200-901 Questions and Answers

A network interface hardware address, also known as a MAC (Media Access Control) address, is a unique identifier assigned to network interfaces for communications on the physical network segment.

Domain name: A human-readable address for network resources.

IP address: A logical address used for identifying devices on a network.

Workstation name: A human-readable name assigned to a computer.

MAC address: The correct answer, which is a hardware address assigned to a network interface.

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

When you execute the command git clone ssh://john@example.com/path/to/my-project_git, the git clone command is used to create a local copy of a remote repository. In this case, it is accessing the repository over SSH (Secure Shell). The URL ssh://john@example.com/path/to/my-project_git specifies the location of the remote repository.

git clone is a Git command that creates a copy of an existing repository in a new directory.

The local copy will contain all the history and branches of the original repository.

The repository will be cloned into a directory named after the remote repository, which in this case would be "my-project".

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.

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 https://DNA-c_API_ADDRESS/api/v1/network-device/ . 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.

Top of Form

Bottom of Form

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

Authorization: Basic am9objowMTlzNDU2Nzg=

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

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

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

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

Troubleshooting Steps:

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

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

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

References:

Cisco Documentation on ACLs: Access Control Lists

Cisco ICMP Overview: ICMP Messages

To delete a directory and all of its contents (including read-only files) recursively without prompting for confirmation, the rm command with the -rf flags should be used.

rm -r: This option tells rm to remove directories and their contents recursively.

rm -f: This option tells rm to force the removal of files, ignoring nonexistent files and never prompting for confirmation.

Therefore, the correct command is rm -rf old_project. This command will recursively remove the old_project directory and all its contents without any confirmation prompts, regardless of file permissions.

References: Cisco DevNet Associate Certification Guide, Chapter on Linux and Bash Commands.

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.

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.

The provided Ansible playbook is designed to connect to an IOS router and execute the "show run" command to retrieve the current running configuration. The configuration is then registered in a variable called config. The next task copies the output stored in the config variable to a file in a specified directory on the local machine. The file is named based on the router's hostname.

Here are the steps:

Define the hosts: The playbook targets the {{ router }} group or host.

Gather facts: Enabled with gather_facts: true to collect useful information about the target devices.

Connection type: Local, meaning the playbook runs on the local machine where Ansible is invoked.

Task 1 - ios_command:

Executes the "show run" command.

Uses the provided router credentials.

Registers the command output to the config variable.

Task 2 - copy:

Takes the first element from config.stdout (the output of the "show run" command).

Copies this content to a file in /etc/ansible/configs/, naming the file command_{{ router_hostname }}.txt.

Code review is typically performed before the merge of code in a version control system. This process involves examining code changes to ensure they meet the required standards, are free of bugs, and align with the project’s goals. The review usually happens after code has been committed to a feature branch but before it is merged into the main branch. This helps maintain the integrity of the main branch and ensures that any issues are caught early. More information can be found in best practices for code review.

The docker run -p 3000:5000 command maps port 3000 on the host to port 5000 on the Docker container. This means that any process on the host that wants to access the service running inside the container should connect to port 3000 on the host. The service inside the container listens on port 5000, but from the host's perspective, it will be accessed via port 3000. More information on Docker port mapping can be found in the Docker documentation.

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

To extract the value "172.16.0.11" from the given JSON data, you need to navigate through the JSON structure using the correct keys and indices. The JSON structure provided is as follows:

"items": [{

"kind": "object#NetworkObj",

"selfLink": "https://10.201.230.5/api/objects/networkobjects/db01 ",

"name": "db01",

"host": {

"kind": "IPv4Address",

"value": "172.16.0.11"

},

"objectId": "db01"

}]

}

Access the 'items' key: This gives you a list containing one object.

Access the first object in the 'items' list: Using the index [0].

Access the 'host' key: This contains the 'kind' and 'value' keys.

Access the 'value' key within the 'host' object: This gives you the required value "172.16.0.11".

Thus, the correct way to access the value "172.16.0.11" is data['items'][0]['host']['value'].

References:

JSON Parsing in Python: Python JSON Module

Cisco DevNet Documentation: DevNet JSON Handling

1 – B, 2 – D, 3 – A, 4 – C

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.

