Mixed Deck — All ACA Topics Flashcards

Which protocol dynamically assigns IP addresses, subnet masks, gateways, and DNS server information to hosts?

Answer: DHCP

DHCP (Dynamic Host Configuration Protocol) automatically provides hosts with IP addressing parameters, eliminating the need for manual static configuration.

What is the broadcast address for the subnet 192.168.10.64/26?

Answer: 192.168.10.127

The /26 subnet starting at 192.168.10.64 has a block size of 64; the broadcast address is 192.168.10.64 + 63 = 192.168.10.127.

What is the loopback address in IPv4, and what is it used for?

Answer: 127.0.0.1 – used to test the local TCP/IP stack without sending traffic on the network

The IPv4 loopback address 127.0.0.1 (range 127.0.0.0/8) routes traffic back to the local host, allowing software to test network stack functionality.

What is the purpose of IPSec tunnels in Aruba SD-WAN deployments?

Answer: To create encrypted overlays over public Internet WAN links, ensuring secure branch-to-branch or branch-to-HQ traffic

Aruba SD-WAN uses IPSec tunnels to encrypt traffic traversing public Internet connections, creating a secure overlay network that protects branch communications regardless of the underlying transport.

Which authentication framework is most commonly used for enterprise wireless networks to authenticate users against a RADIUS server?

Answer: 802.1X/EAP

802.1X with EAP (Extensible Authentication Protocol) is the standard enterprise authentication framework that integrates with RADIUS servers.

Aruba's 802.11ax (Wi-Fi 6) access points belong to which product series?

Answer: AP-500 series

The Aruba AP-500 series (e.g., AP-505, AP-515, AP-535) are Wi-Fi 6 (802.11ax) access points designed for high-density enterprise environments.

What is the recommended maximum retry count behavior when a wireless client fails to connect to an AP?

Answer: The client backs off using exponential backoff and retries up to a vendor-defined limit

Wi-Fi clients use binary exponential backoff to manage retransmissions, increasing the contention window with each failed attempt up to a maximum retry limit.

Which transmission mode allows data to flow in both directions simultaneously?

Answer: Full-duplex

Full-duplex allows simultaneous bidirectional communication, effectively doubling throughput compared to half-duplex on the same link.

What is the difference between a routing protocol and a routed protocol?

Answer: A routing protocol exchanges routing information between routers; a routed protocol is the protocol whose traffic is being routed

A routing protocol like OSPF exchanges topology information between routers, while a routed protocol like IPv4 is the actual payload being forwarded.

What is the primary advantage of Aruba's ClientMatch technology?

Answer: It steers clients to the best available AP based on real-time RF conditions

ClientMatch continuously monitors client signal quality and steers clients to the best-performing AP or radio band, solving sticky client issues without client-side changes.

What does Role-Based Access Control (RBAC) do?

Answer: Manages access based on user roles

Role-Based Access Control (RBAC) is a method of restricting network access based on the roles of individual users within an organization. Instead of assigning permissions directly to users, permissions are assigned to specific roles, and users are then assigned to those roles. This simplifies management and ensures users only have access to the resources necessary for their job functions.

What Aruba tool would you use to visualize the RF environment and identify coverage gaps?

Answer: Aruba Central RF Health or Aruba AirWave VisualRF

Aruba Central RF Health and AirWave VisualRF provide floor plan-based RF visualization to identify coverage gaps, interference, and channel planning issues.

What is the purpose of a default route (0.0.0.0/0) in routing?

Answer: To forward packets with no more-specific matching route, typically toward the internet gateway

A default route matches any destination with no more-specific route in the routing table and typically points traffic toward the internet or upstream router.

What type of interface does ArubaOS-CX's Network Analytics Engine (NAE) provide?

Answer: Python-based scripting for monitoring and automated remediation

The NAE in ArubaOS-CX allows network engineers to write Python scripts (called agents) that monitor network state and trigger automated actions when conditions are met.

What is the purpose of Aruba Instant Access Points (IAPs)?

Answer: To offer controller-less Wi-Fi access

Aruba Instant Access Points (IAPs) are designed to operate without a dedicated hardware controller. They form a virtual controller cluster, where one IAP acts as the primary controller, simplifying deployment and management for smaller to medium-sized networks. This 'controller-less' architecture reduces complexity and cost compared to traditional controller-based solutions.

Which protocol dynamically negotiates link aggregation between Aruba switches?

Answer: LACP

LACP (Link Aggregation Control Protocol) is the IEEE 802.3ad standard that dynamically negotiates and manages link aggregation groups.

What is the purpose of SSID tunneling back to a mobility controller?

Answer: To centralize traffic forwarding and policy enforcement at the controller for a specific SSID

SSID tunneling sends client traffic through a GRE tunnel back to the controller where centralized policies, firewalling, and forwarding are applied.

Which layer of the OSI model is responsible for end-to-end communication?

Answer: Transport

The Transport Layer (Layer 4) of the OSI model is responsible for end-to-end communication between applications on different hosts. It ensures reliable data transfer through services like segmentation, reassembly, error checking, and flow control. Protocols like TCP and UDP operate at this layer to manage the delivery of data from a source application to a destination application, guaranteeing data integrity and order.

What is the purpose of ECMP (Equal-Cost Multi-Path) routing?

Answer: To load-balance traffic across multiple paths with equal routing metrics

ECMP allows a router to load-balance traffic across multiple equal-cost paths simultaneously, increasing throughput and redundancy.

In Aruba's SD-Branch solution, what replaces the traditional branch router and controller?

Answer: Aruba SD-WAN gateway

Aruba SD-Branch uses SD-WAN gateways to consolidate routing, security, and network services at the branch, replacing traditional hardware.