Free and Premium Cisco 200-901 Dumps Questions Answers

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

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.

Docker-based applications offer several security benefits:

Easier to Patch: Docker containers include only the dependencies required by the application, making it easier to identify and patch vulnerabilities. This minimizes the attack surface and simplifies the management of security updates.

Separation of Applications: Docker containers enable the separation of applications that traditionally run on the same host. This isolation improves security by reducing the risk of one compromised application affecting others on the same host.

References:

Cisco DevNet Associate Exam Topics: Software Development and Design (understand containerization and its benefits)

Docker Security Best Practices (explains the security benefits of using Docker containers)

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.

Check below the answer exact.

A hybrid cloud solution is best suited for a company that wants to use on-premise infrastructure while also leveraging user self-service and scalability features of the cloud.

Hybrid Cloud:

Definition: A hybrid cloud combines on-premise infrastructure (private cloud) with public cloud services, allowing data and applications to be shared between them.

Scalability: Hybrid cloud allows for the flexibility to scale resources up or down as needed. When demand exceeds the capacity of the on-premise infrastructure, additional resources from the public cloud can be utilized.

Self-Service: Users can provision and manage resources without IT intervention, typically through a self-service portal.

Use Cases: This is ideal for businesses that need to maintain control over certain data and applications while taking advantage of the scalability and cost-efficiency of the public cloud.

Other Cloud Types:

Public Cloud: Fully managed by third-party providers and shared among multiple organizations. It offers high scalability but may have concerns about data privacy and control.

Private Cloud: Exclusively used by one organization, providing more control and security but may be limited in scalability compared to public cloud.

Multi-Cloud: Use of multiple cloud services from different providers, which can be complex to manage but provides flexibility and redundancy.

References:

Cisco Cloud Solutions: Hybrid Cloud Solutions

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.

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.

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

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.

A 401 Unauthorized error indicates that the request has not been applied because it lacks valid authentication credentials for the target resource. To resolve this error when making an HTTP GET request to retrieve data using RESTCONF on a CSR 1000V, you need to ensure that the correct authentication credentials (username and password) are provided.

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

Edge computing is a distributed computing paradigm that brings computation and data storage closer to the sources of data. This helps to:

Reduce Latency: By processing data closer to where it is generated, edge computing reduces the time taken for data to travel to a central server and back. This is especially important for applications requiring real-time or near-real-time responses.

Optimize Bandwidth: Reducing the amount of data sent to a central data center can conserve bandwidth and lower costs.

Enhance Security and Privacy: Processing data locally can enhance security and privacy by minimizing the exposure of data during transmission.

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.

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 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.

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.

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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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.

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.

 Understand the JSON Structure: The JSON data given in the exhibit consists of an array of objects. Each object has a type and an items key. The items key contains an array of objects, each with a color and another items key, which is an array of strings representing items of that color.

 Analyze the Python Code: The Python code provided is:

print(filter(lambda l: l['type'] == 'fruit', vegetables)[0]['items'][0]['items'][0])

Break Down the Code:

filter(lambda l: l['type'] == 'fruit', vegetables): This line filters the JSON array vegetables to include only objects where the type is 'fruit'.

filter(...)[0]: After filtering, this selects the first object in the filtered list, which is the fruit object.

['items'][0]: This accesses the first item in the items array of the fruit object. In this case, it refers to the object where color is "green".

['items'][0]: This accesses the first item in the items array of the green object, which is "kiwi".

Evaluate the Code:

The first object of type fruit in the JSON is found.

The first item in the items array for fruit with the color green is selected.

The first item in this nested items array is "kiwi".

Therefore, the output of the given Python command is "Kiwi".

References:

Python documentation on filter: Python Docs - Filter

JSON structure understanding from DevNet Associate study materials on API interactions and data parsing.

When a REST API limits the amount of data returned in a response, it often uses pagination. Pagination breaks the response into smaller, more manageable chunks, allowing the client to retrieve the data in multiple requests.

Pagination: Limits the number of records returned in a single response, requiring additional requests to retrieve subsequent records.

Payload limit: Restricts the size of the response payload but is not the specific feature for controlling record count.

Rate limiting: Controls the number of requests a client can make in a given time period.

Service timeouts: Define how long the server will wait for a request to complete before timing out.

git add .

git commit -m “this is my edit”

git push

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

OR

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.

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

A platform that runs directly using a hypervisor is referred to as a virtual machine (VM). A hypervisor, also known as a virtual machine monitor (VMM), is software that creates and runs VMs. It allows multiple VMs to share the hardware resources of a physical host, providing isolation and resource management for each VM.

