200-901 Practice Test 34 — 15 Questions

Question 1

A developer is designing a microservices architecture for a network monitoring application. Which of the following is a key advantage of microservices over a monolithic architecture?

Accepted Answer

Independent deployability and scalability of services. Microservices architecture enables each service to be deployed, updated, and scaled independently without affecting other services. This is a key advantage over monolithic architectures, where any change requires rebuilding and redeploying the entire application. For a network monitoring application, independent scalability allows resource-intensive services (e.g., packet capture) to scale separately from lightweight services (e.g., alerting).

Answer

Lower latency due to in-process communication

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Easier to maintain as a single codebase

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Simpler inter-service communication

Question 2

A Python script uses the Cisco Webex API to list all rooms. The response includes pagination via the 'Link' header with 'rel="next"'. What is the correct way to retrieve the next page of rooms?

Accepted Answer

Parse the 'Link' header for the URL with 'rel="next"' and send a GET request to that URL.. The Webex API uses HTTP Link headers for pagination, as specified in RFC 5988. The 'Link' header contains a URL with 'rel="next"' that points directly to the next page of results. To retrieve the next page, you must parse this header, extract the URL, and send a GET request to that URL. This is the standard approach for cursor-based or token-based pagination, which is common in RESTful APIs that avoid offset-based pagination for consistency.

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Increment a page counter and append '?page=2' to the original URL.

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Use the total count returned in the response to calculate the offset.

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Send a POST request to the same endpoint with the 'cursor' parameter.

Question 3

A developer is using the Meraki Dashboard API and notices that some requests return a 429 status code. What is the most likely cause?

Accepted Answer

The rate limit of 5 requests per second has been exceeded.. HTTP 429 means 'Too Many Requests.' The Meraki Dashboard API enforces a rate limit of 5 requests per second per organization, and exceeding it returns a 429 with a Retry-After header. The developer should implement exponential backoff and respect the Retry-After value.

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The organization ID is incorrect.

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The request payload is too large.

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The API key is invalid.

Question 4

Which TWO of the following are benefits of using NETCONF over SNMP for network automation? (Select exactly 2.)

Accepted Answer

Structured data models (YANG). Option A is correct because NETCONF uses YANG data models to define configuration and state data in a structured, hierarchical, vendor-neutral way, which is far more suitable for programmatic automation than SNMP's flat MIB/OID model. Option D is correct because NETCONF supports transactional configuration changes via candidate datastores, commit, confirmed-commit, and rollback-on-error, so a set of edits either fully applies or is rolled back, unlike SNMP SET operations which are not transactionally grouped. Option B is not a defining benefit of NETCONF over SNMP; NETCONF over SSH can actually be more resource-intensive than lightweight SNMP polling, and CPU usage depends on implementation. Option C is wrong because NETCONF typically uses XML (text) encoding, not binary encoding, while SNMP can use BER binary encoding. Option E is wrong because simple polling is characteristic of SNMP monitoring, whereas NETCONF is designed for configuration management and uses RPC-based sessions, not simple polling.

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Lower CPU usage on devices

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Binary data encoding

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Simple polling mechanism

Question 5

In the context of SDN, which API allows a network controller to communicate with the forwarding plane of network devices?

Accepted Answer

Southbound API. The Southbound API is used by an SDN controller to communicate with the forwarding plane (data plane) of network devices, such as switches and routers. It allows the controller to program the forwarding behavior of these devices. Northbound APIs are used for communication with applications, and eastbound/westbound APIs are used for controller-to-controller communication.

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Eastbound API

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Northbound API

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REST API

Question 6

At which layer of the OSI model do switches operate when forwarding frames based on MAC addresses?

Accepted Answer

Layer 2 (Data Link). Switches operate at Layer 2 (Data Link layer) because they use MAC addresses to forward frames.

Answer

Layer 1 (Physical)

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Layer 3 (Network)

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Layer 4 (Transport)

Question 7

An application sends a packet with destination IP 10.0.0.10. The sending host's routing table has a default gateway of 10.0.0.1. The host's ARP cache is empty. What is the next step after the host determines the packet should go to the default gateway?

Accepted Answer

Sends an ARP request for 10.0.0.1. When the host determines that the destination IP (10.0.0.10) is not on the same subnet and must be sent to the default gateway (10.0.0.1), it needs the gateway's MAC address to encapsulate the packet in a Layer 2 frame. Since the ARP cache is empty, the host must send an ARP request for the IP address of the default gateway (10.0.0.1) to obtain its MAC address before the packet can be forwarded.

