DevNet Associate flashcards

32 cards. Read the term and the definition here. The deck at the top of this page is optional.

Git three-stage workflow

Files move from the working directory to the staging area with git add, into the local repository with git commit, and to a remote with git push; each stage is a separate snapshot boundary.

Git fast-forward merge

When the target branch has received no new commits since the feature branch diverged, Git simply moves the branch pointer forward and no merge commit is created.

JSON data format

A text format of key-value objects and ordered arrays using double-quoted strings, numbers, booleans, and null; objects use braces and arrays use brackets, with no comments allowed.

YAML indentation rules

YAML structures data using spaces rather than tabs; indentation defines nesting, list items start with a dash, and key-value pairs use a colon followed by a space.

Model-View-Controller pattern

Model-View-Controller separates data and business logic in the model, presentation in the view, and input handling in the controller, so each layer can change independently.

Unit versus integration tests

A unit test exercises one function or class in isolation with mocked dependencies; an integration test verifies that multiple components, services, or APIs work together correctly.

Idempotent HTTP methods

GET, PUT, DELETE, and HEAD are idempotent: repeating the identical request leaves the server in the same state. POST is not idempotent because each call usually creates a new resource.

HTTP 401 versus 403

A 401 Unauthorized response means the request lacks valid authentication credentials, while a 403 Forbidden response means the client is authenticated but lacks permission for that resource.

HTTP 429 Too Many Requests

This status indicates the client exceeded a rate limit; the response often carries a Retry-After header stating how long to wait before sending another request.

PUT versus PATCH

PUT replaces the entire resource representation with the supplied payload, while PATCH applies a partial modification containing only the fields that need to change.

OAuth client credentials flow

A machine-to-machine flow where the client application sends its own client ID and secret to the authorization server and receives an access token, with no end user involved.

Webhook callback

A server-to-server callback in which the provider sends an HTTP POST to a URL you registered when an event occurs, removing the need for your client to poll repeatedly.

API pagination

Large result sets are split into pages using parameters such as limit and offset, or cursor links returned in the response, so clients retrieve results incrementally rather than all at once.

Meraki API key header

Meraki Dashboard API calls are HTTPS requests carrying the header X-Cisco-Meraki-API-Key; the platform permits roughly five requests per second per organization.

DNA Center auth token

Cisco DNA Center (Catalyst Center) issues an X-Auth-Token from POST /dna/system/api/v1/auth/token using HTTP Basic credentials; that token accompanies later Intent API calls.

APIC aaaLogin cookie

ACI's APIC REST API authenticates by posting credentials to /api/aaaLogin.xml, which returns an APIC-cookie session token that must be included with subsequent requests.

NETCONF port 830

NETCONF runs over SSH on TCP port 830 and exchanges XML-encoded RPCs such as get-config, edit-config, and commit to read and modify device configuration.

YANG data model

A modeling language that defines the hierarchy, data types, and constraints of configuration and state data exposed by NETCONF or RESTCONF on a network device.

Container versus virtual machine

A container shares the host operating system kernel and packages only the application and its libraries; a virtual machine includes a full guest OS, making it heavier and slower to boot.

Blue-green deployment

Two identical environments run side by side; the new version is deployed to the idle environment, tested, then traffic switches over, allowing an instant rollback to the previous version.

Canary deployment

A new release is exposed to a small subset of users or traffic first; if metrics remain healthy the rollout expands gradually, limiting the impact of a faulty version.

12-factor configuration

Configuration that varies between deployments, such as credentials, endpoints, and feature flags, is stored in environment variables rather than code, keeping one build artifact across environments.

Secrets in Git history

API keys and passwords committed to Git remain recoverable in history even after deletion; they belong in a secret manager or environment variables, and any exposed credential must be rotated.

Ansible agentless model

Ansible pushes modules over SSH or WinRM from a control node to managed hosts; no agent is installed, and YAML playbooks run against hosts listed in an inventory.

Terraform state file

Terraform records the resources it manages in a state file, compares that state to the declarative configuration during plan, and applies only the resulting differences.

Configuration drift

The difference between the intended device or infrastructure configuration and what is actually running, caused by manual changes, failed automation, or out-of-band updates.

GitOps

An operating model where the desired infrastructure and application state lives in a Git repository, and an automated controller continuously reconciles live systems to match it.

Private IPv4 ranges

RFC 1918 private space is 10.0.0.0/8, 172.16.0.0/12, and 192.168.0.0/16; these addresses are not routed on the public internet and need NAT for external access.

TCP three-way handshake

The client sends a SYN, the server replies with SYN-ACK, and the client answers with ACK, synchronizing sequence numbers and establishing a reliable connection before data transfer.

ARP

Address Resolution Protocol broadcasts a request asking which MAC address owns a given IPv4 address in the local subnet, then caches the reply in the ARP table.

802.1Q VLAN tag

IEEE 802.1Q inserts a four-byte tag into the Ethernet frame containing a 12-bit VLAN ID, allowing one trunk link to carry traffic for multiple VLANs.

DNS A record

A DNS record mapping a hostname to an IPv4 address; AAAA maps to IPv6, CNAME creates an alias, and MX identifies mail servers for a domain.