200-901 Practice Exam Questions with Answers DevNet Associate (DEVASC) Certification

In the given Dockerfile, the WORKDIR /app command sets the working directory for any subsequent commands to /app. This means that any commands following this line will be executed within the /app directory inside the Docker container. The COPY . . command copies the contents of the current directory on the host machine to the /app directory in the container. Finally, the CMD ["node", "source/server.js"] command specifies the command to run when the container starts, which in this case is node source/server.js.

References:

Dockerfile Reference - WORKDIR

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

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

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

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

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

References:

Git and Nonlinear Development: Understanding Git Workflow

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

References:

Test-Driven Development by Example

Cisco DevNet Associate Certification Guide

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

HTTP status code 429 indicates that too many requests have been sent in a given amount of time, which is a sign of rate limiting. Rate limiting is used by APIs to control the amount of incoming requests to prevent abuse or overloading the server. In this case, the Cisco Prime API is limiting the number of requests the network engineer can make in a certain time period, resulting in only a subset of devices being returned and some requests being rejected with a 429 status code.

References:

Cisco DevNet Associate Certification Guide

HTTP Status Code Definitions

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

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

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

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

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

References:

Cisco Model-Driven Programmability

The provided script sends a POST request to the Meraki API endpoint to add a new media server for monitoring. The payload includes the name and address of the media server, indicating that the action being automated is the addition of a media server to the monitoring list.

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 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

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

OR

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

References:

Ansible Documentation - Variable precedence

Cisco DevNet Associate Certification Guide

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

Example:

GET /v1/rooms?sortBy=lastactivity

References:

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

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

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

References:

Cisco Router Basics

Broadcast Domains and Routers

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

Grpc == http/2 , netconfig == ssh , restconfig == https

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

Function of a Firewall:

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

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

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

Comparison with Other Devices:

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

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

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

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

References:

Cisco Firewalls Overview: Cisco Firewall Products

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

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

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

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

References:

Cisco Intersight API Documentation

Cisco UCS Manager API Documentation

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)

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.

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

The YANG 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

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.

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.

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

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

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

1 – B, 2 – E, 3 - F

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

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

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

In REST architecture, the stateless constraint indicates that no client context should be stored on the server between requests. Each request from the client to the server must contain all the information needed to understand and process the request.

Stateless: Ensures that each request is independent and contains all necessary information.

Uniform interface: Defines a standard way of interacting with resources.

Cacheable: Responses must define whether they are cacheable to improve performance.

Client-server: Separates the client and server roles.

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.

Top of Form

Bottom of Form

Generating log bundles is a resource-intensive task that can cause high CPU utilization on the Cisco DNA Center. When the CPU spikes, it can affect the performance of other critical tasks, such as forwarding voice IP packets, leading to delays and poor voice quality. This is especially noticeable during business hours when network utilization is high, and voice traffic is sensitive to latency and jitter. More details can be found in Cisco DNA Center documentation on Managing Logs and System Performance.

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

12.00

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

YANG model-driven programmability allows for the configuration of devices using data models. In NX-OS, this includes both native and OpenConfig-based models.

YANG Models: These are used to model configuration and state data for network devices. Native models are specific to the vendor, while OpenConfig models are vendor-neutral.

Configuration Management: YANG models facilitate consistent and programmable configuration of network devices, which can be done through APIs like NETCONF or RESTCONF.

The HTTP status code 200 indicates successful execution of a request.

Status Code 200:

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

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

HEAD: The headers are in the message body.

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

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

Comparison with Other Codes:

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

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

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

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

References:

HTTP Status Codes: MDN Web Docs

git add .

git commit -m “this is my edit”

git push

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

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

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

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)

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

Cisco Unified Communications Manager (CUCM) provides APIs to access various data related to unified communications, including voicemail ports. These APIs allow developers to retrieve information about voicemail port configurations, usage statistics, and status. Cisco provides extensive documentation on how to use these APIs for integration and data retrieval purposes, which can be found in the Cisco Unified Communications Manager Developer Guide.

