Cisco DevNet Associate 200-901 (200-901) — Questions 676–750

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Option A is wrong because `ios_ip_interface` is not a valid Ansible module; the correct module for managing interface IP addresses on IOS XE is `ios_l3_interface` or `ios_config`, not `ios_ip_interface`. Option B is wrong because `ios_command` is used to execute arbitrary show or exec commands on the device, not to apply configuration changes like setting an IP address. Option C is wrong because `ios_facts` is used to gather facts about the device (e.g., version, interfaces, neighbors), not to modify configuration.

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Option A is wrong because DELETE is idempotent but removes the resource, not updates it. Option C is wrong because PATCH is not guaranteed to be idempotent; it applies partial modifications that may depend on the current state of the resource. Option D is wrong because POST is not idempotent; it typically creates a new resource or triggers a non-idempotent action, and repeated requests may create multiple resources or cause different outcomes.

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Option B is wrong because gRPC streaming is a generic transport mechanism that can be used in both dial-in and dial-out modes, but it does not specify which side initiates the connection. Option C is wrong because streaming pull is a mode where the collector initiates the connection and requests data from the device, not the device pushing data. Option D is wrong because dial-in mode requires the collector to initiate the connection to the device, which is the opposite of the scenario described.

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Option B (Git) is wrong because Git is a distributed version control system for tracking source code changes, not an infrastructure-as-code tool for automating configuration management. Option C (Python) is wrong because Python is a general-purpose programming language that requires imperative scripting to manage configurations, lacking the declarative language model and built-in multi-device automation of Ansible. Option D (Postman) is wrong because Postman is an API testing and development tool, not designed for infrastructure-as-code or configuration management across devices.

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Option A is wrong because runts are frames smaller than the minimum 64-byte size (for Ethernet) and are typically caused by collisions or underruns, but they are not the direct counter for confirming collisions; CRC errors are more definitive. Option C is wrong because output errors encompass a variety of issues such as buffer failures, underruns, and late collisions, but they are not specific to collisions themselves and can be misleading. Option D is wrong because giants are frames larger than the maximum 1518-byte size (for standard Ethernet) and are usually caused by misconfigured NICs or software issues, not collisions.

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Option A is wrong because an invalid access token would result in a 401 Unauthorized error, not a 400 Bad Request. Option C is wrong because a network connectivity issue would typically cause a timeout or connection refused error, not an HTTP 400 response from the server. Option D is wrong because the Webex Teams API allows duplicate room names; a 400 error would not occur for a name that already exists.

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Option B (ios_command) is wrong because it sends raw CLI commands and does not enforce idempotency; it blindly executes commands without checking current state, which can cause errors or duplicate configurations. Option C (ios_config) is wrong because it manages arbitrary configuration lines as a whole, not VLAN-specific resources; it can be used to push VLAN commands but lacks the idempotent, declarative VLAN handling that ios_vlan provides (e.g., it does not parse existing VLAN state to avoid re-adding). Option D (ios_interface) is wrong because it manages interface properties (e.g., switchport mode, access VLAN) but does not create, delete, or modify VLAN definitions themselves.

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Option B (MVC) is wrong because it is a UI design pattern that separates an application into Model, View, and Controller components; it does not address inter-service asynchronous communication. Option C (RESTful API) is wrong because REST typically uses synchronous HTTP request-response calls, which would require the discovery service to wait for each notification to complete, violating the asynchronous requirement. Option D (Monolithic architecture) is wrong because it packages all functionality into a single deployable unit, which contradicts the microservices-based design and makes independent scaling and asynchronous notification difficult.

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Option B (ICMP) is wrong because ICMP is a network layer protocol used for error reporting and diagnostic functions (e.g., ping), not for transporting application data like HTTP. Option C (IP) is wrong because IP is a network layer protocol responsible for addressing and routing packets, not for reliable delivery at the transport layer. Option D (UDP) is wrong because UDP is a transport layer protocol that provides connectionless, unreliable delivery without acknowledgments or retransmissions, making it unsuitable for HTTP's requirement of guaranteed delivery.

