200-901 Infrastructure and Automation — Timed 10 Questions

Question 1

Which protocol is commonly used to retrieve real-time telemetry data from network devices in a streaming fashion?

Accepted Answer

gRPC. gRPC is correct because it is designed for high-performance, real-time streaming of telemetry data using HTTP/2 and Protocol Buffers. Network devices like Cisco IOS XR and NX-OS use gRPC to push telemetry data to collectors in a continuous stream, eliminating the need for polling and reducing latency.

Answer

SNMP polling

Answer

NETCONF

Answer

HTTP

Question 2

Which THREE of the following are best practices for writing Ansible playbooks for network automation? (Select exactly 3.)

Accepted Answer

Include a validation task after configuration changes. Option B is correct because including a validation task after configuration changes confirms the device reached the intended state and catches failed or partial deployments before moving on. Option C is correct because using variables for device-specific parameters (for example, hostnames, IPs, or interface names) keeps playbooks reusable across many devices instead of duplicating logic. Option E is correct because 'changed_when' lets you accurately report whether a task actually modified device state, which is essential for idempotency and reliable reporting in network modules that may not natively detect change. Option A is not a best practice because ignoring errors hides failures and can leave devices in an inconsistent state. Option D is not a best practice because hardcoding device IPs makes playbooks brittle and non-reusable; those values should come from inventory or variables.

Answer

Run all tasks without checking for errors

Answer

Hardcode device IPs in the playbook

Question 3

Refer to the exhibit. An automation script expects the interface IP address to be configured via DHCP. Based on the output, what is the current configuration source for the IP address?

Accepted Answer

Manual configuration (NVRAM). The output shows 'IP address is 192.168.1.1, subnet mask is 255.255.255.0' with no DHCP or BOOTP flags, and the configuration is stored in NVRAM (startup-config). This indicates the IP was manually configured (typed by an administrator) and saved, not obtained via DHCP. Option C is correct because the source is manual configuration from NVRAM.

Answer

DHCP

Answer

BOOTP

Answer

PPP negotiation

Question 4

Refer to the exhibit. A Python script uses the YANG model to configure the interface. After applying this JSON payload via a PATCH request, what is the expected operational state of the interface?

Accepted Answer

Administratively down. The PATCH request applies the provided JSON payload, which sets the interface's 'enabled' leaf to 'false' (or equivalent YANG leaf for administrative state). In YANG models for interfaces (e.g., RFC 8343 or Cisco native models), setting 'enabled' to false places the interface in an administratively down state. The PATCH operation is valid for modifying interface configuration, and the payload explicitly changes the administrative state to down, overriding any previous configuration.

Answer

Error because PATCH is not allowed on interfaces

Answer

No change, remains as previously configured

Answer

Administratively up and protocol up

Question 5

Refer to the exhibit. An Ansible playbook targeting a Cisco IOS device fails with this error. What is the most likely cause?

Accepted Answer

Wrong SSH username or password. The error message in Ansible typically indicates an authentication failure when connecting to the Cisco IOS device via SSH. Option D is correct because the playbook likely specifies incorrect SSH credentials (username or password), preventing Ansible from authenticating with the device. Ansible uses the `ansible_user` and `ansible_ssh_pass` or `ansible_password` variables for SSH authentication, and a mismatch will cause a 'Authentication failed' or 'Permission denied' error.

Answer

The device is unreachable

Answer

The playbook syntax is incorrect

Answer

The device is not running IOS

Question 6

You are a network automation engineer at a large enterprise. The network consists of 200 Cisco Catalyst switches distributed across five data centers. Each switch runs IOS-XE and supports NETCONF. Your team uses a centralized Ansible control node to manage configurations. Recently, the security team mandated that all management access must use SSH keys instead of passwords. You updated the Ansible inventory to use SSH keys and tested on a few switches successfully. However, when you run the playbook against all switches, about 30 switches fail with the error: 'Authentication failed.' You verify that the SSH public key is correctly deployed on those switches via the console. What is the most likely cause of the failure?

