Examkin

Automation and Programmability

200 questions

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Question 101Question →

A network automation engineer is creating a script to manage device configurations via a Cisco RESTful API. Which two statements accurately describe the operational characteristics of HTTP verbs and request headers in this REST-based architecture?

Select all that apply

Show answer & explanation

Answer: An HTTP PUT request sent to a configuration resource endpoint replaces the target resource in its entirety with the payload supplied in the request.; The Content-Type request header communicates to the REST API server the specific data serialization format used within the request body.

Answer

The two correct statements are that an HTTP PUT request replaces the target resource in its entirety with the provided payload, and the Content-Type request header specifies the serialization format of the request body.
In RESTful web services, HTTP PUT maps to replacing an existing resource in its entirety with the payload sent by the client. Additionally, the Content-Type request header explicitly tells the API server how to deserialize the incoming payload format (e.g., application/json).

Step-by-Step Solution

1
Analyze the functional behavior of HTTP PUT versus HTTP PATCH in RESTful architectures.
HTTP PUT performs a complete replacement (Update/Create) of the target resource using the provided payload. Conversely, HTTP PATCH performs a partial update, updating only the attributes included in the request payload.
Understanding resource replacement mechanics prevents accidental loss of configuration parameters during API calls.
2
Evaluate the idempotency characteristics of HTTP verbs.
HTTP GET, PUT, and DELETE are idempotent because executing them repeatedly produces the same server state. HTTP POST is non-idempotent because consecutive requests typically instantiate duplicate resources.
Differentiating idempotent operations ensures script execution safety and predictable API interactions.
3
Examine HTTP header roles for payload processing.
The Content-Type header indicates the format (such as JSON or XML) of the data being sent to the server in the request body, whereas the Accept header specifies the data format expected in the response body.
Proper header specification allows the client and server to negotiate content serialization correctly.

Key Concept

REST API HTTP Verbs (CRUD operations, idempotency, PUT vs PATCH) and HTTP Headers (Content-Type vs Accept)
Question 102Question →

Match each architectural concept to its corresponding description within traditional and controller-based networking environments.

Click a left item, then click its matching right item

Items

Southbound Interface (SBI)
Northbound Interface (NBI)
Distributed Control Plane
Centralized Control Plane

Matches

Show answer & explanation

Answer

Southbound Interface pairs with communication between controller and forwarding elements via protocols like NETCONF/OpenFlow. Northbound Interface pairs with RESTful API communication between controller and applications. Distributed Control Plane pairs with autonomous per-device processing. Centralized Control Plane pairs with consolidated global topology control.
The correct pairings accurately map interface directions and control plane locations: Southbound Interfaces interact downwards with physical or virtual network devices via protocols such as NETCONF, RESTCONF, or OpenFlow; Northbound Interfaces interact upwards with applications and management suites using REST APIs; Distributed Control Planes compute logic independently per device; and Centralized Control Planes aggregate network intelligence into a controller to manage policies centrally.

Step-by-Step Solution

1
Identify controller communication directionality (Northbound vs. Southbound).
Northbound interfaces point up toward applications/REST APIs; Southbound interfaces point down toward network switches/routers using protocols like NETCONF, RESTCONF, or OpenFlow.
Establishing API directional planes differentiates controller-based interface functions.
2
Differentiate control plane placement (Distributed vs. Centralized).
Traditional distributed control planes compute routing tables locally on every switch/router, whereas controller-based centralized control planes consolidate network logic within a central controller.
Locating control plane logic is the fundamental structural distinction between traditional and SDN-based network architectures.

Key Concept

Architectural Plane and Interface Separation in Traditional vs. Controller-Based Networks
Question 103Question →

A network engineer performs an HTTP GET request to a Cisco IOS XE RESTCONF interface configuration endpoint. The server returns the following JSON payload:

{
"ietf-interfaces:interfaces": {
"interface": [
{
"name": "GigabitEthernet0/0/0",
"type": "iana-if-type:ethernetCsmacd",
"enabled": "true",
"ietf-ip:ipv4": {
"address": [
{
"ip": "192.168.10.1",
"netmask": "255.255.255.0"
}
]
}
},
{
"name": "GigabitEthernet0/0/1",
"type": "iana-if-type:ethernetCsmacd",
"enabled": false,
"ietf-ip:ipv4": {
"address": [
{
"ip": "10.0.1.1",
"netmask": "255.255.255.252"
}
]
}
}
]
}
}

Which TWO statements accurately interpret the structure and data types in this JSON payload?

