HPE6-A85 Aruba Certified Campus Access Associate Exam Questions and Answers

OSPF Open Shortest Path First. OSPF is a link-state routing protocol that uses a hierarchical structure to create a routing topology for IP networks. OSPF routers exchange routing information with their neighbors using Hello packets, which are sent periodically on each interface. To establish an adjacency Adjacency is a relationship formed between selected neighboring routers for the purpose of exchanging routing information., OSPF routers must agree on several parameters, including Hello timers, which specify how often Hello packets are sent on an interface. If the Hello timers do not match between neighboring routers, they will not form an adjacency and will not exchange routes. References:https://www.arubanetworks.com/techdocs/ArubaOS_86_Web_Help/Content/arubaos-solutions/osfp/osfp.htm

The command that is used to set a default route to 10.4.5.1 on an Aruba CX switch when in-band management using an SVI is being used is ip route 0.0 0 0/0 10.4.5.1 . This command specifies the destination network address (0.0 0 0) and prefix length (/0) and the next-hop address (10.4.5.1) for reaching any network that is not directly connected to the switch. The default route applies to the default VRF Virtual Routing and Forwarding. VRF is a technology that allows multiple instances of a routing table to co-exist within the same router at the same time. VRFs are typically used to segment network traffic for security, privacy, or administrative purposes. , which is used for in-band management traffic that goes through an SVI Switch Virtual Interface. SVI is a virtual interface on a switch that allows the switch to route packets between different VLANs on the same switch or different switches that are connected by a trunk link. An SVI is associated with a VLAN and has an IP address and subnet mask assigned to it12. References: 1 https://www.arubanetworks.com/techdocs/AOS-CX/10_08/HTML/ip_route_4100i-6000-6100-6200/Content/Chp_StatRoute/def-rou.htm  2 https://www.arubanetworks.com/techdocs/AOS-CX/10_08/HTML/ip_route_4100i-6000-6100-6200/Content/Chp_VRF/vrf-overview.htm

LACP is a protocol that allows multiple physical links to be aggregated into a single logical link for increased bandwidth and redundancy. LACP must be configured on both ends of the link for it to work properly. In this case, EDGE1 has LACP configured on its uplink port-channel 1, but CORE1 does not have LACP configured on its corresponding port-channel 1. This causes a mismatch and prevents the link from coming up. References:https://www.arubanetworks.com/techdocs/ArubaOS_86_Web_Help/Content/arubaos-solutions/1-overview/lacp.htm

The option that fulfills the requirements is to create individual SSIDs with unique PSK for each loT class, using 2.4 GHz and 5 GHz band. This option provides the following benefits:

• Each loT class has a unique PSK that can be used to apply a different security policy as a role. This enhances the security and flexibility of the WLAN network.
• Individual SSIDs allow for better isolation and management of different loT classes. This improves the performance and scalability of the WLAN network.
• Using both 2.4 GHz and 5 GHz bands allows for backward compatibility with loT devices that operate only with 802.11b, which uses the 2.4 GHz band1. It also allows for higher throughput and less interference for loT devices that support 802.11a, 802.11g, 802.11n, or 802.11ac, which use the 5 GHz band2.

The other options do not fulfill the requirements because:

• Single SSID with MPSK for each loT class using 5 GHz and 6 GHz bands: This option does not support loT devices that operate only with 802.11b, which uses the 2.4 GHz band1. It also does not optimize the performance of the WLAN network, as a single SSID may cause co-channel interference and congestion among different loT classes.
• Single SSID with MPSK for each loT class using 2.4 GHz and 5 GHz bands: This option does not optimize the performance of the WLAN network, as a single SSID may cause co-channel interference and congestion among different loT classes.
• Individual SSIDs with unique PSK for each loT class, using 5 GHz and 6 GHz bands: This option does not support loT devices that operate only with 802.11b, which uses the 2.4 GHz band1.