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)

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.

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

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

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.

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.

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

10.00

9.00

8.00

20.00

<algebra>12.00</algebra>

translates to the following JSON structure:

{

"books": {

"science": {

"biology": "10.00",

"geology": "9.00",

"chemistry": "8.00"

},

"math": {

"calculus": "20.00",

"algebra": "12.00"

}

}

}

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

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

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

Option A:

json

Copy code

{

"books": {

"science": {

"biology": "10.00",

"geology": "9.00",

"chemistry": "8.00"

},

"math": {

"calculus": "20.00",

"algebra": "12.00"

}

}

}

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

Option B, C, and D:

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

References:

Converting Between XML and JSON

JSON and XML Comparison

When package updates from a local server fail but succeed from an external repository, it is often due to misconfiguration in the update utility. One common issue is that the update utility might be configured to use a proxy, which is not required or properly set up for internal resources. This misconfiguration can cause the update utility to fail in reaching the local server.

References:

Cisco DevNet Associate Exam Topics: Infrastructure and Automation (troubleshooting and configuring network and server environments)

Linux System Administration Documentation (details on configuring package managers and handling proxy settings)

Solution below as

Cisco DNA Center provides a REST API that allows users to interact with the network devices managed by the platform. To retrieve a list of network devices, an HTTP GET request is sent to the endpoint . The response from this request contains a list of network devices in JSON format. This API endpoint allows for programmatic access to network device data, facilitating automation and integration with other systems. Detailed information about the Cisco DNA Center APIs can be found in the Cisco DNA Center API documentation.

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JSON objects are indeed collections of key-value pairs, where each key is a string, and the value can be a string, number, boolean, array, or another object. JSON is often used for data interchange due to its lightweight and readable format. Reference: JSON Introduction.

The syntax of XML includes tags, elements, and attributes. XML uses a hierarchical structure with opening and closing tags to define elements, and attributes provide additional information about elements. XML is widely used for data representation and transport. Reference: XML Basics.

JSON arrays, in contrast, are ordered collections of values (not key-value pairs), and XML objects are more complex structures with elements and attributes rather than simple key-value pairs.

Cisco DNA Center is a network management and command center for enterprise networks, providing network controller-level management features. It offers capabilities such as automation, assurance, fabric provisioning, and policy-based segmentation, making it a comprehensive solution for managing and optimizing network performance and operations. Cisco DNA Center is part of the broader Cisco Digital Network Architecture (Cisco DNA), designed to facilitate the efficient and automated management of networks. More information can be found on the Cisco DNA Center product page.

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

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

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

References:

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

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

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.

Jitter refers to the variation in packet arrival times, which can cause packets to arrive out of order, leading to choppy audio or dropped parts of a conversation in real-time VoIP applications. Latency and delay refer to the time it takes for a packet to travel from source to destination, and capacity refers to the bandwidth available, but jitter specifically affects the consistency of packet delivery timing, which is critical for VoIP quality.

References:

Cisco DevNet Associate Study Guide: QoS and Network Performance (Chapter 8, Section: Understanding Jitter and Its Effects).

The primary security issue in this scenario is that API keys are stored in the configuration files. It is a best practice to store sensitive information such as API keys in a secure vault service rather than in configuration files.

A. Communication between the application and the services is not encrypted - Incorrect. The communication is through HTTPS, which is encrypted. B. The database credentials should be stored in the configuration files so that they are secured on the same server - Incorrect. Database credentials should be securely obtained, as mentioned, through a vault service. C. The API keys are stored in the configuration files but should be stored in the vault service - Correct. Storing API keys in configuration files poses a security risk. They should be stored in a secure vault service. D. The synchronization logs should be encrypted and not stored in a relational database - Incorrect. The issue is not about storing logs in a relational database, but rather the storage of API keys in configuration files.

References:

Secure Secrets Management

Best Practices for Storing API Keys

The Waterfall method is a sequential software development process where a phase begins only after the previous phase has ended. In contrast, Agile development involves iterative processes where phases run in parallel and are continuously improved upon.

A. Waterfall increases agility to implement faster while Agile promotes reliability - Incorrect. This is the opposite of the typical characteristics of these methods. B. A phase begins after the previous phase has ended in Waterfall while Agile phases run in parallel - Correct. Waterfall is linear and sequential, while Agile is iterative and parallel. C. Customers get feedback during the process in Waterfall while they can see the result at the end in Agile - Incorrect. Agile involves continuous feedback, whereas Waterfall typically provides feedback only at the end. D. Requirements can be updated in Waterfall while in Agile it should be gathered in the beginning - Incorrect. Requirements in Agile can be updated continuously, while Waterfall requires requirements to be defined upfront.

