200-901 Practice Test 29 — 15 Questions

Question 1

A network engineer is designing a subnet that needs to support 30 usable hosts. Which subnet mask should be used?

Accepted Answer

255.255.255.224 (/27). (255.255.255.224, /27) provides 5 host bits, yielding 2^5 = 32 total addresses per subnet. Subtracting the network and broadcast addresses leaves exactly 30 usable hosts, meeting the requirement precisely.

Answer

255.255.255.240 (/28)

Answer

255.255.255.0 (/24)

Answer

255.255.255.192 (/26)

Question 2

A network engineer is subnetting the network 192.168.1.0/24 into subnets that each support at least 50 hosts. What subnet mask should be used?

Accepted Answer

255.255.255.192 (/26). To support at least 50 hosts, you need 6 host bits (2^6 - 2 = 62 usable addresses). A /26 subnet mask (255.255.255.192) provides exactly 6 host bits, meeting the requirement. The original /24 network is borrowed with 2 subnet bits, yielding 4 subnets of 64 addresses each.

Answer

255.255.255.224 (/27)

Answer

255.255.255.240 (/28)

Answer

255.255.255.128 (/25)

Question 3

Refer to the exhibit. A PC is connected to interface GigabitEthernet0/1 on a Cisco switch. The PC is in VLAN 10. What is the purpose of the 'spanning-tree portfast' command on this interface?

Accepted Answer

It allows the interface to transition directly to forwarding state.. The 'spanning-tree portfast' command on a switch interface connected to an end host (like a PC) allows that port to bypass the listening and learning states and transition directly to the forwarding state. This is correct because PortFast is designed for access ports that connect to end devices, which do not participate in spanning tree, thereby eliminating the 30-second delay (15 seconds for listening, 15 seconds for learning) and providing immediate connectivity.

Answer

It disables STP on the interface.

Answer

It prevents the interface from entering blocking state.

Answer

It enables BPDU guard on the interface.

Answer

It enables Rapid Spanning Tree on the interface.

Question 4

Which TWO are components of a REST API request? (Choose two.)

Accepted Answer

URI. A REST API request is defined by the combination of a URI (Uniform Resource Identifier) and an HTTP method. The URI identifies the specific resource (e.g., /api/users/123) on the server, while the HTTP method (GET, POST, PUT, DELETE, etc.) specifies the desired action to be performed on that resource. Together, they form the fundamental components that the client sends to the server to initiate a request.

Answer

Status code

Answer

Payload

Answer

Query string

Question 5

Which THREE of the following are key principles of Infrastructure as Code (IaC) as applied to network automation?

Accepted Answer

Configuration should be idempotent.. Idempotency ensures that applying the same configuration multiple times results in the same final state, preventing unintended changes. In network automation, tools like Ansible or Terraform use idempotent modules (e.g., `ios_config`) to verify the current device state before applying changes, avoiding configuration drift or repeated command failures.

Answer

Manual configuration is preferred for critical devices.

Answer

Temporary scripts should be used for one-time changes.

Question 6

Which DNS record type is used to map a domain name to an IPv6 address?

Accepted Answer

AAAA. The AAAA (quad-A) record is the DNS resource record type defined in RFC 3596 to map a fully qualified domain name to a 128-bit IPv6 address. Unlike the A record, which stores a 32-bit IPv4 address, the AAAA record holds the longer IPv6 address, enabling clients to resolve hostnames to IPv6 destinations.

Answer

A

Answer

CNAME

Answer

MX

Question 7

Which of the following is a private IPv4 address range as defined by RFC 1918?

Accepted Answer

192.168.0.0/16. RFC 1918 defines private IPv4 address ranges that are not routable on the public Internet. The 192.168.0.0/16 range (192.168.0.0 – 192.168.255.255) is explicitly listed in RFC 1918 as a Class C private block, making option A correct.

Answer

172.32.0.0/12

Answer

172.15.0.0/12

Answer

11.0.0.0/8

Question 8

Which HTTP method is idempotent and used to update a resource by sending the full representation?

Accepted Answer

PUT. PUT is idempotent because making the same request multiple times results in the same server state. It requires the client to send a full representation of the resource, replacing any existing resource at that URI. This aligns with RFC 7231, which defines PUT as a method that creates or replaces the target resource with the enclosed representation.