Select all that apply

Show answer & explanation

Answer: The key path payload["ietf-interfaces:interfaces"]["interface"][0]["enabled"] evaluates to a String data type rather than a Boolean primitive.; The path expression payload["ietf-interfaces:interfaces"]["interface"][1]["ietf-ip:ipv4"]["address"][0]["ip"] resolves to the IP address "10.0.1.1".

Answer

The statement identifying the 'enabled' key in the first interface as a String data type and the path navigating to '10.0.1.1' using array index [1] and address index [0] are both correct.
The option noting that the 'enabled' key contains a String is correct because the value is enclosed in quotes ("true"). The option identifying the path to '10.0.1.1' is correct because index [1] accesses the second interface (GigabitEthernet0/0/1) in zero-indexed JSON array navigation.

Step-by-Step Solution

1
Analyze data types for the 'enabled' key in GigabitEthernet0/0/0.
The value is wrapped in double quotes ("true"), signifying a string primitive in JSON syntax, unlike GigabitEthernet0/0/1 which uses an unquoted boolean literal (false).
Quotations differentiate string values from boolean keywords in JSON parsing.
2
Trace the array index and dictionary path to locate IP address '10.0.1.1'.
The root dictionary has key 'ietf-interfaces:interfaces' -> key 'interface' (list) -> index [1] (second element GigabitEthernet0/0/1) -> key 'ietf-ip:ipv4' (object) -> key 'address' (list) -> index [0] (first element) -> key 'ip' returns '10.0.1.1'.
JSON arrays start at index 0, so index 1 selects the second item in the list.
3
Evaluate the remaining choices against JSON syntax rules.
The 'address' key holds square brackets [], which denote a list/array, not a dictionary object {}. Index [0] on 'interface' yields GigabitEthernet0/0/0, not GigabitEthernet0/0/1.
Square brackets define ordered arrays and zero-indexing governs list positioning.

Key Concept

Interpreting JSON Encoded Data Types and Nested Structure Navigation
Estimated Time:2m 0s
Question 104Question →

Following an infrastructure audit, a network administrator discovers that Quality of Service (QoS) class maps and policy configurations differ significantly across 50 access switches because they were configured individually via manual CLI commands. Which capability of a controller-based network architecture directly addresses and resolves this operational challenge?

Show answer & explanation

Answer: The centralized network controller abstracts device configurations into enterprise intent policies and provisions managed devices consistently using Southbound APIs.

Answer

The central network controller maintains an intent-based policy model and deploys consistent configuration settings across network elements using Southbound APIs.
In traditional networks, each device is managed individually using distributed control and management planes (typically via CLI or SNMP), leading to configuration drift over time. In a controller-based architecture, the network administrator specifies high-level business intent on a centralized controller. The controller then translates this intent into specific device configurations and pushes them downstream using Southbound APIs (such as NETCONF, RESTCONF, or OpenFlow), ensuring complete consistency across all network elements.

Step-by-Step Solution

1
Identify the core operational problem in the scenario
Manual, per-device CLI configuration leads to configuration drift and inconsistent policies across multiple switches.
Traditional networking relies on distributed management where each device is logged into and configured independently.
2
Analyze how controller-based SDN models handle management and configuration distribution
The controller centralizes management and control logic, allowing administrators to express business intent centrally.
Centralization removes the need for individual CLI configuration on each node.
3
Determine the role of APIs in enforcing consistent network policies
Southbound APIs (e.g., NETCONF, RESTCONF) allow the controller to communicate down to the switches to enforce uniform policy.
Southbound protocols interface between the SDN controller's control plane/management layer and the physical data plane devices.

Key Concept

Centralized abstraction and policy enforcement via Southbound APIs in SDN architecture vs. distributed per-device CLI management in traditional networking.
Question 105Question →

Match each configuration management tool on the left with its corresponding operational traits, communication protocols, and file terminology on the right.

Click a left item, then click its matching right item

Items

Ansible
Puppet
Chef

Matches

Show answer & explanation

Answer

Ansible matches with the agentless push architecture using YAML Playbooks over SSH/NETCONF. Puppet matches with the pull model using Puppet DSL Manifests over TCP port 8140. Chef matches with the pull model using Ruby-based Recipes and Cookbooks over TCP port 443.
Ansible is distinct for its agentless push model using SSH and YAML Playbooks. Puppet operates via an agent pull model requesting Manifests over TCP 8140. Chef operates via an agent pull model fetching Ruby-based Recipes and Cookbooks over HTTPS (TCP 443).