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Option A is wrong because passing the token as a query parameter named 'token' is insecure and not supported by the Cisco DNA Center API; tokens should never be exposed in URLs due to logging and caching risks. Option B is wrong because placing the token in the request body would require a specific API endpoint to accept it that way, but the standard for RESTful APIs like DNA Center is to use headers, not the body, for authentication. Option D is wrong because although Bearer tokens in the Authorization header are common in OAuth 2.0, the Cisco DNA Center API specifically requires the X-Auth-Token header, not the Authorization header; using the wrong header will result in an authentication failure.

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Option B is wrong because RUN cd /app only changes the directory for that single RUN command; it does not persist for subsequent instructions like COPY, CMD, or ENTRYPOINT. Option C is wrong because ENV sets an environment variable named WORKDIR with the value /app, but it does not change the working directory for Dockerfile instructions; the WORKDIR instruction must be used explicitly.

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Option B is wrong because the POST /dna/intent/api/v1/site endpoint is the correct API for creating sites under a parent; using a different endpoint would not create the site at all. Option C is wrong because the 'siteId' header is not required for this API call; the parentId is provided in the JSON payload, and missing headers would cause an authentication or request error, not a misplacement. Option D is wrong because the 'address' field is not required for creating an 'area' type site; it is only required for 'building' type sites, and the script's payload correctly omits it for an area.

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Option A is wrong because the A record maps a domain name to a 32-bit IPv4 address, not an IPv6 address. Option C is wrong because the CNAME record creates an alias from one domain name to another canonical name, it does not store any IP address. Option D is wrong because the MX record specifies the mail exchange server responsible for accepting email on behalf of a domain, and it contains a hostname, not an IP address.

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Option A is wrong because invalid JSON in the request body would typically result in a 400 Bad Request error, not a 401 Unauthorized. Option C is wrong because an incorrect API base URL would cause a connection failure (e.g., DNS resolution error or 404 Not Found), not a 401 status code. Option D is wrong because a missing Accept header might lead to a 406 Not Acceptable or a default response format, but it does not trigger authentication failure.

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Option A is wrong because retrying with a fixed delay can cause synchronized retry storms (thundering herd) that overwhelm the ACI APIC controller, especially during transient outages. Option B is wrong because ignoring errors and continuing can lead to silent data corruption or missed state changes in the ACI fabric, violating the principle of reliable API consumption. Option C is wrong because always retrying immediately does not give the server time to recover from transient failures and can exacerbate congestion, leading to cascading failures.

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Option A is wrong because the Credentials Plugin manages authentication credentials (e.g., usernames, passwords, SSH keys) but does not provide any Docker-specific build or push functionality. Option B is wrong because the Pipeline Plugin is the core plugin that enables defining Jenkins pipelines as code, but it lacks built-in Docker steps; it requires additional plugins like the Docker Pipeline Plugin to handle Docker operations. Option D is wrong because the Git Plugin integrates Git SCM operations (e.g., checkout, fetch) into Jenkins jobs, but it has no capability to build or push Docker images.

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Option A is wrong because encrypting the Ansible vault password protects secrets (e.g., credentials) but does not control who can trigger the pipeline or authorize changes to production devices. Option C is wrong because a separate staging environment validates configurations before production but does not enforce authorization on who can trigger the production deployment. Option D is wrong because a pre-commit hook in Git validates YAML syntax locally, which prevents malformed files but does not provide any access control over who can initiate the CI/CD pipeline or deploy to production.

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Option B is wrong because a rate limit exceeded would return a 429 HTTP status (Too Many Requests), not 401. Option C is wrong because permission issues (e.g., insufficient scope) typically result in a 403 Forbidden status, not 401 Unauthorized. Option D is wrong because an incorrect endpoint URL would return a 404 Not Found or a different error, not a 401; the 401 specifically points to authentication failure, not routing issues.

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Option A is wrong because regression testing re-runs previously passed tests to ensure new changes haven't broken existing functionality; it does not specifically target interactions in a simulated environment. Option B is wrong because unit testing validates individual functions or modules in isolation (e.g., a single Ansible playbook or a single CLI command), not the interaction of multiple network devices. Option D is wrong because smoke testing is a shallow, quick check of critical functionality (e.g., 'does the router respond to ping?') to decide whether to proceed with deeper testing, not a comprehensive test of integrated components.