References:

Waterfall vs. Agile Methodologies

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 platform used to programmatically create a space and invite users for collaboration is Cisco Webex.

A. Cisco Intersight - Incorrect. Cisco Intersight is used for infrastructure management. B. Cisco Finesse - Incorrect. Cisco Finesse is used for contact center management. C. Cisco Webex - Correct. Cisco Webex is used for collaboration and includes APIs to create spaces and invite users. D. Cisco UCM - Incorrect. Cisco Unified Communications Manager (UCM) is used for call processing.

References:

Cisco Webex API Documentation

Cisco Webex Teams API

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

The sequence diagram shows the process where the API client first calls the /organizations endpoint to get the list of organization IDs. Then, for each organization, it makes a call to the /organizations/(orgId)/networks endpoint to retrieve the networks for that organization. Since there are two organizations, the GetAllNetworks function will make two parallel calls to the /organizations/(orgId)/networks endpoint, one for each organization.

References:

Cisco DevNet Associate Study Guide: Using Cisco Meraki APIs (Chapter 7, Section: Understanding Meraki API Calls and Endpoints).

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;'"

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 Python script uses nested loops to gather information:

The first loop checks for the "ACME" organization.

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

The second loop checks for the "BLDG21" network.

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

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

The 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.

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

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

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

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

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

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.

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

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

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

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

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.

In the test-driven development (TDD) model, after a test fails, the next step is to change the code to make the test pass. TDD involves writing a test for a new feature or functionality, running the test to see it fail, then writing the minimal amount of code necessary to pass the test, and finally refactoring the code to meet quality standards.

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 routing table on a network device serves as a map for determining the best path to route packets to their destinations. It lists all the routes to particular destinations, including both the next-hop addresses and the associated metrics. The routing table also includes static entries (manually configured routes) and dynamic entries (routes learned through routing protocols).

References:

Cisco DevNet Associate Study Guide: Understanding Routing Tables (Chapter 4, Section: Routing and Switching Fundamentals).

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

References:

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

The CALMS framework is used to assess and guide DevOps transformations. It stands for Culture, Automation, Lean, Measurement, and Sharing. Each element represents a critical area for improvement in DevOps practices.

Collaboration: Emphasizes teamwork and breaking down silos.

Lean: Focuses on eliminating waste, optimizing processes, and ensuring efficiency.

Sharing: Encourages transparency and knowledge sharing among teams.

Measurement: Involves monitoring and analyzing performance metrics to drive improvement.

Given that the team is struggling to complete releases on time due to increased overhead, targeting the Lean aspect can help streamline processes, reduce waste, and improve efficiency, ultimately helping them to meet their release deadlines.

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

References:

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

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

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

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

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

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).

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

References:

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

The Bash script 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.

The NETCONF RPC message shown in the exhibit requests the running configuration of the device filtered to show only interface names.

A. The running-config of the device is returned - Correct. The RPC message with the operation retrieves the running configuration filtered to include only the interface names. B. The name of each interface is reset to a default name - Incorrect. The RPC message is a read operation, not a configuration change. C. All the YANG capabilities supported by the device are returned - Incorrect. The RPC message specifically targets the running configuration, not the YANG capabilities. D. A list of interface names is returned - Incorrect. While the filter is for interface names, the context is that the running configuration containing these interface names is returned.

References:

NETCONF Protocol Operations

YANG Data Modeling Language

Answer: A

Top of Form

Bottom of Form

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 provided documentation outlines how to use Basic HTTP Authentication with the Cisco AMP API. The correct method involves encoding the client ID and API key in base64 format and then including them in the authorization header. However, in the given scripts, the use of the requests library’s auth parameter directly with the client ID and API key is also a valid method.

Option A correctly uses the requests library to make an API call with the client ID and API key. This method is supported and valid as per the documentation.

python

Copy code

import requests

amp_client_id = 'alb2c3d4e5f6g7h8i9j0'

amp_login_password = 'l0g1n_p@ssw0rd'

url = ' '

request = requests.get(url,

auth=(amp_client_id, amp_login_password))

print(request.json())

Client ID and API Key: amp_client_id and amp_login_password are set with the values provided.

URL: The URL for the AMP API endpoint is correctly set.

GET Request: The requests.get method is used with the auth parameter that takes a tuple of the client ID and API key.

Response: The response is printed in JSON format.

Option B:

Does not use the auth parameter or a header for Basic Authentication, thus it will fail.

Option C:

Uses a single amp_auth_token which does not follow the provided documentation method.

