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04 - CMSA/CA and RTS/CTS

 1. CSMA/CA is …

  a way of accelerating wireless signals

  a Wi-FI network with more than one WAP

  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.

  TRUE

  FALSE

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

  four devices

  two devices

  three devices

  one device

 4. CSMA stands for …

  Carrier Sensitive Meeting Avoidance

  Carrier Sense Multiple Access

  Co-ordinated Signal Maintenance Area

  Clear Signal Memory Address

 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

  strong

  occupied

  clear

  cloudy

 6. CA stands for ...

  Collision Agreement

  Collision Activation

  Collision Avoidance

  Collision Antithesis

 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?

  There is no particular benefit

  It will be more difficult for hackers to listen to transmissions

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

  This will speed up the gaps between 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 …

  disguised device problem

  covert device problem

  hidden node problem

  redundant 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.

  handshake

  embrace

  beeline

  javelin

 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.

  relative importance

  byte size

  total weight

  measured priority