Step-by-Step Solution

1
Identify the agent requirement and transport protocol for each tool.
Ansible is agentless (SSH/NETCONF), while Puppet (TCP 8140) and Chef (TCP 443) require client agent software.
Agentless operation is a unique distinguishing operational characteristic of Ansible.
2
Determine the data encoding format or domain-specific language (DSL) used by each tool.
Ansible uses YAML, Puppet uses Puppet DSL, and Chef uses Ruby-based DSL.
File formats directly map to tool-specific terminology and structures.
3
Associate file names and operational direction with each tool.
Ansible uses Playbooks (Push), Puppet uses Manifests (Pull), and Chef uses Recipes/Cookbooks (Pull).
Matching push vs pull and configuration artifact naming establishes complete tool identification.

Key Concept

Capabilities and Architectural Traits of Configuration Management Tools (Ansible, Puppet, Chef)
Question 106Question →

A network monitoring portal issues an HTTP request to a Cisco DNA Center REST API endpoint to update the syslog server configuration on a managed switch. The request payload contains only the key-value pair for the primary syslog server IP address. After the API execution completes, an engineer discovers that the secondary syslog server IP address and logging severity level settings were erased and reset to defaults. Which HTTP method was executed by the portal to cause this behavior?

Show answer & explanation

Answer: HTTP PUT

Answer

HTTP PUT is the method executed because it replaces the entire target resource payload, resetting omitted fields to their default state.
The HTTP PUT method maps to the Update/Replace CRUD operation. In RESTful API architectures, sending an HTTP PUT request requires representing the full resource. If an API call provides only a subset of resource fields, the server replaces the whole object, leaving unmentioned properties unassigned or set back to default values.

Step-by-Step Solution

1
Analyze the operational outcome described in the scenario.
The target configuration was updated, but omitted fields (secondary syslog IP and logging severity) were removed and reset to default values.
Understanding how different HTTP verbs handle missing payload attributes is critical in REST API interactions.
2
Compare HTTP update verbs (PUT vs. PATCH).
HTTP PUT is specified as a full resource replacement (Update/Replace), whereas HTTP PATCH is defined as a partial update (Modify).
Sending a partial payload with HTTP PUT forces the API server to overwrite the existing resource with the provided fields and set unspecified fields to null or default values.

Key Concept

Operational Differences Between HTTP PUT and HTTP PATCH in REST APIs
Question 107Question →

An engineer is developing a Python script to interact with the Cisco DNA Center REST API to audit device configurations and modify global settings. Which two statements accurately describe the operational characteristics of HTTP request headers and HTTP verbs used in this REST API environment?

Select all that apply

Show answer & explanation

Answer: The Accept HTTP header specifies the media type (such as application/json) that the client expects to receive in the response from the server.; HTTP PUT operations are idempotent, meaning executing identical requests multiple times results in the same final state on the server.

Answer

The statement explaining that the Accept header specifies the expected response format and the statement noting that HTTP PUT operations are idempotent are both correct.
The Accept HTTP header is used by the client during request negotiation to specify the payload format (e.g., JSON or XML) expected in the server response. Additionally, HTTP PUT operations are inherently idempotent; submitting the exact same request body multiple times produces the same server state as a single invocation.

Step-by-Step Solution

1
Analyze HTTP request headers for REST APIs
Content-Type specifies the format of the payload being sent in the request (e.g., application/json), while Accept specifies the media type the client expects in the server's response.
Headers define negotiation rules between the client and API server.
2
Analyze HTTP verb characteristics and idempotency
PUT (used to Create/Replace) and GET, DELETE, OPTIONS are idempotent. POST (used to Create subordinate resources) is non-idempotent because multiple identical calls produce side effects such as duplicate entries.
Idempotency defines whether making multiple identical calls alters the server state beyond the initial call.

Key Concept

HTTP headers (Content-Type vs Accept) and verb properties (Idempotency of PUT vs POST)
Question 108Question →

A network operations engineer is documenting the architectural changes associated with migrating an enterprise infrastructure from a traditional distributed routing model to a software-defined controller-based network architecture. Which of the following statements correctly describe operational or structural differences introduced by controller-based networking? (Select TWO.)