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Option A is wrong because storing secrets in an encrypted SSH key file does not address encryption of the inventory files themselves; SSH keys are used for authentication, not for encrypting variables in inventory. Option B is wrong because setting file permissions to 0600 only restricts file system access but does not encrypt the data; secrets remain in plaintext and could be read by any process with sufficient privileges or during backup. Option C is wrong because environment variables are not encrypted at rest; they are stored in plaintext in process memory and can be exposed via /proc filesystem or logging, and they do not provide encryption for the inventory files.

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Option A is wrong because the PUT request already targets the correct YANG path and format; the issue is not about nesting or format but about committing the candidate datastore. Option B is wrong because rebooting the switch would discard the uncommitted candidate configuration and is unnecessary; the candidate datastore persists across reboots only if explicitly saved, but the commit operation is the standard method to apply changes. Option D is wrong because MTU is irrelevant to the RESTCONF commit process; the payload size for a VLAN configuration is well within typical MTU limits, and the 201 response confirms the payload was received successfully.

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Option A is wrong because if the public key format were incorrect, the switches would reject the key during authentication, but the engineer verified the key is correctly deployed via console, and the same key works on other switches. Option B is wrong because the become method controls privilege escalation (e.g., to enable mode) on the target device, not SSH authentication; the error 'Authentication failed' occurs at the SSH transport layer, before any become operation. Option D is wrong because unreachable switches would produce a 'Host unreachable' or 'Connection timed out' error, not 'Authentication failed'; the error message specifically indicates the SSH handshake failed due to credentials.

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Option A is wrong because `pass` is a null operation that does nothing; it is used as a placeholder in loops, conditionals, or function bodies, but it does not define a function. Option B is wrong because `yield` is used inside a generator function to produce a sequence of values lazily, and it does not define the function itself. Option C is wrong because `return` is used to exit a function and optionally pass a value back to the caller; it is not the keyword that defines the function.

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Option A is wrong because Cisco NX-API does not support Bearer token authentication; it relies on a session cookie (APIC-cookie) set during login. Option B is wrong because the HTTP method (GET vs PUT) does not affect authentication; the 401 error is due to missing credentials, not the request type. Option D is wrong because retrieving VLAN configuration is a read operation that should use GET, not POST; POST is used for creating resources or sending payloads, not for fetching data.

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Option A is wrong because the DHCP server being 'not authoritative' affects lease assignment and renewal behavior (e.g., sending DHCPNAK for unknown clients), but does not prevent the router from obtaining an IP address or downloading the bootfile; the router already has an IP address, so this is not the issue. Option C is wrong because if the TFTP server IP were unreachable, the router would not be able to download any file, but the question states the device obtains an IP address and the DHCP logs show option 150 is set; the issue is specifically that the script is not executed, which points to a file mismatch rather than connectivity. Option D is wrong because Cisco routers that support ZTP (e.g., IOS-XE devices) are designed to use DHCP options 67 and 150 for automated provisioning; if the router did not support ZTP, it would not even attempt to download the script, but the question implies the router is capable and the failure is in execution.

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Option A is wrong because Jenkins uses a `Jenkinsfile` (typically Groovy-based) and does not read YAML files from `.github/workflows`; it requires its own server or agent configuration. Option B is wrong because CircleCI uses a `.circleci/config.yml` file placed in the `.circleci` directory, not `.github/workflows`. Option D is wrong because GitLab CI uses a `.gitlab-ci.yml` file placed in the root of the repository, not in a `.github/workflows` directory, and is designed for GitLab repositories, not GitHub.

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Option A is wrong because VLAN configuration affects Layer 2 connectivity and trunking, not the administrative state of a routed interface; an interface can be administratively down even with correct VLAN settings. Option B is wrong because a duplicate IP address would cause a conflict or error message, but it would not prevent the interface from being administratively enabled; the 'no shutdown' command is still required. Option C is wrong because a faulty interface would typically show as 'down/down' or have CRC errors, not 'administratively down'; the administrative state is a software-controlled flag, not a hardware fault.