Answer

DELETE

Answer

POST

Answer

GET

Question 9

A developer is trying to access an internal corporate web API at http://api.internal.company.com from their workstation, which has the IP configuration: IP address 192.168.1.100, subnet mask 255.255.255.0, default gateway 192.168.1.1, and DNS server 192.168.1.2. The developer can ping the DNS server (192.168.1.2) successfully, but when they try to curl the API endpoint, the command times out. The developer also confirms that the API server is up and reachable from other devices on the same subnet. Which action should the developer take to resolve this issue?

Accepted Answer

Check the default gateway configuration. Ensure it is set to 192.168.1.1 and that the gateway can route traffic to the API's subnet.. The developer can ping the DNS server (192.168.1.2) successfully, which confirms that local network connectivity and DNS resolution are working. However, the curl command to the API endpoint times out, even though the API server is reachable from other devices on the same subnet. This indicates that the workstation can reach local resources but cannot route traffic to the API's subnet, pointing to a default gateway misconfiguration. Option D is correct because the default gateway (192.168.1.1) must be correctly configured and capable of forwarding traffic to the destination subnet; if it is missing or misconfigured, outbound traffic to non-local networks will fail.

Answer

Disable the local firewall on the workstation to allow all outbound traffic.

Answer

Renew the DHCP lease to obtain a new IP address.

Answer

Restart the network interface card (NIC) to reset the connection.

Question 10

An engineer is configuring IOS XE for RESTCONF. Which YANG module must be enabled to use RESTCONF?

Accepted Answer

restconf. RESTCONF is a standardized protocol (RFC 8040) that uses HTTP methods to access data defined in YANG modules. To enable RESTCONF on IOS XE, the 'restconf' module must be explicitly enabled in the configuration, typically via the 'restconf' global command. Without this module, the RESTCONF server will not start, and HTTP requests to the RESTCONF API will fail.

Answer

Cisco-IOS-XE-native

Answer

netconf-yang

Answer

nxapi

Question 11

Which THREE of the following are common steps in a CI/CD pipeline for a Python application that manages Cisco devices?

Accepted Answer

Build a Docker container. Containerizing the Python application with Docker ensures consistent runtime environments across development, testing, and production. This is especially important for managing Cisco devices, as dependencies like Netmiko or NAPALM must be reliably available. Docker also simplifies integration with orchestration tools like Kubernetes for scaling network automation tasks.

Answer

Manually review code before merge

Answer

Deploy to production on every commit

Question 12

During a code review, a developer notices that a function has multiple nested if-else statements. Which refactoring technique would improve maintainability?

Accepted Answer

Replace conditional with polymorphism. Replacing complex conditionals with polymorphism aligns with the Open/Closed Principle, allowing each subclass to handle its own behavior without modifying existing code. This refactoring technique directly addresses the maintainability issue of deeply nested if-else statements by delegating decision logic to polymorphic method dispatch, which is a core object-oriented design pattern tested in the 200-901 exam.

Answer

Introduce parameter object

Answer

Decompose conditional

Answer

Extract method

Question 13

A developer wants to receive real-time notifications when a new message is posted in a Webex room. Which Webex API resource should they use?

Accepted Answer

Webhooks. Webhooks provide real-time HTTP callbacks triggered by events in Webex, such as a new message being posted. By registering a webhook on the 'messages' resource with the 'created' event, the developer's server receives a POST request immediately when a message is sent, eliminating the need for polling.

Answer

Memberships API

Answer

Rooms API

Answer

Messages API polling

Question 14

A network engineer is planning to use model-driven programmability with YANG models. Which three statements about YANG models are correct?

Accepted Answer

pyang is a tool that can be used to explore YANG models.. A is correct because pyang is a command-line tool that validates and converts YANG models into various formats (e.g., tree, UML, YIN), enabling engineers to explore the structure and semantics of YANG modules. It is widely used in network automation workflows to inspect model hierarchies and dependencies before implementing NETCONF or RESTCONF configurations.

Answer

OpenConfig models are vendor-specific.

Answer

YANG models are only used with NETCONF, not RESTCONF.

Question 15

Which design principle suggests that a module should be responsible for a single part of the functionality?

Accepted Answer

Separation of Concerns. Separation of Concerns (SoC) is the design principle that dictates each module or component should focus on a single, well-defined part of the functionality. In software development, this reduces coupling and increases cohesion, making code easier to maintain, test, and refactor. For example, in a Python Flask web application, separating route handling, business logic, and database access into distinct modules follows SoC.

Answer

YAGNI (You Aren't Gonna Need It)

Answer

DRY (Don't Repeat Yourself)

Answer

KISS (Keep It Simple, Stupid)