Comptia Net+ - Module 6

What is the range of frequency bands for the wireless spectrum?

Spans frequency bands between 9 kHz and 300 GHz

What is ZigBee, and what is it designed for?

• A low-powered, battery-conserving wireless technology

• Designed to handle small amounts of data

What are some IoT devices ZigBee is used in?

Building automation, HVAC control, AMR (Automatic Meter Reading), and fleet management

What is Z-wave, and the 2 types of functions?

• a smart home protocol that provides two types of functions:

  • Signaling to manage connections

  • Control to transmit data and commands

What does a Z-Wave network controller (called a hub) do?

Receives commands from a smartphone or computer and relays the commands to various smart devices

Give 3 characteristics of bluetooth.

• Operates in the radio band of 2.4 GHz

• Hops between frequencies within band to reduce interference

• Requires close proximity

Give 2 attacks bluetooth is susceptible to

• Bluejacking—Send unsolicited data

• Bluesnarfing—Download data without permission

What is ANT+ based on and what does it gather?

• ANT+ technology based on ANT protocol:

  • Ad-hoc wireless protocol operating at 2.4 GHz

• ANT+ gathers information from sensors embedded in heart rate monitors, GPS devices, and activity monitoring devices

What does RFID (radio frequency identification) use?

Uses electromagnetic fields to store data on chip (RFID tag)

• Includes an antenna that can transmit and receive, and possibly a battery

What are 3 types of tag and reader combinations?

• ARPT (Active Reader Passive Tag)

• PRAT (Passive Reader Active Tag)

• ARAT (Active Reader Active Tag)

2 ways RFID is used in?

• Commonly used for inventory management

• “contactless” payment in a credit card

What is NFC (near-field communication) and how is the signal transmitted?

• A form of RFID that transfers data wirelessly over short distances

• Signal can be transmitted one way

What is IR (infrared) used for?

• Used primarily to collect data through various sensors

• Used to collect information such as:

  • Presence or level of liquid

  • Variations in blood flow

  • Proximity to the device

  • Commands from a control device

What is the difference between unidirectional and omnidirectional antennas?

• Unidirectional (directional antenna)

  • Wireless signals along single direction

• Omnidirectional antenna

  • Wireless signals with equal strength, clarity in all directions

What is propagation?

The way in which a wave travels from one point to another

What is LOS (line of sight)

Signal travels in straight line from transmitter to receiver

When obstacles are in a signal’s way, what are 6 things the signal may do?

• Pass through

• Be absorbed

• Fade

• Interfered by other noise

• Weaken (Attenuation)

• Follow different paths

What does excessive fading cause?

Excessive fading causes dropped connections or slow transmission

2 ways to correct signal attenuation?

• Repeat the signal (range extender)

• Increase the power

What is Signal-to-noise ratio (SNR)?

proportion of noise to the strength of a signal

What is 1 advantage and disadvantage of mutilpath signals?

• Advantage

  • Better chance of reaching destination

• Disadvantage

  • Signal delay will result in data errors

What are things that can be on the HAN (home area network)?

• IoT

• personal monitoring devices

• smart home devices

2 Examples of WPAN (wireless personal area network)

• Bluetooth

• ZigBee

What is the Max distance for PAN’s (personal area networks)?

PANs rarely exceed 10 meters in any direction

What are 6 wireless protocols that are created by IEEE’s 802.11 committee?

802.11b, 802.11a, 802.11g, 802.11n, 802.11ac, and 802.11ax

What is MIMO (multiple input-multiple output)?

Multiple access point and client device antennas may issue signal to one or more receivers

What is MU-MIMO (multiuser MIMO)?

Newer technology that allows multiple antennas to service multiple clients simultaneously

• Available with WAVE 2 802.11ac products

like switch vs. hub

What is channel bonding?

When 2 adjacent 20-MHz channels can be bonded to make 40-MHz channel to increase overall size of bandwidth

What is frame aggregation?