Option D:

Incorrectly uses the auth parameter with a concatenated client ID and API key without specifying Basic Authentication in the header.

References:

Cisco AMP for Endpoints API Documentation

Requests: Authentication

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

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.

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

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.

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

References:

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

In version control systems, code review is typically performed before the code is merged into the main branch. The code review process involves evaluating the changes, ensuring they meet the project's coding standards, and identifying potential issues. This process helps maintain code quality and integrity before integration into the larger codebase.

References:

Cisco DevNet Associate Study Guide: Version Control and Code Review (Chapter 6, Section: Best Practices for Version Control).

The HTTP client error response code accompanied by a Retry-After header typically indicates that the client has sent too many requests in a given amount of time, leading to rate limiting by the server. This is often indicated by a 429 Too Many Requests status code. The Retry-After header informs the client how long it should wait before making another request.

References:

Cisco DevNet Associate Study Guide: REST API Error Handling (Chapter 7, Section: Understanding HTTP Status Codes).

Edge computing involves processing data closer to where it is generated (the "edge" of the network) rather than sending it to a centralized data center or cloud for processing. This approach reduces latency and bandwidth usage, providing high-speed data processing capabilities. It is particularly beneficial for IoT implementations where real-time processing and response are crucial.

References:

Cisco DevNet Associate Study Guide: IoT and Edge Computing (Chapter 9, Section: Benefits of Edge Computing).

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).

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).

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.

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

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

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

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

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

References:

Python Classes and Objects - W3Schools

Python Documentation on Classes

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

Edge computing processes data locally, close to where it is generated, rather than sending it to a centralized cloud server. This approach enhances privacy control and reduces latency.

Local Processing: Sensitive data is analyzed locally on edge devices, reducing the need to transmit potentially sensitive information over the network.

Privacy Control: By keeping data processing at the edge, organizations can better comply with data privacy regulations and reduce the risk of data breaches.

Reduced Latency: Local data processing minimizes the delay associated with sending data to and from the cloud, improving real-time analysis capabilities.

References:

Edge Computing and Data Privacy: Edge Computing Benefits

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

References:

Git Documentation - git clean

Cisco DevNet Associate Certification Guide

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

For a web-based application that captures and processes credit card information, it is essential to ensure the security of the private customer data. Enabling the encryption of network traffic, typically through TLS (Transport Layer Security), protects sensitive information by encrypting data transmitted between the client and server. This prevents unauthorized access and ensures data integrity and confidentiality during the transaction process.

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.

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

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

References:

GNU Diffutils: Unified Format

A code review process involves evaluating and examining another developer's code to identify potential issues, bugs, and improvements before the code is merged into the main codebase. It helps in maintaining code quality and catching errors early in the development cycle.

Error Detection: Code reviews help detect and eliminate common mistakes and bugs that developers might overlook.

Knowledge Sharing: They promote knowledge sharing and learning among team members.

Code Quality: Ensures that the code adheres to the coding standards and best practices.

Option D is correct as the primary benefit of code reviews is to eliminate common mistakes during development.

The subnet mask is used to determine the network and host portions of an IP address. It helps in defining the size of the subnet and the range of IP addresses within that subnet.

Subnet Portion: The subnet mask identifies which part of the IP address refers to the network (subnet) portion.

Host Portion: The remaining part of the IP address after applying the subnet mask identifies the specific host within the subnet.

Options A and D are correct as they capture the details about the subnet and host portions of an IP address.

The Ansible playbook in the exhibit consists of two stages:

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

Stage 2: Starts the httpd service.

Stage 1:

- name: stage1

ansible.builtin.service:

name: network

state: restarted

args: eth0

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

Stage 2:

- name: stage2

ansible.builtin.service:

name: httpd

state: started

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

References:

Ansible Playbook Documentation: Ansible Service Module

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

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.

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

References:

Cisco DHCP Overview

RFC 2131: DHCP

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

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

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

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

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

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

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

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

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

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

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

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

References:

Cisco DevNet Associate Certification Guide

Cisco DNA Center API Documentation

CSRF (Cross-Site Request Forgery) is an attack that forces an end user to execute unwanted actions on a web application in which they are currently authenticated. It exploits the trust that a web application has in the user's browser.

Authenticated Session Exploit: CSRF takes advantage of the fact that the user is already authenticated, making the attack appear legitimate.

Unwanted Actions: The attacker tricks the user into performing actions without their knowledge.

Option D is correct as CSRF is the OWASP threat that exploits authenticated sessions to execute attacks.

