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04 - CMSA/CA and RTS/CTS

 1. CSMA/CA is …

  a Wi-FI network with more than one WAP

  a way of accelerating wireless signals

  a protocol to avoid transmission collisions

  a method of encrypting wireless signals

 2. Five laptops are connected to a WLAN. If they all send a signal to the WAP at the same time, this won't cause any problem.

  FALSE

  TRUE

 3. Collisions are a concern for any network, because only ___ _____ can send a signal simultaneously without the risk of collision.

  three devices

  four devices

  two devices

  one device

 4. CSMA stands for …

  Carrier Sense Multiple Access

  Clear Signal Memory Address

  Co-ordinated Signal Maintenance Area

  Carrier Sensitive Meeting Avoidance

 5. Using CSMA, a node will listen for signals before it sends a packet. If it detects the channel is ____ it will transmit the packet.
CSMA_CA_q5.png

  cloudy

  strong

  occupied

  clear

 6. CA stands for ...

  Collision Avoidance

  Collision Antithesis

  Collision Agreement

  Collision Activation

 7. CSMA/CA means if the channel is busy, the node will usually wait a 'random' period of time until it tries to send the packet again. Why does it help if this time period is random?

  So that multiple nodes won't keep trying to send data at exactly the same time

  This will speed up the gaps between transmissions

  There is no particular benefit

  It will be more difficult for hackers to listen to transmissions

 8. If nodes are out of range of each other, they may not be able to detect if the channel is busy. This is known as the …

  redundant node problem

  disguised device problem

  covert device problem

  hidden node problem

 9. This issue can be mitigated by Request to Send/Clear to Send (RTS/CTS) . RTS/CTS is like a _______ between the node and the wireless access point.

  javelin

  embrace

  beeline

  handshake

 10. As RTS/CTS slows down data transfer, routers and nodes usually have an adjustable threshold based on the _____ ____ of a packet, below which they will not use RTS/CTS.

  measured priority

  byte size

  relative importance

  total weight


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