Combination of multiple (more than 2) frames into a larger frame to reduce overhead %

How many bits are used in the physical addresses for 802.11?

48-bit for physical addresses

What other networking technology uses the same physical addressing scheme as 802.11 networks?

Ethernet networks

Why does 802.11 use a different access method than Ethernet?

Because wireless devices cannot prevent collisions and cannot transmit and receive at the same time.

What does CSMA/CA (Carrier Sense Multiple Access with Collision Avoidance) do?

Minimizes collision potential & Uses ACK packets to verify every transmission

What does RTS/CTS (Request to Send/Clear to Send) protocol do?

Ensures packets not inhibited by other transmissions & Further decreases overall 802.11 efficiency

What special frame is transmitted during active scanning?

a probe

What special signal is detected during passive scanning?

a beacon

What is SSID (service set identifier) & what is it contained in?

a unique character string identifying access point that is contained in a beacon frame

What is a BSS (basic service set)?

Group of stations sharing an access point

What is a BSSID (basic service set identifier)?

a group of stations identifier

What is ESS (extended service set)?

a group of access points that are connected to the same LAN, share an ESSID (extended service set identifier), and allows roaming

What happens in roaming?

devices moving from one BSS to another BSS within the same ESS causes the device *your phone) to re associate to a new AP (in the ESS) which can cause high error rate (temporary interruptions).

Sticky Client – What is it & Why Beware?

• What: A client application that does most processing locally and stores some data on the device.

• Why Beware:

  • Security risks (local data can be compromised)

  • Harder to update/maintain

  • Data consistency issues when syncing

  • Uses more device resources

What are 3 wireless topologies?

• ad hoc: a small # of nodes ‘talking’ directly to each other

• infrastructure: nodes ‘talk' to each other through a (usually 1) WAP (wireless access point) or AP (access point)

• mesh: nodes ‘talk‘ to each other through multiple WAP’s or AP’s, if one WAP/AP goes down communication can continue w/o interruption

What are 3 things a wireless controller can provide?

• centralized authentication for wireless clients

• channel management

• detection of rough access points

What is point-to-point (p2p) wireless?

Where wireless technology can be used to connect two different parts of a LAN or two separate LANs

3 things a home/small office network AP can do.

• have switching, routing functions

• connect wireless clients to LAN

• act as Internet gateway

What are 4 things to consider when installing an AP?

• distance

• coverage

• interference

• density

What systematic approach is needed for larger WLAN’s when installing AP’s?

Site survey:

• Assesses client requirements, facility characteristics, coverage areas

• Determines access point arrangement for best performance

What is the difference between on-boarding and off-boarding?

on-boarding: installing specific app on device to get trusted access from network

off-boarding: removing that app to revoke trusted access/permissions

What is a remote wipe?

• administrators are able to remotely erase all corporate data and apps from a lost or stolen smartphone.

• This protects proprietary corporate information from unauthorized access

What is MAC filtering?

Preventing the AP from authenticating any device whose MAC address is not listed

Which is stronger in WiFi protected access WPA: WPA, WPA2, ‘WPA OR WPA2’ - enterprise, WPA3

WPA < WPA2-Personal < WPA2-Enterprise < WPA3

What are 5 security threats to WiFi networks?

• War driving (VERY old school): A hacker searches for unprotected wireless networks by driving around with a laptop

• war chalking (VERY old school): Hackers draw symbols with chalk on the sidewalk near a vulnerable AP to make is known to other hackers

• evil twin (used a lot): A rogue AP in network’s geological area posing as authorized AP

• WPA attack: Interception of the network keys communicated between stations and APs

• WPS attack: Cracking a PIN to access an APs settings

To troubleshoot wireless LANs, you need tools that contain wireless NICs and run wireless protocols. Give 4 examples

• Mobile App “Wifi Analyzer”

• Laptop with WireShark

• AirMagnet

• Ekahau