Select all that apply

Show answer & explanation

Answer: Control plane intelligence is centralized within the software controller, relieving individual underlying network devices from calculating global topology maps independently.; Southbound APIs enable the centralized controller to dynamically communicate with and program forwarding behaviors on network infrastructure devices.

Answer

The correct statements are that control plane intelligence is centralized within the software controller to relieve individual devices from computing global topology maps independently, and that Southbound APIs enable the controller to dynamically program network infrastructure devices.
In controller-based networking, the centralized controller aggregates control plane logic, freeing individual routers and switches from executing distributed control algorithms individually. To push changes down to the infrastructure layer, the controller uses Southbound protocols and APIs (such as OpenFlow, NETCONF, or RESTCONF).

Step-by-Step Solution

1
Analyze the role of the control plane in traditional vs controller-based networks.
In traditional networks, each node runs distributed control plane protocols (e.g., OSPF, EIGRP). In controller-based networks, control plane processing is centralized within the controller.
Centralization reduces node overhead and establishes a centralized view of the network fabric.
2
Evaluate the interface roles (Northbound vs Southbound APIs).
Southbound APIs connect the controller to network devices (underlay/nodes), allowing configuration and policy distribution down to the data plane.
Northbound APIs communicate upward to applications and management orchestration platforms, while Southbound APIs talk downward to network elements.
3
Identify misstatements regarding configuration management tools and REST API verbs.
Ansible is agentless (using SSH), whereas Puppet and Chef generally rely on installed agents. Additionally, HTTP GET reads data, while HTTP POST creates data.
Misidentifying agent requirement profiles or HTTP CRUD mappings represents common conceptual errors in network automation.

Key Concept

Centralized vs. Distributed Control Planes & SDN Interfaces (Southbound vs Northbound)
Estimated Time:1m 30s
Question 109Question →

When interacting with RESTful network APIs, network engineers use specific HTTP request verbs to execute CRUD (Create, Read, Update, Delete) operations against management endpoints. Match each HTTP request verb on the left to its corresponding operational behavior on the right.

Click a left item, then click its matching right item

Items

HTTP POST
HTTP GET
HTTP PUT
HTTP PATCH
HTTP DELETE

Matches

Show answer & explanation

Answer

HTTP POST matches creating a new subordinate resource; HTTP GET matches retrieving data safely; HTTP PUT matches full resource replacement; HTTP PATCH matches partial field modification; HTTP DELETE matches resource removal.
Each HTTP verb corresponds directly to a standard CRUD action in RESTful architectures. POST creates new entries, GET reads existing data, PUT overwrites/replaces entire resources, PATCH updates specific fields partially, and DELETE erases targeted resources.

Step-by-Step Solution

1
Identify the mapping between HTTP POST and CRUD operations.
HTTP POST performs the Create operation by instantiating new data resources under a collection URI.
POST is used for creating new entries when the client does not specify the exact final resource URI.
2
Identify the mapping between HTTP GET and CRUD operations.
HTTP GET performs the Read operation by retrieving data without making changes.
GET requests are read-only, safe, and idempotent.
3
Distinguish between HTTP PUT and HTTP PATCH for Update operations.
HTTP PUT performs a full update (replacement), whereas HTTP PATCH performs a partial update.
PUT overwrites the entire target resource with the provided payload, whereas PATCH only modifies specified key-value pairs.
4
Identify the mapping between HTTP DELETE and CRUD operations.
HTTP DELETE performs the Delete operation.
DELETE instructs the API endpoint to erase the target resource.

Key Concept

RESTful API HTTP verbs map directly to basic database CRUD operations (POST=Create, GET=Read, PUT/PATCH=Update, DELETE=Delete).
Question 110Question →

An administrator creates a new syslog server destination entry using a REST API endpoint on a network controller. Shortly after, the administrator needs to modify only the port number parameter for this existing log server entry, while preserving all other existing attributes without re-submitting the full resource payload. Which HTTP request verb and body approach should be utilized to perform this specific modification?

Show answer & explanation

Answer: HTTP PATCH with a payload containing only the port number key-value pair

Answer

HTTP PATCH with a payload containing only the port number key-value pair
In REST-based API design, the HTTP PATCH method is used to perform partial updates on an existing resource. When sending a PATCH request, the body contains only the specific key-value pairs that need to be changed, leaving all unmentioned parameters in their current state on the server.