References: 1 https://en.wikipedia.org/wiki/IEEE_802.11b-1999  2 https://www.lifewire.com/wireless-standards-802-11a-802-11b-g-n-and-802-11ac-816553

The source that WPA3-Personal uses to generate a different Pairwise Master Key (PMK) each time a station connects to the wireless network is session-specific information (MACs and nonces). WPA3-Personal uses Simultaneous Authentication of Equals (SAE) to replace PSK authentication in WPA2-Personal. SAE is a secure key establishment protocol that uses a Diffie-Hellman key exchange to derive a shared secret between two parties without revealing it to an eavesdropper. SAE involves the following steps:

• The station and the access point exchange Commit messages that contain their MAC addresses and random numbers called nonces.
• The station and the access point use their own passwords and the received MAC addresses and nonces to calculate a shared secret called SAE Password Element (PE).
• The station and the access point use their own PE and the received MAC addresses and nonces to calculate a shared secret called SAE Key Seed (KS).
• The station and the access point use their own KS and the received MAC addresses and nonces to calculate a shared secret called SAE Key Confirmation Key (KCK).
• The station and the access point use their own KCK and the received MAC addresses and nonces to calculate a confirmation value called SAE Confirm.
• The station and the access point exchange Confirm messages that contain their SAE Confirm values.
• The station and the access point verify that the received SAE Confirm values match their own calculated values. If they match, the authentication is successful and the station and the access point have established a shared secret called SAE PMK.

The SAE PMK is different for each session because it depends on the MAC addresses and nonces that are exchanged in each authentication process. The SAE PMK is used as an input for the 4-way handshake that generates the Pairwise Temporal Key (PTK) for encrypting data frames.

The other options are not sources that WPA3-Personal uses to generate a different PMK each time a station connects to the wireless network because:

• Opportunistic Wireless Encryption (OWE): OWE is a feature that provides encryption for open networks without requiring authentication or passwords. OWE uses a similar key establishment protocol as SAE, but it does not generate a PMK. Instead, it generates a Pairwise Secret (PS) that is used as an input for the 4-way handshake that generates the PTK.
• Simultaneous Authentication of Equals (SAE): SAE is not a source, but a protocol that uses session-specific information as a source to generate a different PMK each time a station connects to the wireless network.
• Key Encryption Key (KEK): KEK is not a source, but an output of the 4-way handshake that generates the PTK. KEK is used to encrypt group keys that are distributed by the access point.

References: https://www.wi-fi.org/discover-wi-fi/wi-fi-certified-6e https://www.wi-fi.org/file/wi-fi-alliance-unlicensed-spectrum-in-the-us https://www.cisco.com/c/en/us/products/collateral/wireless/catalyst-9100ax-access-points/wpa3-dep-guide-og.html https://info.support.huawei.com/info-finder/encyclopedia/en/WPA3.html https://rp.os3.nl/2019-2020/p99/presentation.pdf

USE CASE: a) Controls the dynamic addition and removal of ports to groups Technology: 3) LACP

USE CASE: b) Tags Ethernet frames with an additional VLAN header Technology: 1) 802.1Q

USE CASE: c) Used to authenticate EAP-Capable client on a switch port Technology: 2) 802.1X

USE CASE: d) Used to identify a voice VLAN to an IP phone Technology: 4) LLDP

The following table summarizes the switching technologies and their use cases:

Technology

Use case

1) 802.1Q

802.1Q is a standard that defines how to create and manage virtual LANs (VLANs) on a network. VLANs allow network administrators to logically segment a network into different broadcast domains, improving security, performance, and manageability. 802.1Q tags Ethernet frames with an additional VLAN header that contains a VLAN identifier (VID), which indicates which VLAN the frame belongs to1.

2) 802.1X

802.1X is a standard that defines how to provide port-based network access control (PNAC) on a network. PNAC allows network administrators to authenticate and authorize devices before granting them access to network resources. 802.1X uses the Extensible Authentication Protocol (EAP) to exchange authentication messages between a supplicant (a device that wants to access the network), an authenticator (a device that controls access to the network, such as a switch), and an authentication server (a device that verifies the credentials of the supplicant, such as a RADIUS server)2.

