEEE to the manufacturers, ensuring that each MAC address is unique.

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).

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).

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.

Organizing code into modules allows for code reuse, which simplifies maintenance and improves efficiency. Modules encapsulate specific functionality, making it easier to manage and update. This approach reduces redundancy, as common functions can be written once and reused across multiple programs, leading to more manageable and maintainable codebases.

References:

Cisco DevNet Associate Study Guide: Software Development and Design (Chapter 3, Section: Modular Programming and Code Reuse).

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

A reverse proxy can be used to route external requests to different applications on the same host machine using a single public IP address and port. It forwards the requests to the appropriate backend servers based on the request URL or other routing rules.

Single Entry Point: A reverse proxy serves as a single entry point to multiple applications, making it ideal for managing traffic to multiple services hosted on the same machine.

Routing Requests: It can route requests to different internal ports based on the requested URL or other criteria.

Option A is the correct choice as a reverse proxy handles external access to multiple applications on the same host.

The exhibit shows a unified diff output, which indicates changes made to files in a version control system (e.g., git). The files being edited are indicated by the diff --git lines.

Identifying Files: The diff output shows changes to two files:

ciscoaxl/axl.py: Indicated by the line diff --git a/ciscoaxl/axl.py b/ciscoaxl/axl.py.

setup.py: Indicated by the line diff --git a/setup.py b/setup.py.

Unified Diff Format: The format includes the file paths, lines added (+), and lines removed (-).

Options B and D are the correct answers as they correspond to the files setup.py and ciscoaxl/axl.py.

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 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;'"

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'.

Using functions in code improves the development process by enabling faster code development. Functions help modularize the code, making it easier to manage, reuse, and debug, which speeds up the development process.

A. better user experience in the end product - Incorrect. This is not directly related to the use of functions in code. B. improves code performance - Incorrect. While functions can sometimes improve performance, the primary benefit is modularity and reuse. C. easier to compile the code - Incorrect. Functions do not inherently make the code easier to compile. D. faster code development - Correct. Functions make development faster by allowing code reuse and simplifying debugging.

References:

Cisco Programming Fundamentals

In the provided Python script, database credentials (DB_USER, DB_PWD) are stored in a JSON configuration file (config.json). While it is common to store configuration and credentials in external files, they should always be encrypted to ensure security.

Secret Management: Storing secrets such as database credentials directly in configuration files in plaintext is a security risk.

Encryption: Secrets must be encrypted to protect them from unauthorized access. This can be achieved using various methods such as encrypting the configuration file itself or using secret management tools.

Best Practices: Always ensure that sensitive information like passwords is encrypted when stored, especially in files that might be part of the source code.

Option C is the correct answer because it emphasizes the necessity of encrypting secrets if they are stored in the user database or configuration files to prevent unauthorized access.

When an IP packet does not match any routes in the routing table, it is routed to the default gateway. The default gateway serves as a forwarding host that routes traffic from a local network to other networks or the Internet.

A. firewall - Incorrect. A firewall is a security device, not used for routing unmatched packets. B. load balancer - Incorrect. A load balancer distributes network or application traffic across multiple servers, not used for routing unmatched packets. C. central switch - Incorrect. A switch operates at the data link layer and does not perform IP routing. D. default gateway - Correct. The default gateway is used to route packets that do not match any other route in the routing table.

References:

Cisco Network Fundamentals

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).

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

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.

In JSON (JavaScript Object Notation), data structures are represented using arrays and objects. A Python Tuple, which is an ordered and immutable collection of items, is best represented by a JSON array. JSON arrays are ordered lists of values, making them the closest equivalent to Python Tuples.

Object: In JSON, an object is a collection of key/value pairs.

Array: In JSON, an array is an ordered list of values.

Dict: In Python, a dict (dictionary) is a collection of key/value pairs.

Collection: General term for a group of items.

Thus, a Python Tuple would be represented as a JSON array.

Common data formats like JSON and YAML are typically parsed into a Python dictionary. This is because dictionaries in Python provide a way to store data in key-value pairs, which is similar to the structure of these data formats.

A. sequence - Incorrect. This is a general term that includes lists, tuples, etc. B. set - Incorrect. A set is an unordered collection of unique elements, which is not suitable for key-value pairs. C. dictionary - Correct. Dictionaries are used to store data in key-value pairs. D. list - Incorrect. Lists are ordered collections of items, which are not suitable for key-value pairs.

References:

Python Data Structures

JSON and YAML Parsing

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

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

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).

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.

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).

The error in the Python code is due to the requests library not being defined, which typically means it hasn't been installed. To resolve this issue, the requests library needs to be installed using the pip install requests command. This will add the necessary module to the Python environment, allowing the code to execute correctly.