NETCONF (Network Configuration Protocol) is an IETF standard protocol used for managing network devices. By default, NETCONF operates over the SSH protocol on port 830. This default port is defined to separate NETCONF traffic from other types of SSH traffic, providing a dedicated channel for network configuration tasks.

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

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

1 – A, 2 – C, 3 – B

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.

To prepare the file README.md in the working tree for the next commit operation in Git, the command git add README.md should be used. This command stages the file, meaning it adds the file's current content to the staging area, which is a preparatory step before committing it to the repository.

git add README.md: Adds the README.md file to the staging area.

git commit README.md: Commits all staged changes (not just README.md unless it is the only file staged).

References: Pro Git book by Scott Chacon and Ben Straub, Git documentation.

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.

Top of Form

Bottom of Form

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

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

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

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

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.

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

HTTP Status Code 400 - Bad Request:

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

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

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

Other Status Codes:

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

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

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

References:

HTTP Status Codes: MDN Web Docs

RFC 7231: HTTP/1.1 Semantics and Content

DevOps emphasizes collaboration between development and operations teams, breaking down organizational silos to improve workflow and communication (C). Additionally, DevOps focuses on automating processes to increase efficiency, reduce manual effort, and minimize errors, often prioritizing automation over extensive documentation (E).

References:

Cisco DevNet Associate Exam Topics: DevOps Practices and Principles (understanding the core principles of DevOps)

"The Phoenix Project" by Gene Kim, Kevin Behr, and George Spafford (explains the importance of cross-functional teams and automation in DevOps)

git add .

git commit -m “this is my edit”

git push

1 – E, 2 – B, 3 – D, 4 – A

Statement B: One of the routers has two connected serial interfaces.

This statement is true if the diagram indicates that a router has two serial interfaces. In network diagrams, routers often have multiple interfaces to connect different segments or other routers, particularly for WAN connections.

Statement E: The subnet address of PC-B has 18 bits dedicated to the network portion.

If PC-B's subnet is represented by an address such as 192.168.x.x/18, then 18 bits are used for the network portion, leaving 14 bits for host addresses. This aligns with standard subnetting practices where a /18 subnet mask means the first 18 bits define the network, and the remaining bits define host addresses.

For example, a subnet mask of 255.255.192.0 corresponds to /18 in CIDR notation, indicating that the first 18 bits are for the network portion.

Incorrect Statements:

Statement A: PC-A and PC-B are in the same subnet.

This statement can be evaluated based on the IP addresses and subnet masks provided for PC-A and PC-B. If they share the same network portion of their addresses and subnet masks, then they are in the same subnet. However, without explicit addresses, this cannot be verified.

Statement C: The subnet of PC-C can contain 256 hosts.

For a subnet to contain 256 hosts, it would need a /24 subnet mask (255.255.255.0), which provides 256 IP addresses (254 usable for hosts). The subnet mask should be examined to determine the validity of this statement.

Statement D: R1 and R3 are in the same subnet.

This depends on the IP addresses and subnet masks assigned to the interfaces on R1 and R3. If they are within the same network range, then they would be in the same subnet.

Since the network diagram is not provided, the verification is based on common networking principles and standard practices in subnetting. For detailed and accurate confirmation, the exact IP addresses, subnet masks, and interface connections need to be reviewed.

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.

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

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).

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 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).

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

Cisco Umbrella provides DNS-layer security and can block all traffic to a domain using a single API call. This feature is particularly useful for preventing access to malicious sites and enhancing security across the network by controlling domain access.

References:

Cisco DevNet Associate Study Guide: Security with Cisco Umbrella (Chapter 8, Section: DNS-Layer Security and API Integration).

In this question, the network engineer is using the RESTCONF API to update information about device interfaces. The RESTCONF API uses the YANG data modeling language and can encode data in either XML or JSON format. The appropriate headers must be set to specify the content type and the format in which the data is expected.

RESTCONF API: This API allows network devices to be managed using web-based protocols, and it relies on the YANG data model to represent the configuration data.

Content-Type and Accept headers: These headers define the media type of the resource. The Content-Type header tells the server what type of data is being sent by the client. The Accept header indicates the type of data that the client can receive from the server.

Option A is the correct answer because it specifies the correct content type and accept headers for using XML with YANG data models in RESTCONF API calls.