3) LACP

LACP stands for Link Aggregation Control Protocol, which is part of the IEEE 802.3ad standard that defines how to bundle multiple physical links into a single logical link, also known as a link aggregation group (LAG) or an EtherChannel. LAGs provide increased bandwidth, load balancing, and redundancy for network connections. LACP controls the dynamic addition and removal of ports to groups, ensuring that only ports with compatible configurations can form a LAG3.

4) LLDP

LLDP stands for Link Layer Discovery Protocol, which is part of the IEEE 802.1AB standard that defines how to discover and advertise information about neighboring devices on a network. LLDP operates at Layer 2 of the OSI model and uses TLVs (type-length-value) to exchange information such as device name, port number, VLAN ID, capabilities, and power requirements. LLDP can be used to identify a voice VLAN to an IP phone by sending a TLV that contains the voice VLAN ID and priority.

References: 1 https://en.wikipedia.org/wiki/IEEE_802.1Q  2 https://en.wikipedia.org/wiki/IEEE_802.1X  3 https://en.wikipedia.org/wiki/Link_aggregation https://en.wikipedia.org/wiki/Link_Layer_Discovery_Protocol

The best technology to use for dropping excessive broadcast traffic on ingress to an ArubaOS-CX switch is rate limiting. Rate limiting is a feature that allows network administrators to control the amount of traffic that enters or leaves a port or a VLAN on a switch by setting bandwidth thresholds or limits. Rate limiting can be used to prevent network congestion, improve network performance, enforce service level agreements(SLAs), or mitigate denial-of-service (DoS) attacks. Rate limiting can be applied to broadcast traffic on ingress to an ArubaOS-CX switch by using the storm-control command in interface configuration mode. This command allows network administrators to specify the percentage of bandwidth or packets per second that can be used by broadcast traffic on an ingress port. If the broadcast traffic exceeds the specified threshold, the switch will drop the excess packets.

The other options are not technologies for dropping excessive broadcast traffic on ingress because:

• DWRR queuing: DWRR stands for Deficit Weighted Round Robin, which is a queuing algorithm that assigns different weights or priorities to different traffic classes or queues on an egress port. DWRR ensures that each queue gets its fair share of bandwidth based on its weight while avoiding starvation of lower priority queues. DWRR does not drop excessive broadcast traffic on ingress, but rather schedules outgoing traffic on egress.
• QoS shaping: QoS stands for Quality of Service, which is a set of techniques that manage network resources and provide different levels of service to different types of traffic based on their requirements. QoS shaping is a technique that delays or buffers outgoing traffic on an egress port to match the available bandwidth or rate limit. QoS shaping does not drop excessive broadcast traffic on ingress, but rather smooths outgoing traffic on egress.
• Strict queuing: Strict queuing is another queuing algorithm that assigns different priorities to different traffic classes or queues on an egress port. Strict queuing ensures that higher priority queues are always served before lower priority queues regardless of their bandwidth requirements or weights. Strict queuing does not drop excessive broadcast traffic on ingress, but rather schedules outgoing traffic on egress.

References: https://en.wikipedia.org/wiki/Rate_limiting https://www.arubanetworks.com/techdocs/AOS-CX_10_08/NOSCG/Content/cx-noscg/qos/storm-control.htm https://www.arubanetworks.com/techdocs/AOS-CX_10_08/NOSCG/Content/cx-noscg/qos/dwrr.htm https://www.arubanetworks.com/techdocs/AOS-CX_10_08/NOSCG/Content/cx-noscg/qos/shaping.htm https://www.arubanetworks.com/techdocs/AOS-CX_10_08/NOSCG/Content/cx-noscg/qos/strict.htm

dBm is a unit of power that measures the ratio of a given power level to 1 mW. The formula to convert dBm to mW is: P(mW) = 1mW * 10^(P(dBm)/10). Therefore, -20 dBm corresponds to 0.01 mW, as follows: P(mW) = 1mW * 10^(-20/10) = 0.01 mW References:https://www.rapidtables.com/convert/power/dBm_to_mW.html