Step-by-Step Solution

1
Identify the CRUD operation required for modifying a specific subset of fields on an existing resource.
The requirement calls for a partial update rather than a full resource replacement or creation.
The scenario explicitly states that only the port number should be modified while preserving all other existing attributes without resending the entire configuration.
2
Map the partial update operation to the corresponding RESTful HTTP verb.
HTTP PATCH is selected because it applies updates only to the fields included in the request body.
HTTP PUT replaces the resource entirely (omitted fields are lost/reset), whereas HTTP PATCH applies incremental or partial changes.

Key Concept

HTTP PATCH vs. PUT operations in REST APIs
Question 111Question →

An enterprise engineering team is preparing to migrate a legacy multi-tier campus network to a centralized controller-based architecture using Cisco DNA Center. During an architectural review, an engineer explains how control plane operations and management differ between the two paradigms. Which statement correctly contrasts control plane operations in a traditional network versus a controller-based network architecture?

Show answer & explanation

Answer: Traditional networks execute control plane logic independently on each distributed network device, whereas controller-based networks centralize control plane intelligence within a logical software controller.

Answer

Traditional networks execute control plane logic independently on each distributed network device, whereas controller-based networks centralize control plane intelligence within a logical software controller.
In traditional network environments, each router and switch runs its own distributed control plane to independently discover neighbors, build routing/switching tables, and determine path selection. In contrast, controller-based networking decouples control plane intelligence from individual network devices and centralizes it within a software controller (such as Cisco DNA Center), which programs the data plane of underlying network devices.

Step-by-Step Solution

1
Analyze control plane distribution in traditional network architectures.
In traditional networking, each network device operates with a localized control plane, independently computing routing tables, spanning-tree topologies, and MAC tables.
Traditional devices must run control plane protocols locally on each physical unit.
2
Analyze control plane distribution in controller-based network architectures.
Controller-based networks abstract and centralize the control plane into a software-defined controller (such as Cisco DNA Center), which maintains a global view of the network and instructs hardware devices via Southbound APIs.
Decoupling and centralizing control plane intelligence provides automated provisioning and global network policy enforcement.
3
Identify the option that accurately describes this architectural difference.
The statement highlighting that traditional networks execute control plane logic locally on distributed devices while controller-based networks centralize control plane intelligence within a logical controller is correct.
This captures the fundamental shift from distributed control plane processing to centralized controller intelligence.

Key Concept

Decoupling and Centralization of Control Plane in SDN vs Distributed Traditional Control Plane
Question 112Question →

A network operations team is reviewing the architectural layers of a newly deployed software-defined campus fabric. They need to ensure that the physical infrastructure properly supports endpoint encapsulation and tunneled communication across the fabric. Which of the following best describes the primary function of the underlay network in this software-defined architecture?

Show answer & explanation

Answer: Providing underlying physical IP connectivity and routing between fabric nodes using protocols like OSPF or IS-IS to transport overlay packets

Answer

Providing underlying physical IP connectivity and routing between fabric nodes using protocols like OSPF or IS-IS to transport overlay packets
The correct option accurately identifies the underlay network's role: establishing baseline physical layer IP reachability and routing across switches using traditional routing protocols (e.g., OSPF, IS-IS), allowing overlay encapsulated packets to be transported between nodes.

Step-by-Step Solution

1
Identify the role of the Underlay layer in an SDN fabric
The underlay consists of physical switches, routers, cabling, and routing protocols responsible purely for point-to-point IP connectivity between nodes.
Without reliable IP reachability provided by the underlay, overlay tunneling protocols (such as VXLAN) cannot form tunnels between endpoints (VTEPs).
2
Distinguish Underlay responsibilities from Overlay responsibilities
The overlay handles network virtualization, encapsulation (e.g., VXLAN), and mapping (e.g., LISP), running on top of the underlay infrastructure.
Clear separation between underlay transport and overlay service delivery allows overlay networks to scale independently of the physical topology.

Key Concept

Underlay vs. Overlay in Software-Defined Architectures
Question 113Question →

Match each software-defined architecture component or protocol on the left with its corresponding operational role within a Cisco enterprise fabric on the right.

