200-901 Practice Test 27 — 15 Questions

Question 1

An engineer is troubleshooting a connectivity issue between two devices on different VLANs. The switch connecting the devices is configured with 802.1Q trunking. At which OSI layer do VLANs operate?

Accepted Answer

Layer 2. VLANs operate at Layer 2 (Data Link) because they segment broadcast domains based on MAC addresses and logical grouping, but they do not involve IP routing (Layer 3).

Answer

Layer 4

Answer

Layer 1

Answer

Layer 3

Question 2

An Ansible playbook fails with the error: "mapping values are not allowed here". The relevant YAML snippet is:
---
- name: Configure interface
  ios_config:
    lines:
      - ip address 10.0.0.1 255.255.255.0
    parents: interface GigabitEthernet0/1
  What is the most likely cause of this error?

Accepted Answer

The indentation of `parents:` is incorrect relative to `lines:`. The error 'mapping values are not allowed here' occurs in YAML when a key-value pair is incorrectly indented relative to its parent. In this snippet, `parents:` is indented at the same level as `lines:`, but it should be a sibling of `lines:` under the same dictionary key. The correct indentation requires `parents:` to be aligned with `lines:` (both at the same indentation level under `ios_config:`), but the error suggests that `parents:` is placed where YAML expects a scalar value, breaking the mapping structure.

Answer

The `ios_config` module requires a provider statement

Answer

The `lines:` item should be a list of strings

Answer

The `parents:` value must be enclosed in quotes

Question 3

Which DNS record type is used to verify domain ownership for email security (SPF)?

Accepted Answer

TXT record. SPF (Sender Policy Framework) is stored in a TXT record.

Answer

A record

Answer

CNAME record

Answer

MX record

Question 4

In a wireless network using 802.11ac, which frequency band does the standard primarily operate in to achieve higher throughput?

Accepted Answer

5 GHz. 802.11ac (Wi-Fi 5) operates exclusively in the 5 GHz band, allowing wider channels and higher throughput.

Answer

2.4 GHz

Answer

6 GHz

Answer

Both 2.4 GHz and 5 GHz

Question 5

A developer is writing a Python script to interact with a REST API. The API requires a JSON payload to create a new resource. Which HTTP method should be used?

Accepted Answer

POST. POST is used to create a new resource on the server.

Answer

PATCH

Answer

PUT

Answer

GET

Question 6

A developer is building a real-time video streaming application that must minimize delay, even if some packets are lost. Which transport protocol is most appropriate, and why?

Accepted Answer

UDP, because it has lower overhead and no retransmission delay.. UDP is suitable for real-time streaming because it is connectionless and does not retransmit lost packets, reducing latency. TCP's retransmission and ordering would cause delays.

Answer

TCP, because it provides flow control to avoid congestion.

Answer

UDP, because it guarantees packet delivery.

Answer

TCP, because it ensures all packets arrive in order.

Question 7

In the context of SDN, which API is used between the SDN controller and the network devices to configure forwarding behavior?

Accepted Answer

Southbound API. Southbound APIs like OpenFlow, NETCONF, or gRPC communicate from controller to devices.

Answer

Northbound API

Answer

Eastbound API

Answer

REST API

Question 8

A network engineer is designing a subnetting scheme for a company that requires 5 subnets from the 192.168.1.0/24 network. What subnet mask should be used, and how many usable hosts per subnet will be available?

Accepted Answer

255.255.255.224 with 30 usable hosts per subnet. To create 5 subnets, at least 3 bits are needed (2^3=8 subnets). /27 (255.255.255.224) gives 8 subnets with 30 usable hosts each (2^5-2=30).

Answer

255.255.255.192 with 62 usable hosts per subnet

Answer

255.255.255.240 with 14 usable hosts per subnet

Answer

255.255.255.248 with 6 usable hosts per subnet

Question 9

Which TWO of the following are characteristics of a declarative automation model? (Select exactly 2.)

Accepted Answer

You specify the desired end state. In a declarative automation model, you specify the desired end state of the system, not the steps to achieve it. This is a core characteristic because the automation tool (e.g., Ansible, Terraform, Puppet) interprets the desired state and determines the necessary actions to reach it, making option B correct.