The RADIUS message that you should look for to ensure a successful connection via 802.1X is Access-Accept. This message indicates that the RADIUS server has authenticated and authorized the supplicant (the device that wants to access thenetwork) and has granted it access to the network resources. The Access-Accept message may also contain additional attributes such as VLAN ID, session timeout, or filter ID that specify how the authenticator (the device that controls access to the network, such as a switch) should treat the supplicant’s traffic.

The other options are not RADIUS messages because:

• Authorized: This is not a RADIUS message, but a state that indicates that a port on an authenticator is allowed to pass traffic from a supplicant after successful authentication and authorization.
• Success: This is not a RADIUS message, but a status that indicates that an EAP Extensible Authentication Protocol (EAP) is an authentication framework that provides support for multiple authentication methods, such as passwords, certificates, tokens, or biometrics. EAP is used in wireless networks and point-to-point connections to provide secure authentication between a supplicant (a device that wants to access the network) and an authentication server (a device that verifies the credentials of the supplicant). exchange has completed successfully between a supplicant and an authentication server.
• Authenticated: This is not a RADIUS message, but a state that indicates that a port on an authenticator has received an EAP-Success message from an authentication server after successful authentication of a supplicant.

References: https://en.wikipedia.org/wiki/RADIUS#Access-Accept https://www.cisco.com/c/en/us/support/docs/security-vpn/remote-authentication-dial-user-service-radius/13838-10.html https://en.wikipedia.org/wiki/IEEE_802.1X#Port-based_network_access_control https://en.wikipedia.org/wiki/Extensible_Authentication_Protocol#EAP_exchange

QoS Quality of Service (QoS) is a set of techniques that manage network resources and provide different levels of service to different types of traffic based on their requirements. QoS can improve network performance, reduce latency, increase throughput, and prevent congestion. concept and its definition. Here is my answer:

QoS Concept:

• Best Effort Service
• Class of Service
• Differentiated Services
• WMM ====================== Definition:

d) A method where traffic is treated equally in a first-come, first-served manner a) A method for classifying network traffic at Layer 2 by marking 802.1Q VLAN Ethernet frames with one of eight service classes b) A method for classifying network traffic at Layer 3 by marking packets with one of 64 different service classes c) A method for classifying network traffic using access categories based on the IEEE 802.11e QoS standard

Short But Comprehensive Explanation of Correct Answer Only: The correct match between QoS concept and its definition is as follows:

• Best Effort Service: This is a method where traffic is treated equally in a first-come, first-served manner without any prioritization or differentiation. This is the default service level for most networks and applications that do not have specific QoS requirements or guarantees. Best Effort Service does not provide any assurance of bandwidth, delay, jitter, or packet loss.
• Class of Service: This is a method for classifying network traffic at Layer 2 by marking 802.1Q VLAN Ethernet frames with one of eight service classes (0 to 7). These service classes are also known as IEEE 802.1p priority values or PCP Priority Code Point (PCP) is a 3-bit field in the 802.1Q VLAN tag that indicates the priority level of an Ethernet frame . Class of Service allows network devices to identify and handle different types of traffic based on their priority levels. Class of Service is typically used in LAN Local Area Network (LAN) is a network that connects devices within a limited geographic area, such as a home, office, or building environments where Layer 2 switching is predominant.
• Differentiated Services: This is a method for classifying network traffic at Layer 3 by marking packets with one of 64 different service classes (0 to 63). These service classes are also known as DiffServ Code Points (DSCP) DiffServ Code Point (DSCP) is a 6-bit field in the IP header that indicates the service class of a packet . Differentiated Services allows network devices to identify and handle different types of traffic based on their service classes. Differentiated Services is typically used in WAN Wide Area Network (WAN) is a network that connects devices across a large geographic area, such as a country or continent environments where Layer 3 routing is predominant.
• WMM: This is a method for classifying network traffic using access categories based on the IEEE 802.11e QoS standard. WMM stands for Wi-Fi Multimedia and it is a certification program developed by the Wi-Fi Alliance to enhance QoS for wireless networks. WMM defines four access categories (AC): Voice, Video, Best Effort, and Background. These access categories correspond to different priority levels and contention parameters for wireless traffic. WMM allows wireless devices to identify and handle different types of traffic based on their access categories.