Click a left item, then click its matching right item

Items

VXLAN
LISP
Underlay Network
Cisco DNA Center

Matches

Show answer & explanation

Answer

VXLAN pairs with data plane frame encapsulation via UDP tunnels; LISP pairs with control plane mapping of EIDs to RLOCs; Underlay Network pairs with physical connectivity and Layer 3 IP routing reachability; Cisco DNA Center pairs with centralized management plane orchestration and policy automation.
VXLAN handles data plane encapsulation by tunneling Layer 2 Ethernet frames over Layer 3 UDP headers. LISP functions as the fabric control plane mapping protocol connecting EIDs to RLOCs. The underlay network consists of the physical devices and IP routing protocols that provide base reachability across switches. Cisco DNA Center serves as the centralized management controller responsible for network automation, provisioning, and policy management.

Step-by-Step Solution

1
Identify the data plane overlay tunneling mechanism.
VXLAN uses MAC-in-UDP encapsulation to build overlay tunnels across Layer 3 boundaries.
Overlay data planes require encapsulating original host frames so they can cross intermediate routed infrastructure transparently.
2
Identify the control plane protocol responsible for host mapping.
LISP maintains the mapping database connecting host IP/MAC addresses (EIDs) to their switch location (RLOCs).
Separating host location from identity minimizes flooding and enables endpoint mobility.
3
Identify the infrastructure base supporting overlay communication.
The underlay network provides basic IP routing connectivity between physical switch interfaces.
Fabric nodes must establish IP reachability via IGP routing protocols prior to forming overlay tunnels.
4
Identify the centralized management platform.
Cisco DNA Center manages policy, orchestration, and provisioning across the fabric.
Management plane platforms aggregate controller operations into a single interface for intent-based network management.

Key Concept

Software-Defined Architectures: Overlay, Underlay, and Fabric plane separation
Question 114Question →

Match each HTTP request method used in network automation REST APIs to its corresponding CRUD operation and operational behavior.

Click a left item, then click its matching right item

Items

HTTP GET
HTTP POST
HTTP PUT
HTTP PATCH
HTTP DELETE

Matches

Show answer & explanation

Answer

HTTP GET matches Read (safe/idempotent data retrieval); HTTP POST matches Create (non-idempotent resource creation); HTTP PUT matches Update (idempotent full replacement); HTTP PATCH matches Update (partial field modification); HTTP DELETE matches Delete (resource removal).
In RESTful web services, HTTP verbs map directly to CRUD operations: GET to Read (retrieves resources without side effects), POST to Create (adds a new sub-resource), PUT to Update (replaces an entire resource), PATCH to Update (modifies selected fields), and DELETE to Delete (removes a resource).

Step-by-Step Solution

1
Identify the basic CRUD operations for retrieving and removing data.
HTTP GET performs the Read operation without altering server state, while HTTP DELETE performs the Delete operation to remove a resource.
GET and DELETE are standard operations for viewing and removing targeted API resources.
2
Determine the resource creation method.
HTTP POST maps to Create and is non-idempotent because executing it multiple times creates multiple distinct items.
POST submits data to be processed by a parent resource.
3
Distinguish between the two update methods (PUT vs. PATCH).
HTTP PUT performs a full resource replacement, while HTTP PATCH performs a partial update.
PUT replaces the complete payload representation at the target URI, whereas PATCH modifies only the specified parameters inside the existing resource.

Key Concept

RESTful HTTP Verbs and CRUD Mapping
Estimated Time:1m 30s
Question 115Question →

A network engineer is auditing a enterprise Software-Defined Access (SD-Access) fabric deployment where endpoint devices in different subnets communicate across the campus network. During a traffic flow analysis, the engineer notes that Layer 2 Ethernet frames are encapsulated into VXLAN packets at the edge switches before transport. Which function represents the primary operational responsibility of the underlying network (underlay) in this architecture?

Show answer & explanation

Answer: Providing IP reachability and routing between physical fabric nodes and Tunnel Endpoints (VTEPs)

Answer

The primary operational responsibility of the underlay network is providing IP reachability and routing between physical fabric nodes and Tunnel Endpoints (VTEPs).
The underlay network provides the physical infrastructure and Layer 3 unicast routing (using protocols such as IS-IS or OSPF) to establish reliable IP reachability between physical fabric devices and VTEP/RLOC interfaces.