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Option A is wrong because `docker exec` runs a command in an already running container, not a new temporary container. Option B is wrong because `docker run -d` runs a container in detached mode in the background, intended for long-running services, not a one-off command that exits. Option C is wrong because `docker start` restarts an existing stopped container, not a new temporary container.

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Option A is wrong because 'serial' is a unique hardware identifier for the device and does not indicate cloud connectivity status. Option B is wrong because 'lanIp' shows the local IP address assigned to the device on the LAN, which can be present even if the device is offline or disconnected from the cloud. Option D is wrong because 'model' specifies the hardware model (e.g., MR42) and has no bearing on the device's current cloud connection state.

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Option A is wrong because the /api/system/v1/auth/token endpoint requires a POST method with Basic Authentication, not a GET; if the script used GET, it would get a 405 Method Not Allowed, not a 401. Option B is wrong because the script is using /v1 which is the correct version for token generation; using /v2 would return a 404 Not Found, not a 401. Option C is wrong because CORS is a browser-enforced security mechanism that blocks cross-origin HTTP requests from JavaScript in a web page, not from a Python script running on a server or CLI; a Python script is not subject to CORS restrictions.

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Option B (tuple) is wrong because a tuple is an ordered, immutable collection that allows duplicate elements, not an unordered unique set. Option C (list) is wrong because a list is an ordered, mutable collection that permits duplicates and maintains insertion order. Option D (dict) is wrong because a dictionary stores key-value pairs with unique keys, but it is not a collection of elements; it maps keys to values and is unordered (in Python <3.7) or insertion-ordered (Python ≥3.7), not a simple set of unique items.

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Option A is wrong because `def func(args):` defines a function that accepts exactly one positional argument named `args`, not a variable number. Option B is wrong because `def func(args*):` is invalid Python syntax; the asterisk must precede the parameter name (i.e., `*args`), not follow it. Option C is wrong because `def func(**kwargs):` accepts a variable number of keyword arguments (collected into a dictionary), not positional arguments.

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Option B is wrong because an ACL blocking traffic from the branch subnet would typically prevent the initial outbound traffic from the branch, but users at the branch can already access the internet, indicating no such ACL is blocking general traffic; additionally, the ping from HQ to BR succeeds, suggesting no ACL is blocking ICMP. Option C is wrong because the default route on BR is correctly pointing to HQ's IP address, as evidenced by the branch's ability to reach the internet through HQ. Option D is wrong because the T1 link is up/up and the ping from HQ to BR is successful, which rules out significant link errors or packet loss that would affect connectivity.

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Option A is wrong because CSRF tokens protect against cross-site request forgery, not SQL injection; they prevent unauthorized commands from being executed on behalf of an authenticated user. Option B is wrong because output encoding (e.g., HTML entity encoding) is used to prevent cross-site scripting (XSS) by escaping data before rendering in a browser, not for securing database queries. Option C is wrong because input validation alone is insufficient; it can be bypassed (e.g., via encoded payloads or logic flaws) and does not address the root cause of SQL injection, which is the mixing of code and data in a query string.

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Option A is wrong because the Authorization Code Grant without PKCE (or without OIDC) only returns an access token, not an ID token with user claims; it is designed for authorization, not authentication. Option C is wrong because the Resource Owner Password Grant directly exchanges user credentials for an access token, but it does not include an ID token and is deprecated due to security risks (RFC 6749 Section 4.3). Option D is wrong because the Client Credentials Grant is used for server-to-server communication without a user context, so it never returns an ID token or user claims.

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Option A is wrong because the 'vpn' field is not optional for setting a VPN label; VPN labels are typically assigned via MPLS label operations or separate label-switching configurations, not via a route object's 'vpn' field. Option B is wrong because it does not define the transport VPN for traffic from this VPN; transport VPNs are defined by separate VRF or MPLS transport constructs, not by a per-route field. Option C is wrong because it does not specify the VPN that the route belongs to; the route's own VPN is usually implied by the VRF or routing context in which the route is defined, not by a field pointing to a next-hop VPN.