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'.

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

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

References:

Git Merge Squash

The provided Ansible playbook automates the process of ensuring the nginx server is installed while removing apache2, and then updates all the packages to their latest versions.

Task 1: Ensures that apache2 is uninstalled (state: absent).

Task 2: Ensures that nginx is installed (state: present).

Task 3: Updates all packages to their latest versions (state: latest).

Option C accurately describes the process automated by the Ansible playbook.

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.

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

References:

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

The Model-View-Controller (MVC) design pattern provides several advantages, including the ability to present multiple views of the same data to different user groups and the separation of concerns by dividing the application into three interconnected components.

A. to enable multiple views of the same data to be presented to different groups of users - Correct. MVC allows different views to display the same data, enhancing flexibility and usability. B. to provide separation between the view and the model by ensuring that all logic is separated out into the controller - Correct. MVC promotes the separation of concerns, making the application easier to manage and scale. C. to ensure data consistency, which requires that changes to the view are also made to the model - Incorrect. This is not a primary advantage of MVC; changes to the view do not directly affect the model. D. to ensure that only one instance of the data model can be created - Incorrect. This is not a characteristic or advantage of MVC. E. to provide only a single view of the data to ensure consistency - Incorrect. MVC supports multiple views.

References:

MVC Design Pattern

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.

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

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.

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.

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.

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

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.

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.

An engineer writes a Python script that uses two different API calls to query Cisco DNA Center for the number of interfaces on a device. The engineer notices that the two API calls produce different results. The fewer interfaces returned for the same device when the 'get_all_interfaces' API call is used can be explained by pagination.

A. times out - Incorrect. A timeout would likely result in an error, not fewer results. B. rate limit - Incorrect. Rate limiting would slow down requests but not reduce the number of returned interfaces. C. pagination - Correct. The 'get_all_interfaces' API call might be paginated, meaning it returns results in chunks rather than all at once. D. invalid password - Incorrect. An invalid password would result in an authentication error, not fewer results.

References:

Cisco DevNet DNA Center Platform

API Pagination

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

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

SSH (Secure Shell) is a protocol that provides a secure channel over an unsecured network by using encryption. It operates over TCP port 22 and is commonly used for remote login and command execution on network devices and servers. SSH ensures secure communication between the client and server by encrypting the session.

References:

Cisco DevNet Associate Study Guide: Understanding Network Protocols (Chapter 2, Section: Common Network Protocols and Ports).

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.

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.

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 = 'https://api.amp.cisco.com/v1/version '

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

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

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

References:

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

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

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

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).

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.

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

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

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

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

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

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

References:

Dockerfile reference - EXPOSE

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

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

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

The 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).

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

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

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

Cisco Umbrella: Offers cloud security services.

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

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

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.

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

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

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

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

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

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

Model-driven programmability refers to using data models to define the desired state of network infrastructure and automate its configuration and management. This approach offers several benefits:

Infrastructure Resource Optimization: Model-driven programmability allows for more efficient use of network resources by ensuring consistent and optimal configurations. Automation driven by data models helps in reducing human errors and improving the overall performance and utilization of the infrastructure.

Consistency: Automated, model-driven configurations ensure that network devices are consistently configured, reducing variability and the risk of misconfigurations.

Scalability: It enables scalable automation solutions that can easily adapt to changing network requirements and topologies.

References:

Cisco DevNet Associate Certification Guide

Cisco Model-Driven Programmability

One of the key principles of a code review process is to ensure that naming standards are consistent. This helps maintain code readability, understandability, and maintainability. Consistent naming conventions reduce the cognitive load for developers when reading and understanding the code, making it easier to manage and less prone to errors.

References:

Atlassian - Code Review Best Practices

Cisco DevNet Associate Certification Guide

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

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

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

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

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

References:

Virtual Machines Overview: VMware VMs

The provided Bash script performs the following steps:

Adds a new user with useradd.

Adds a new group with groupadd.

Creates a directory /opt/scripts.

Copies all Python scripts (*.py) to the /opt/scripts directory.

Changes to the /opt/scripts directory.

Lists the Python scripts and processes each script in a loop.

Within the loop, the script:

Appends the script name to a file content.txt.

Assigns execution privileges to the script (chmod u+x).