Answer

Sends the packet to the DNS server

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Sends the packet directly to 10.0.0.10

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Sends an ARP request for 10.0.0.10

Question 8

A development team is implementing a microservices architecture. They need to ensure that services can discover each other dynamically without hardcoding IP addresses. Which technology should they use?

Accepted Answer

A service registry like Consul. A service registry like Consul provides a centralized directory where microservices register their network locations (IP and port) and health status. Other services query the registry to discover available instances dynamically, eliminating the need for hardcoded addresses. Consul supports health checks, multi-datacenter replication, and integrates with tools like Envoy for service mesh functionality.

Answer

A centralized load balancer

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An API gateway

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DNS-based service discovery

Question 9

A YANG module defines a leaf named 'bandwidth' of type 'uint32'. What does this represent in the context of a network device?

Accepted Answer

A single integer value representing bandwidth in kilobits per second. In YANG, a 'leaf' node defines a single, scalar value of a specific data type. When the leaf is named 'bandwidth' with type 'uint32', it represents a single integer value, typically interpreted as kilobits per second (kbps) in the context of network device configuration (e.g., interface bandwidth). This aligns with the standard YANG data modeling approach where a leaf cannot hold multiple values or complex structures.

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A set of unique bandwidth values

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A grouping of related bandwidth parameters

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An ordered list of bandwidth values

Question 10

A Kubernetes cluster is configured with a NetworkPolicy that allows ingress traffic only from pods with label 'app: frontend'. A new backend service needs to communicate with the database pod. What must be done to allow this?

Accepted Answer

Modify the NetworkPolicy to include an additional rule allowing from pods with label 'app: backend'. The existing NetworkPolicy only allows ingress from pods with label 'app: frontend'. To allow the backend service (which presumably has label 'app: backend') to communicate with the database pod, the best practice is to modify the existing NetworkPolicy to include an additional ingress rule that allows pods with label 'app: backend'. This preserves the existing security restrictions while permitting the new traffic. Deleting the policy (option A) would remove all ingress restrictions, which is less secure and not necessary unless explicitly required. Option B only adds a label to the database pod and does not affect the NetworkPolicy's source selection. Option D creates a new policy, but because NetworkPolicies are additive, the existing policy still denies traffic from the backend, so a new policy alone would not work unless it selects the same pod and explicitly allows the traffic; modifying the existing policy is simpler and more appropriate.

Answer

Delete the existing NetworkPolicy

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Add label 'app: backend' to the database pod

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Create a new NetworkPolicy for the database

Question 11

Match each JSON data type to its example.

Accepted Answer

String: "hello". JSON supports basic data types: string (e.g., "hello"), number (e.g., 42), boolean (true/false), null, array, and object. Common confusions include misidentifying boolean values as strings or strings as numbers.

Answer

String: true

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Number: "hello"

Question 12

What is the purpose of the Authorization header in a REST API call?

Accepted Answer

To authenticate the client sending the request. The Authorization header in an HTTP request carries credentials (such as a Bearer token, Basic auth, or API key) that the server uses to authenticate and authorize the client. It is the standard mechanism defined in RFC 7235 for transmitting authentication information with a REST API call.

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To specify the content type of the request body

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To specify the format of the response body

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To indicate the desired language

Question 13

Match each Cisco platform to its primary use case.

Accepted Answer

DNA Center: Centralized network management and automation. The correct matches are: DNA Center for centralized network management and automation, ISE for security policy and access control, and Meraki for cloud-managed networking. Common confusions include mixing up the management scope (DNA Center vs. Meraki) and security functions (ISE vs. DNA Center).

Answer

DNA Center: Security policy and access control

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ISE: Cloud-managed networking

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Meraki: Centralized network management and automation

Question 14

Match each Git command to its function.

Accepted Answer

git clone: Creates a copy of a repository from a remote source. Git clone creates a local copy of a remote repo; git commit records changes with a message; git push uploads commits; git pull fetches and merges. Common confusions include swapping clone with commit or push with pull.

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git clone: Records changes to the repository with a message

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git push: Fetches changes from a remote and merges them into the current branch

Question 15

A developer is designing an API that needs to support rate limiting per API key. The application is deployed on multiple instances. Which approach ensures consistent rate limiting across all instances?

Accepted Answer

Use a distributed cache like Redis. A distributed cache like Redis provides a shared, atomic counter that all application instances can read and increment, ensuring consistent rate limiting across a multi-instance deployment. Redis supports atomic operations like INCR and EXPIRE, which are essential for implementing sliding window or token bucket algorithms without race conditions.

Answer

Use a local in-memory counter

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Use a file-based lock

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Use environment variables