The CNAME (Canonical Name) record is used in DNS to create an alias that points to another domain name. This domain name then resolves to an IP address. For instance, if you have a CNAME record for www.example.com pointing to example.com, accessing www.example.com will direct you to example.com, which will ultimately resolve to the IP address of example.com. This is particularly useful for pointing multiple domain names to the same IP address, allowing easier maintenance and updates. References for this can be found in Cisco's DNS documentation.

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

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

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

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

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

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

The "time exceeded in-transit" ICMP message is generated when a packet's Time-To-Live (TTL) field reaches zero before reaching its destination. This usually occurs when the packet has traversed too many routers (hops), indicating that the destination is too far away or there is a routing loop causing excessive hops.

TTL Field: Every IP packet has a TTL field which decrements by 1 every time it passes through a router. When TTL reaches zero, the packet is discarded and an ICMP "time exceeded" message is sent back to the sender.

Network Latency: High latency or excessive hops can cause packets to expire in transit, leading to this ICMP message.

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.

1 – C, 2 – D, 3 – B, 4 - A

Functions in programming are a fundamental concept that provide several key benefits:

Modularity: By breaking down a program into smaller, manageable functions, it becomes easier to understand, debug, and maintain.

Reusability: Functions allow code to be reused across the program, reducing redundancy.

Abstraction: Functions can abstract complex operations into a simple function call, making the code easier to read and understand.

Testing: Functions can be tested individually, which simplifies the process of testing the overall program.

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

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)

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

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

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

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.

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

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

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

SNMP: Used for network management and monitoring.

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

References:

Cisco DNS Documentation

? 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.

Check below the answer exact.

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

A 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

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

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

References:

Git Branching Basics

The --no-ff option in the git merge command ensures that a merge commit is always created, even when a fast-forward merge is possible. This is useful for keeping a clear history of feature branches being merged into the main branch.

Fast Forward Merge: By default, Git performs a fast-forward merge if there are no diverging changes. This can result in a linear commit history without a separate merge commit.

Using --no-ff: The --no-ff option forces Git to create a merge commit, preserving the context that a feature branch was merged into the main branch, which is crucial for record-keeping and audit trails.

References:

Git Merge Documentation: Git Merge

Network Address Translation (NAT) on the firewall is responsible for translating the public IP address to the private IP addresses of internal servers. If traffic is being forwarded to the wrong server, it indicates a misconfiguration in the NAT rules.

NAT Configuration: NAT rules need to be correctly configured to forward traffic to the appropriate internal server based on the destination IP and port.

Misconfiguration: If NAT rules are incorrect, traffic may be directed to the wrong internal IP address, as seen in the exhibit where traffic is sent to server 1 instead of server 2.

Option D is correct as the issue is caused by NAT misconfiguration on the firewall.

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.

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

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

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

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

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

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

GigabitEthernet1

1

1

408164820

728061

To provide an encrypted connection when using API keys to communicate with a REST API, the connection must use HTTPS. The curl command with the -X GET option and an HTTPS URL ensures that the communication is encrypted, protecting the API key and data in transit.

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

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

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

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

References:

Cisco DevNet Sandbox: DevNet Sandbox

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

References:

Cisco DevNet Associate Certification Guide

Cisco Networking Essentials, Chapter on Routing and Switching Basics

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

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

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

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

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

References:

Rate Limiting and API Performance: Understanding Rate Limiting

An HTTP 403 Forbidden error indicates that the server understands the request but refuses to authorize it. This often occurs when the user making the request does not have the necessary permissions to access the resource.

To resolve this issue:

Correct User Access Rights: Ensure that the developer has the appropriate permissions to access the API endpoint. This typically involves verifying the user's roles and permissions within the system or application being accessed.