Changes the ownership of the script to the newly created user and group (chown $1:$2).

This workflow automates the process of setting execution permissions for the owner (the newly created user) and assigning the user and group ownership to the scripts. It also stores the script names in content.txt.

References:

Cisco DevNet Associate Certification Guide

Bash Scripting Documentation

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

The provided RESTCONF query is configuring network interfaces using the YANG data model. Based on the JSON data:

GigabitEthernet1: This interface has an enabled status set to true and an IP address configured.

GigabitEthernet2: This interface has an enabled status set to false, which means it is being shut down.

GigabitEthernet3: This interface is also set with an enabled status of false.

The descriptions for these interfaces are also included in the configuration, so the descriptions for two interfaces (GigabitEthernet1 and GigabitEthernet2) are applied.

References:

RESTCONF and YANG Model Basics

pyATS (Python Automated Test Systems) is a comprehensive testing framework developed by Cisco, designed specifically for automating the testing of network devices. It provides a robust and flexible environment for creating and running tests on network devices and simulating network automation scenarios.

pyATS enables the creation of reusable test scripts and workflows that can be applied across different network environments and devices.

It supports various protocols and devices, allowing for extensive testing coverage.

It integrates well with other Cisco network automation tools and frameworks, making it a versatile choice for network engineers and developers.

References:

Cisco DevNet pyATS documentation

Cisco DevNet Associate Certification Guide

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 Ansible playbook in the exhibit is designed to automate the configuration of HSRP (Hot Standby Router Protocol) on a Cisco Nexus switch listed in the nxos_rtr inventory group. Here’s what the playbook does:

Hosts: The playbook is targeting nxos_rtr hosts.

Task: The task uses the nxos_hsrp module to configure HSRP.

Parameters: Various parameters such as group, VIP, priority, interface, authentication, and version are set for HSRP configuration.

Delegation: The configuration is delegated to the srv-1a inventory host, but it is still targeting the nxos_rtr for the actual HSRP configuration.

Therefore, the playbook is enabling HSRP on the nxos_rtr inventory host.

References:

Cisco DevNet Associate Certification Guide

Ansible Documentation for nxos_hsrp Module

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.

In the given network topology, the communication from Server 1 and Server 2 goes up to device D. Both servers are connected to Device E, which is a Layer 2 switch. Device E is connected to Device D, which serves as the next hop for routing the packets to other parts of the network, including the internet through Device C.

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

References:

Cisco DevNet Documentation - RESTCONF

Cisco DevNet Associate Certification Guide

To enable keepalive for the FastEthernet 2/0 interface using YANG data models and NETCONF in Python, the following steps are required:

Create an Interface Object:

interface = model.Native.Interface.FastEthernet()

This line creates an instance of the FastEthernet interface from the YANG model.

Set the Interface Name:

interface.name = '2/0'

This line sets the name of the interface to 2/0.

Enable Keepalive:

interface.FastEthernet.keepalive_settings.keepalive = True

This line enables the keepalive setting on the FastEthernet interface.

Read the Current Configuration:

interface_data = crud.read(provider, interface)

This line reads the current configuration of the interface from the device.

Update the Configuration:

crud.update(provider, interface)

This line updates the device configuration with the new settings, enabling keepalive on the specified interface.

References:

Cisco YANG Data Models: Cisco YANG Models

YANG Development Kit (YDK): YDK Documentation

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

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

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

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

When using OAuth2 authentication for accessing a protected resource via a REST API, the typical flow involves obtaining an access token which can then be used to authenticate subsequent API requests. The correct process is:

POST Call to /login: Make a POST request to the /login endpoint with the user credentials (username and password) in the request body. This call will authenticate the user and, if successful, return an access token.

Use the Token: Use the retrieved token by including it in the Authorization header (usually as a Bearer token) in the request to access the protected resource, in this case, the /item endpoint.

References:

OAuth 2.0 Authorization Framework - RFC 6749

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

Here is the detailed explanation:

The element initiates a remote procedure call.

The element specifies the operation to be performed.

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

The element contains the configuration data to be applied.