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

An HTTP 502 Bad Gateway error indicates that the server acting as a gateway or proxy received an invalid response from the upstream server. This suggests there may be an issue with the configuration or availability of the server behind the load balancer.

HTTP 502 Error: This error occurs when the load balancer or gateway receives an invalid response from the backend server.

Server Configuration: The issue is likely due to misconfiguration or problems with the backend server that needs to be resolved.

Option A is correct as it identifies that the issue lies with the server configuration behind the load balancer.

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

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.

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

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

Latency refers to the delay between a client request and a server response. A large distance between a client device and a host server increases the latency due to the time it takes for data to travel over the network.

Latency: The time delay experienced in a system, particularly in networking, where it refers to the time taken for data to travel from the source to the destination.

Impact: High latency can result in slow response times, negatively impacting the performance of applications, especially those requiring real-time interactions.

References:

Network Latency Overview: Network Latency

Continuous Integration (CI) is a DevOps practice where developers frequently merge their code changes into a central repository. This practice aims to detect integration bugs as quickly as possible and improve the quality of the software. CI involves running automated tests and builds, ensuring that new code changes do not break the existing functionality. In the given scenario, the group of developers wants to deliver release-ready code and run automated tests frequently, which aligns with the principles of Continuous Integration.

References:

Atlassian - What is Continuous Integration?

Cisco DevNet Associate Certification Guide

An HTTP 404 status code indicates that the requested resource could not be found. In the context of the Cisco DNA Center API, this usually means that the URL being accessed is incorrect or the endpoint does not exist. The solution is to verify and correct the API URL to ensure it points to a valid endpoint.

Example correct API URL:

url = ' '

This ensures that the script is making requests to the correct API endpoint.

References:

Cisco DNA Center API Documentation

Cisco DevNet Associate Certification Guide

The observer pattern is designed to create a relationship where an object (subject) maintains a list of its dependents (observers) and notifies them of any state changes. This pattern achieves loose coupling between the subject and its observers, allowing them to interact without being tightly bound to each other. This flexibility ensures that changes in the subject do not heavily impact the observers, and vice versa.

The issue described indicates that HTTPS (port 443) access is not working for one specific server (172.16.50.3) in the network farm, while it works for the others. This suggests that the transport port (port 443) might be blocked or filtered for this particular server.

Transport Port Blocking: Network firewalls or security groups might block specific ports for certain IP addresses.

Server Configuration: The server might not have the necessary configuration to accept HTTPS connections on port 443.

Troubleshooting: Verifying firewall rules, security group settings, and server configurations can help identify and resolve the issue.

References:

Network Troubleshooting Guide: Troubleshooting Network Issues

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

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

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

References:

Cisco DevNet Associate Certification Guide

Cisco Ethernet Switch Operation

DNS (Domain Name System) is the technology responsible for matching a name to an IP address of an application running on a host. When a user types a domain name into a browser, DNS translates that domain name into the corresponding IP address, enabling the user's device to connect to the server hosting the application.

References:

Cisco DevNet Documentation - DNS

Cisco DevNet Associate Certification Guide

For the distributed application developed using the Cisco Intersight SDK to communicate with the Intersight API, the traffic needs to be allowed through the firewall. The correct URL and port that need to be provided to the firewall administrator are svc.intersight.com on port 443. Port 443 is the standard port for HTTPS traffic, which ensures secure communication between the application and the Intersight server.

References:

Cisco DevNet Associate Certification Guide

Cisco Intersight API Documentation

Simple Network Management Protocol (SNMP) is widely used for network management and monitoring. It allows administrators to monitor and manage network devices such as routers, switches, and servers by collecting information on device performance, status, and errors.

SNMP: Provides a framework for exchanging management information between network devices. It helps in monitoring network performance, detecting faults, and configuring devices remotely.

Other Protocols:

DHCP: Used for dynamic IP address assignment.

DNS: Resolves domain names to IP addresses.

NTP: Synchronizes time across network devices.

References:

Cisco DevNet Associate Certification Guide

Cisco SNMP Overview

When a mobile phone using 4G fails to access the application, it is likely because the application is hosted on-premises and requires VPN connectivity to access it. On-premises applications often have network restrictions for security reasons, and access from external networks (such as 4G) typically requires a secure VPN connection to ensure data security and compliance with access policies.

The pip freeze command is used to output installed packages in the current environment and their versions. The > operator redirects this output to a file, in this case, requirements.txt.

pip freeze: Outputs the list of installed packages and their versions.

Redirection: The > operator is used to redirect the output to a file.

Option B is correct as it uses the > operator to redirect the output of pip freeze to requirements.txt.

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.