Important HPE6-A85 Exam Questions

Answer: A

Explanation:

The part of WPA Key Hierarchy that is used to encrypt and/or decrypt data is Pairwise Temporal Key (PTK). PTK is a key that is derived from PMK Pairwise Master Key (PMK) is a key that is derived from PSK Pre-shared Key (PSK) is a key that is shared between two parties before communication begins , ANonce Authenticator Nonce (ANonce) is a random number generated by an authenticator (a device that controls access to network resources, such as an AP) , SNonce Supplicant Nonce (SNonce) is a random number generated by supplicant (a device that wants to access network resources, such as an STA) , AA Authenticator Address (AA) is MAC address of authenticator , SA Supplicant Address (SA) is MAC address of supplicant using Pseudo-Random Function (PRF). PTK consists of four subkeys:

KCK Key Confirmation Key (KCK) is used for message integrity check

KEK Key Encryption Key (KEK) is used for encryption key distribution

TK Temporal Key (TK) is used for data encryption

MIC Message Integrity Code (MIC) key

The subkey that is specifically used for data encryption is TK Temporal Key (TK). TK is also known as Pairwise Transient Key (PTK). TK changes periodically during communication based on time or number of packets transmitted.

The other options are not part of WPA Key Hierarchy because:

PMK: PMK is not part of WPA Key Hierarchy, but rather an input for deriving PTK.

KCK: KCK is part of WPA Key Hierarchy, but it is not used for data encryption, but rather for message integrity check.

Nonce: Nonce is not part of WPA Key Hierarchy, but rather an input for deriving PTK.

Answer: B

Explanation:

When generating a Multiple Pre-Shared Key (MPSK) for headless devices using the ClearPass self-service registration page, the MAC address of the device is required. MPSK associates a unique PSK with the MAC address of a device, providing a way to authenticate devices that may not have a user interface.

Answer: B

Explanation:

The main characteristic of the 6 GHz band that is true among the given options is that in North America, the 6 GHz band offers more 80 MHz channels than there are 40 MHz channels in the 5 GHz band. This characteristic provides more spectrum availability, less interference, and higher throughput for wireless devices that support Wi-Fi 6E Wi-Fi Enhanced (Wi-Fi 6E) is an extension of Wi-Fi 6 (802.11ax) standard that operates in the newly available unlicensed frequency spectrum around 6 GHz in addition to existing bands below it. Some facts about this characteristic are:

In North America, there are up to seven non-overlapping channels available in each of three channel widths (20 MHz, 40 MHz, and 80 MHz) in the entire unlicensed portion of the new spectrum (5925--7125 MHz). This means there are up to 21 non-overlapping channels available for Wi-Fi devices in total.

In comparison, in North America, there are only nine non-overlapping channels available in each of two channel widths (20 MHz and 40 MHz) in the entire unlicensed portion of the existing spectrum below it (2400--2483 MHz and 5150--5825 MHz). This means there are only up to nine non-overlapping channels available for Wi-Fi devices in total.

Therefore, in North America, there are more than twice as many non-overlapping channels available in each channel width in the new spectrum than in the existing spectrum below it.

Specifically, there are more than twice as many non-overlapping channels available at 80 MHz width (seven) than at 40 MHz width (three) in the existing spectrum below it.

The other options are not true because:

Less RF signal is absorbed by objects in a 6 GHz WLAN: This option is false because higher frequency signals tend to be more absorbed by objects than lower frequency signals due to higher attenuation Attenuation is a general term that refers to any reduction in signal strength during transmission over distance or through an object or medium . Therefore, RF signals in a 6 GHz WLAN would be more absorbed by objects than RF signals in a lower frequency WLAN.

The 6 GHz band is fully backward compatible with existing bands: This option is false because Wi-Fi devices need to support Wi-Fi 6E standard to operate in the new spectrum around 6 GHz . Existing Wi-Fi devices that do not support Wi-Fi 6E standard cannot use this spectrum and can only operate in existing bands below it.

Low Power Devices are allowed for indoor and outdoor usage: This option is false because Low Power Indoor Devices (LPI) are only allowed for indoor usage under certain power limits and registration requirements . Outdoor usage of LPI devices is prohibited by regulatory authorities such as FCC Federal Communications Commission (FCC) is an independent agency of United States government that regulates communications by radio, television, wire, satellite, and cable across United States . However, outdoor usage of Very Low Power Devices (VLP) may be allowed under certain power limits and without registration requirements.

Answer: B

Explanation:

Virtual Router Redundancy Protocol (VRRP) is a network protocol that provides automatic assignment of available Internet Protocol (IP) routers to participating hosts. VRRP sends its messages over multicast for communication among routers for the election process of the master and advertisement of the virtual IP address.

Answer: C

Explanation:

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. Reference:1https://en.wikipedia.org/wiki/Signal-to-noise_ratio2https://documentation.meraki.com/MR/Wi-Fi_Basics_and_Best_Practices/Signal-to-Noise_Ratio_%28SNR%29_and_Wireless_Signal_Strength