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

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

References:

Cisco DevNet Associate Certification Guide

RFC 6241 - Network Configuration Protocol (NETCONF)

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

The command git reset --soft HEAD^ reverses the last commit but keeps the changes staged in the index file (staging area) and working directory. Here's what the command does:

git reset --soft: Moves the HEAD pointer to the specified commit (in this case, the parent of the current commit, denoted by HEAD^) but leaves the changes from the reset commit in the staging area.

HEAD^: Refers to the parent commit of the current HEAD.

This command is useful when you want to uncommit the last commit but keep the changes for further modification or recommit them.

References:

Git Documentation - git reset

Cisco DevNet Associate Certification Guide

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

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

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

Other Protocols:

DNS: Resolves domain names to IP addresses.

SNMP: Used for monitoring network devices.

NAT: Translates private IP addresses to public IP addresses.

References:

Cisco DevNet Associate Certification Guide

Cisco NTP Overview

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.

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

References:

Cisco DevNet Associate Certification Guide

Cisco IOS XE RESTCONF API Documentation

import requests

data = {

"id": 11,

"summary": "Request summary"

}

response = requests.post('https://todolist.example.com/tasks/ ', json=data)

if response.status_code != 201:

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

for item in response.json():

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

Importing the Requests Library:

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

Creating the Data Payload:

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

Making the POST Request:

The requests.post method is used to send a POST request to the specified URL (https://todolist.example.com/tasks/). The json=data parameter automatically converts the data dictionary to a JSON-formatted string and sets the appropriate headers.

Checking the Response Status Code:

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

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

Processing the JSON Response:

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

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

References:

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

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

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 = 'https://sandboxdnac.cisco.com/dna/intent/api/v1/... '

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

References:

Cisco DNA Center API Documentation

Cisco DevNet Associate Certification Guide

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

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.

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

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

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

References:

Cisco DevNet Documentation - APIs

Cisco DevNet Associate Certification Guide

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

A hybrid cloud deployment model is the best choice for addressing the issue of application crashes due to spikes in user access while allowing for future growth and preserving existing investments. Hybrid cloud integrates on-premises data centers (private cloud) with public cloud services, providing scalability and flexibility. This model allows the company to handle peak loads by offloading traffic to the public cloud while maintaining critical applications and data in the private cloud.

References:

Cisco DevNet Documentation - Hybrid Cloud

Cisco DevNet Associate Certification Guide

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

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

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'}

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 https://devnetlab.local/restconf/api/running/native/interface/GigabitEthernet/2/

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

References:

Cisco RESTCONF API Documentation: RESTCONF API Guide

GIT PUSH

To start a CI/CD pipeline and run automated tests after modifying the code in a cloned repository, the appropriate command is git push. When a developer pushes the changes to the remote repository, it triggers the CI/CD pipeline configured in the repository. Here are the steps:

Clone the repository from GitLab.

Make the necessary code modifications.

Use git commit to commit the changes locally.

Use git push to push the committed changes to the remote repository.

Pushing the changes to the remote repository initiates the CI/CD pipeline, which typically includes steps like building the application, running tests, and deploying the application if tests pass.

References:

Cisco DevNet Associate Certification Guide

GitLab CI/CD Documentation

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

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

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

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

References:

Cisco Webex Features

The 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

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

References:

Atlassian - Comparing code differences

Cisco DevNet Associate Certification Guide

NETCONF (Network Configuration Protocol) is a standard used for network device configuration, and it utilizes YANG (Yet Another Next Generation) as a data modeling language. Cisco IOS XE and Cisco NX-OS support NETCONF and YANG to automate the configuration and management of network devices across a network. YANG defines the data models, while NETCONF provides the protocol to manipulate these models.

References:

Cisco DevNet Documentation - NETCONF and YANG

IETF RFC 6241 - NETCONF Protocol

IETF RFC 6020 - YANG Data Modeling Language

RFC 1918 defines private IP address ranges for use within private networks. The address space 172.16.0.0 to 172.31.255.255 is designated as private and falls under class B.

Class B Address Space: The range 172.16.0.0 to 172.31.255.255 is a private IP address range designated for class B networks.

Subnet Mask: A subnet mask of 255.255.0.0 (/16) is commonly used within this range to create subnets.

References:

RFC 1918 Address Allocation: RFC 1918

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

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

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

References:

IEEE 802 MAC Address Standard

Cisco MAC Address Basics