Step-by-Step Solution

1
Define the role of the Underlay network in Software-Defined Architectures
The underlay is the physical infrastructure (switches, routers, links) and Layer 3 routing protocols (e.g., OSPF, IS-IS, BGP) that supply IP connectivity.
Without underlay IP reachability, overlay tunnels cannot be established between endpoints.
2
Differentiate Underlay transport from Overlay encapsulation and control functions
Overlay handles VXLAN encapsulation, LISP EID-to-RLOC mappings, and virtual network segmentations. The underlay only routes standard IP packets between the VTEP/RLOC loopback addresses.
Clear separation between underlay transport and overlay virtual networks is a fundamental SDN concept.

Key Concept

Underlay vs. Overlay Responsibilities in SDN Fabrics
Question 116Question →

A network automation script needs to issue an API request to a Cisco DNA Center endpoint to configure a global SNMP server setting. The requirement specifies that the request must create the SNMP resource at a specific URI if it does not exist, or completely replace the existing SNMP configuration at that URI if it does exist. Additionally, the operation must be idempotent so that running the script multiple times with the same payload produces the exact same state without side effects. Which HTTP verb must the script use to perform this action?

Show answer & explanation

Answer: PUT

Answer

The HTTP PUT method should be used because it is an idempotent operation designed to create or completely replace a target resource at a specified URI.
HTTP PUT is used in RESTful APIs to create or completely replace a resource at a target URI. Because PUT is idempotent, submitting identical requests repeatedly will yield the exact same resource state on the target controller without creating duplicate objects.

Step-by-Step Solution

1
Identify the required operational characteristics
The operation must create or completely replace a resource representation at a specific URI and must be idempotent.
REST API architectural guidelines define specific HTTP verbs for different state mutation behaviors.
2
Evaluate the HTTP PUT verb properties
HTTP PUT maps to Create/Update in CRUD operations when acting on a specific URI, replacing existing data or creating it if absent, and is defined as idempotent.
Calling PUT multiple times with the exact same payload produces the same result on the target server state.
3
Distinguish PUT from POST and PATCH
POST is non-idempotent and creates subordinate resources, while PATCH applies partial updates to specific fields.
Only PUT satisfies both complete replacement/creation at a target URI and strict idempotency requirements.

Key Concept

HTTP Verbs and Idempotency in REST APIs
Question 117Question →

A network administrator is implementing a Cisco Software-Defined Access (SD-Access) architecture across an enterprise network campus. Which two operational characteristics are specific functions of the fabric overlay network rather than the underlay network? (Select two.)

Select all that apply

Show answer & explanation

Answer: Encapsulating user data traffic into VXLAN packets to maintain logical Layer 2 and Layer 3 virtual network boundaries across the fabric.; Maintaining a control plane mapping database using LISP to map endpoint identifiers to their current routing locator addresses.

Answer

The two correct overlay functions are encapsulating user data traffic into VXLAN packets to maintain logical network boundaries, and using LISP to map endpoint identifiers (EIDs) to routing locators (RLOCs).
In software-defined architectures (such as Cisco SD-Access), the overlay network creates logical virtual networks over the physical topology. The data plane uses VXLAN encapsulation to carry Layer 2 Ethernet frames and Layer 3 IP packets wrapped in UDP headers between fabric nodes. The control plane uses LISP (Locator/ID Separation Protocol) to manage the mapping database connecting Endpoint Identifiers (EIDs) to Routing Locators (RLOCs).

Step-by-Step Solution

1
Differentiate between the roles of underlay and overlay networks in an SDN fabric architecture.
The underlay provides physical interconnectivity and routing reachability between fabric nodes (RLOCs), while the overlay builds virtual networks on top of the underlay.
Clear layer separation is required to identify which protocols and mechanisms belong to the overlay layer.
2
Identify the data plane and control plane encapsulation mechanisms used by the SD-Access overlay.
VXLAN provides Layer 2 and Layer 3 overlay data plane encapsulation, and LISP provides overlay control plane location/identity separation mapping.
VXLAN and LISP are the defining overlay protocols in Cisco SD-Access.

Key Concept

Overlay vs. Underlay Roles in SDN Fabrics
Question 118Question →

A network administrator is designing an automation script that interacts with a REST-based API on a Cisco network controller. Which two statements accurately describe the behavior and characteristics of HTTP verbs in this REST API implementation? (Select two.)

Select all that apply

Show answer & explanation

Answer: HTTP POST operations create new resources under a target collection and are non-idempotent.; HTTP PUT operations completely replace an existing resource state or create a resource at a specific URI, making them idempotent.