References: https://en.wikipedia.org/wiki/Quality_of_service https://www.cisco.com/c/en/us/td/docs/ios-xml/ios/qos_dfsrv/configuration/xe-16/qos-dfsrv-xe-16-book/qos-dfsrv-overview.html https://www.cisco.com/c/en/us/support/docs/quality-of-service-qos/qos-packet-marking/10103-dscpvalues.html https://www.cisco.com/c/en/us/support/docs/wireless-mobility/wireless-lan-wlan/81831-qos-wlan.html https://www.wi-fi.org/discover-wi-fi/wi-fi-certified-wmm

Signal to noise ratio (SNR) is a measure that compares the level of a desired signal to the level of background noise. SNR is defined as the ratio of signal power to the noise power, often expressed in decibels (dB). A high SNR means that the signal is clear and easy to detect or interpret, while a low SNR means that the signal is corrupted or obscured by noise and may be difficult to distinguish or recover1. When the signal from an AP Access Point. AP is a device that allows wireless devices to connect to a wired network using Wi-Fi, or related standards. weakens by being absorbed as it moves through an object, such as a wall or a furniture, the signal power decreases. This reduces the SNR and affects the quality of the wireless connection. The noise power may also increase due to interference from other sources, such as other APs or devices operating in the same frequency band2. Therefore, the correct answer is that SNR decreases when the signal from an AP weakens by being absorbed as it moves through an object. References: 1 https://en.wikipedia.org/wiki/Signal-to-noise_ratio  2 https://documentation.meraki.com/MR/Wi-Fi_Basics_and_Best_Practices/Signal-to-Noise_Ratio_%28SNR%29_and_Wireless_Signal_Strength

 Virtual Switching Extension (VSX) is a feature that allows two Aruba CX switches to operate as a single logical device with a single control plane and data plane. VSX provides high availability, scalability, and simplified management for campus and data center networks3. In VSX, one switch is designated as the primary switch and the other as the secondary switch. The primary switch owns and responds to ARP Address Resolution Protocol. ARP is a communication protocol used for discovering the link layer address, such as a MAC address, associated with a given internet layer address, typically an IPv4 address. This mapping is a critical function in the Internet protocol suite. requests for the virtual IP address of the VSX pair4. The virtual IP address is used as the default gateway for clients connected to the access switch. If the primary switch fails, the secondary switch takes over the virtual IP address and continues to forward traffic for the clients5. References: 3 https://www.arubanetworks.com/techdocs/AOS-CX_10_04/UG/Content/cx-ug/vsx/vsx-overview.htm  4 https://www.arubanetworks.com/techdocs/AOS-CX_10_04/UG/Content/cx-ug/vsx/vsx-ip-addressing.htm  5 https://www.arubanetworks.com/techdocs/AOS-CX_10_04/UG/Content/cx-ug/vsx/vsx-failover.htm

Manual provisioning is a method to add switches to Aruba Central without using DHCP or DNS. It requires the user to enter the switch serial number, MAC address, and activation code in Aruba Central, and then configure the switch with the same activation code and Aruba Central’s IP address. References:https://help.central.arubanetworks.com/latest/documentation/online_help/content/devices/switches/provisioning/manual-provisioning.htm