References:

HTTP 403 Forbidden Error - MDN Web Docs

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

git clone git@github.com:myproject aci

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

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

References:

Git Clone Documentation

GitHub SSH Setup

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

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

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

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

Comprehensive Detailed Step by Step Explanation with References

Synchronous:

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

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

Asynchronous:

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

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

REST (Representational State Transfer):

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

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

RPC (Remote Procedure Call):

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

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

References:

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

Official Cisco documentation on RESTful and RPC APIs

General programming resources on synchronous vs. asynchronous API calls

Therefore, the correct mapping is:

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

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

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

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

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

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

References:

Cisco DevNet Associate Certification Guide

Cisco Meraki API Documentation

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

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

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

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

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

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

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

References:

Infrastructure as Code Overview: IaC Introduction

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

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

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

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

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

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

References:

Continuous Integration Fundamentals: CI/CD Overview

To build a Docker image using the current folder and a specified Dockerfile, and then tag the image with a specific name for the local repository, the following command is used:

docker build: This command builds a Docker image from a Dockerfile.

-t cust321453857-rep: The -t option tags the resulting image with the specified name (cust321453857-rep).

-f Dockerfile: The -f option specifies the Dockerfile to use for building the image.

Command:

docker build -t cust321453857-rep -f Dockerfile .

References:

Docker Build Command: Docker Build

In the provided Python code, the API_PASSWORD is retrieved from the environment variable API_PASSWORD. To set this environment variable in a Bash shell, the correct command to use is export. This command sets the environment variable for the current shell session and any child processes.

Bash Command: export API_PASSWORD=Cisco123!

This command ensures that the environment variable API_PASSWORD is set to "Cisco123!" and can be accessed by the Python script.

References:

Bash export Command

Cisco DevNet Associate Certification Guide

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

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).

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

References:

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

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

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).

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.

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

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

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.

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

YANG Model Analysis:

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

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

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

Key Elements in JSON:

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

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

Options Analysis:

Option A:

json

Copy code

"ietf-interfaces:interface": {

"name": "Loopback100",

"enabled": true,

"ietf-ip:ipv4": {

"address": [

{

"ip": "10.255.254.1",

"netmask": "255.255.255.0"

}

]

}

}

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

Option B:

"ietf-interfaces": {

"interface": {

"name": "Loopback100",

"enabled": true,

"ietf-ip": {

"ipv4": {

"address": [

{

"ip": "10.255.254.1",

"netmask": "255.255.255.0"

}

]

}

}

}

}

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

Option C:

"interface": {

"name": "Loopback100",

"enabled": true,

"ipv4": {

"address": [

{

"ip": "10.255.254.1",

"netmask": "255.255.255.0"

}

]

}

}

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

Option D:

"ietf-interfaces:interface": {

"name": "Loopback100",

"enabled": true,

"ietf-ip:ipv4:address": [

{

"ip": "10.255.254.1",

"netmask": "255.255.255.0"

}

]

}

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

Correct Explanation:

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

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

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

References:

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

YANG Data Models in NETCONF: RFC 6020

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

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

References:

YAML vs. JSON

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

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

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

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

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

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 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 HTTP call to create a room named "cisco" through the Webex API is returning a 400 Bad Request error because the body parameter is incorrect. The correct body parameter to create a room is "name" instead of "team".

A. Replace the team body parameter with the name body parameter - Correct. The correct parameter for creating a room is "name". B. Replace cisco with a valid name for a team - Incorrect. The issue is with the parameter name, not the value. C. Change the token in the header with the authorization token - Incorrect. The token appears to be correct since it is a 400 error and not a 401 Unauthorized error. D. Change the HTTP method of the call to PUT - Incorrect. The correct HTTP method for creating a room is POST.

References:

Cisco Webex API Documentation - Create a Room

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.

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

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

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

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

References:

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

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

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

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

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

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

Cisco 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).

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 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

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

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 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.

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;'"

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

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

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

References:

Cisco Network Fundamentals

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).

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).

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 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 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.

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

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.

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).

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

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

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

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

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

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

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

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).