Accepted Answer

The private key file on the Ansible control node has permissions 644, which SSH rejects. SSH strictly requires private key files to have permissions no more permissive than 600 (owner read/write) or 640 (owner read/write, group read) on Unix-like systems. A permission of 644 allows group and others to read the key, which SSH interprets as insecure and refuses to use, causing 'Authentication failed' even though the public key is correctly deployed on the switches.

Answer

The public key on the switches is not in the correct format

Answer

The Ansible become method is misconfigured

Answer

The switches are not reachable over the network

Question 7

You are automating the deployment of a new software image on a fleet of Cisco Nexus switches using Ansible. The switches are in a production environment and must have minimal downtime. You have a maintenance window of 30 minutes per switch. Your playbook performs the following steps: 1) Copy the image to the switch via SCP, 2) Set the boot variable to the new image, 3) Save the configuration, 4) Reload the switch. During a dry run on a test switch, you notice that the reload step takes 8 minutes, but the copy step takes 15 minutes due to slow link speed. For the production rollout, you need to reduce the overall time per switch. Which approach should you take?

Accepted Answer

Use a local file server with HTTP for image transfer to improve speed. The bottleneck is the SCP copy time (15 minutes), which exceeds the 30-minute maintenance window when combined with the reload (8 minutes). Using HTTP for image transfer leverages a more efficient protocol with better throughput and lower overhead than SCP, which uses SSH encryption and can be slower on low-bandwidth links. This directly reduces the copy time, bringing the total per-switch time under the maintenance window limit.

Answer

Skip the save configuration step to save time

Answer

Use a compressed image to reduce copy time

Answer

Reload all switches simultaneously in the same maintenance window

Question 8

Refer to the exhibit. A network engineer applies this JSON-based QoS policy to a Cisco device using NETCONF/YANG. Which statement best describes the expected behavior for traffic from 10.0.0.0/24 with DSCP EF?

Accepted Answer

Traffic from 10.0.0.0/24 with DSCP EF is re-marked to AF41 and limited to 100 Mbps; excess is dropped.. The JSON-based QoS policy uses a class map matching traffic from source 10.0.0.0/24 with DSCP EF, then applies a police action that re-marks exceeding traffic to AF41 and drops it when the rate exceeds 100 Mbps. This is a standard two-rate policer behavior in Cisco IOS QoS, where conforming traffic is transmitted unchanged and exceeding traffic is re-marked and dropped.

Answer

Traffic with DSCP EF from any source is re-marked to AF41 and dropped if exceeding 100 Mbps.

Answer

The policy is invalid because DSCP values cannot be changed in a QoS policy.

Answer

Traffic from 10.0.0.0/24 is re-marked to DSCP EF, then policed at 100 Mbps.

Question 9

An automation engineer wants to programmatically retrieve the interface configuration of a Cisco Nexus switch using NX-API. Which API call method is most appropriate?

Accepted Answer

GET. The NX-API on Cisco Nexus switches uses HTTP methods that map to CRUD operations. To retrieve (read) interface configuration without modifying any state, the GET method is the correct and most appropriate choice, as it corresponds to the 'show' commands in the CLI. POST, PUT, and DELETE are intended for creating, updating, or deleting resources, not for read-only queries.

Answer

POST

Answer

DELETE

Answer

PUT

Question 10

During a CI/CD pipeline for network changes, a Jenkins job runs an Ansible playbook that applies configuration to a device. The playbook fails with a timeout error. What is the most likely cause?

Accepted Answer

The device is under heavy CPU load causing slow responses. A timeout error in an Ansible playbook during a CI/CD pipeline typically indicates that the network device is responding too slowly to complete the SSH or API session within the configured timeout period. Heavy CPU load on the device can cause delayed responses to Ansible's control node, triggering the timeout before the playbook finishes applying the configuration. This is distinct from connectivity failures or authentication issues, which produce different error messages.

Answer

The playbook syntax is invalid

Answer

Incorrect credentials

Answer

Device is unreachable