Answer

It requires procedural scripts

Answer

Idempotency is not a concern

Answer

You specify the exact steps to achieve the state

Question 10

Which TWO statements correctly describe differences between model-driven telemetry and traditional SNMP polling?

Accepted Answer

Model-driven telemetry reduces device CPU usage compared to frequent SNMP polling. Model-driven telemetry uses a push model that sends data only when there is a change or at a configured interval, which significantly reduces the device CPU overhead compared to frequent SNMP polling, where the device must process and respond to each individual GET request from the NMS. This efficiency gain is a primary advantage of telemetry over traditional polling.

Answer

SNMP supports push-based notifications using informs

Answer

Model-driven telemetry can only be used with NETCONF

Answer

SNMP uses YANG models for data definition

Question 11

When using NETCONF to edit the configuration of a Cisco IOS XE device, an engineer receives an <rpc-error> with error-tag 'in-use' and error-app-tag 'data-exists'. What does this error indicate?

Accepted Answer

The configuration being added already exists on the device.. The error-tag 'in-use' combined with the error-app-tag 'data-exists' in NETCONF indicates that the configuration operation (e.g., <edit-config> with operation 'create') attempted to add a configuration element that already exists in the running datastore. NETCONF uses these standardized error tags per RFC 6241 to signal that the requested operation cannot be completed because the target data node is already present, preventing duplicate configuration entries.

Answer

The NETCONF session was closed due to a timeout.

Answer

The RPC message was malformed.

Answer

The device does not have the required user permissions.

Question 12

A developer is building a chat application that requires low-latency communication, and occasional packet loss is acceptable. Which transport protocol should the developer choose?

Accepted Answer

UDP. UDP is the correct choice because it provides low-latency, connectionless communication without retransmission or congestion control, making it ideal for real-time chat applications where occasional packet loss is acceptable. Unlike TCP, UDP does not require a handshake or acknowledgment, minimizing delay and overhead.

Answer

RTP

Answer

QUIC

Answer

TCP

Question 13

A network administrator is configuring DNS for a corporate domain. An MX record is required to specify the mail server responsible for handling email. Which of the following is a correct example of an MX record?

Accepted Answer

example.com.  MX  10 mail.example.com.. An MX record specifies the mail server responsible for handling email for a domain, using the format: domain. MX priority mailserver. The priority value (10) indicates preference, with lower values being higher priority. This record directs email delivery to mail.example.com for the example.com domain.

Answer

mail.example.com.  A  192.0.2.1

Answer

example.com.  CNAME  mail.example.com.

Answer

example.com.  TXT  "v=spf1 include:_spf.google.com ~all"

Question 14

A developer wants to run a Docker container in detached mode, mapping host port 8080 to container port 80, and mounting a host directory for persistent data. Which command accomplishes this?

Accepted Answer

docker run -d -p 8080:80 -v /host/data:/container/data myapp. The -d flag runs detached, -p maps ports, and -v mounts a volume from host to container.

Answer

docker run -it -p 8080:80 -v /host/data:/container/data myapp

Answer

docker start -d -p 8080:80 -v /host/data:/container/data myapp

Answer

docker compose up -d -p 8080:80 -v /host/data:/container/data myapp

Question 15

A team is deploying a new microservice on Cisco Container Platform. The microservice needs to access a database hosted on a separate VM. The security policy requires that only the microservice can communicate with the database, and all traffic must be encrypted. The team is using Kubernetes network policies and mutual TLS. During testing, the microservice cannot reach the database. The database team reports that the database is reachable from other services. What is the most likely cause?

Accepted Answer

A Kubernetes NetworkPolicy is blocking egress from the microservice pod to the database IP. The most likely cause is that a Kubernetes NetworkPolicy is blocking egress from the microservice pod to the database IP. Since the database is reachable from other services, the issue is specific to the microservice pod's network access. A NetworkPolicy that does not explicitly allow egress traffic to the database IP will default to denying that traffic, preventing the microservice from reaching the database even though the database itself is operational.

Answer

The database server is not listening on the expected port

Answer

The mutual TLS certificates are expired or not trusted

Answer

The Istio sidecar proxy is misconfigured and rejecting traffic due to a missing ServiceEntry