Answer

The correct statements are that HTTP POST operations create new resources under a target collection and are non-idempotent, and HTTP PUT operations completely replace an existing resource state or create a resource at a specific URI, making them idempotent.
HTTP POST corresponds to creating resources in CRUD operations and is non-idempotent because duplicate calls produce multiple entities. HTTP PUT completely replaces a resource state or creates it at a designated URI, making it idempotent because repeating the request leaves the server in the identical state.

Step-by-Step Solution

1
Analyze HTTP POST characteristics.
POST creates new resources and is non-idempotent.
In RESTful architecture, POST creates child resources under a URI. Repeated POST requests produce multiple resources with unique identifiers.
2
Analyze HTTP PUT characteristics.
PUT completely replaces a resource and is idempotent.
PUT replaces the full target payload at a designated URI. Repeated execution produces the exact same resource state on the server.
3
Evaluate the incorrect options regarding GET and PATCH.
GET is read-only and safe, whereas PATCH performs partial updates.
GET never modifies server state, while PATCH applies partial updates rather than retrieving resource data.

Key Concept

RESTful API HTTP Verbs, CRUD Operations, and Idempotency
Question 119Question →

During the deployment of an enterprise Cisco Software-Defined Access (SD-Access) fabric, a network engineer must ensure that all fabric edge and control plane switches can exchange IP packets directly. Traditional Layer 3 routing protocols such as OSPF or IS-IS are configured across the physical switch interconnects to establish transport reachability for tunnel endpoints. Which architectural layer is defined by this underlying physical IP routing infrastructure?

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Answer: The underlay network

Answer

The underlay network
The underlay network consists of the physical routers, switches, and links operating traditional Layer 3 interior gateway protocols (such as IS-IS or OSPF). Its primary purpose in an SDN fabric architecture is to supply robust, highly available IP reachability between all fabric nodes (VTEPs/RLOCs) so that overlay tunnels can be established.

Step-by-Step Solution

1
Analyze the role of physical IP routing in software-defined network architectures.
Identify that physical switches and Layer 3 routing protocols establish basic IP connectivity between network devices.
Before virtual tunnels can form, physical devices must be able to reach each other via IP.
2
Differentiate between underlay, overlay, and control plane layers.
Confirm that the physical topology and routing protocol layer (OSPF/IS-IS/BGP) is called the underlay network.
The underlay provides the foundational IP transport upon which overlay encapsulation protocols (like VXLAN) operate.

Key Concept

Software-Defined Architecture: Underlay vs. Overlay
Question 120Question →

Associate each software-defined network component on the left with its primary architectural function within a Cisco enterprise campus fabric on the right.

Click a left item, then click its matching right item

Items

Underlay Network
VXLAN Header
LISP Map-Server / Map-Resolver
Fabric Edge Node

Matches

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Answer

Underlay Network matches physical L3 IP reachability provider; VXLAN Header matches VNI and group policy tag carrier; LISP Map-Server / Map-Resolver matches central database mapping EIDs to RLOCs; Fabric Edge Node matches onboarding end devices and operating as a VTEP.
Each software-defined component occupies a distinct layer: the Underlay Network handles physical Layer 3 routing between nodes; the VXLAN Header encapsulates data packets with Virtual Network Identifiers (VNIs); the LISP Map-Server/Map-Resolver functions as the control plane tracking host EIDs to switch RLOCs; and the Fabric Edge Node connects endpoints while acting as a VTEP.

Step-by-Step Solution

1
Identify Underlay Network role
Recognized that the underlay provides physical infrastructure connectivity using standard L3 routing protocols.
Overlay encapsulation requires basic underlying IP routing between transport nodes.
2
Identify VXLAN Header role
Recognized VXLAN as the data plane encapsulation mechanism carrying VNIs.
VXLAN encapsulates Layer 2 Ethernet frames inside UDP packets across the overlay.
3
Identify LISP Map-Server / Map-Resolver role
Recognized LISP as the control plane mapping protocol tracking host locations.
LISP decouples host identity (EID) from host location (RLOC) to eliminate ARP flooding.
4
Identify Fabric Edge Node role
Recognized Fabric Edge as the ingress/egress boundary device acting as a VTEP.
Edge nodes interface between traditional end-user endpoints and the fabric overlay.

Key Concept

Distinguishing roles across Underlay transport, VXLAN data plane encapsulation, LISP control plane mapping, and Fabric Edge VTEPs
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