200-901 Cisco DevNet Associate (DEVASC) Free Practice Exam Questions (2025 Updated)

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

The docker run command is used to create and start a new container from an image. The -p option maps a port on the host to a port in the container.

Port Mapping: The syntax -p [host_ip:host_port:container_port/protocol] is used to map ports.

Exposing Port 8443: The correct mapping to expose the API on port 8443 and allow external connections is 0.0.0.0:443:8443/tcp, which maps port 443 on the host to port 8443 in the container.

Option B correctly maps the ports and allows external connections.

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

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

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

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

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

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

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

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

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

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

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 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.

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).

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.

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

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

References:

Test-Driven Development (TDD) Patterns

Growing Object-Oriented Software, Guided by Tests

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

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 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

A developer is creating a script to interact with a REST API service that requires basic authentication. The correct combination of payload and headers using Basic Authentication with the provided Base64 encoded credentials is:

A. This option does not use headers correctly. B. Option B - Correct. This option correctly places the 'Authorization' header in the headers dictionary with 'Basic' authentication. C. This option uses 'Bearer' instead of 'Basic' for the 'Authorization' header. D. This option uses 'Bearer' instead of 'Basic' for the 'Authorization' header.

References:

HTTP Authentication

Base64 Encoding