Help Please!!!!!! QUESTION 1 For a local area network (LAN), the physical topolo

Question

Help Please!!!!!!

QUESTION 1

For a local area network (LAN), the physical topology must always be the same as the logical topology.

True

False

QUESTION 2

Select the correct statement(s) regarding the use of centralized control over a LAN, WLAN, or WPAN.

a. Centralized control represents a medium access mode in which each network node determines when it can place data onto a shared medium

b. Centralized control provides non-deterministic access to the medium

c. The use of tokens or polling is key to centralized control

d. All of the above are correct

QUESTION 3

Ethernet 802.3 LANs use CSMA/CD. What happens when a collision is detected on the shared medium?

a. The node closet to the collision sends out a jamming signal to inform all other nodes that a collision has occurred

b. A central control node sends out a jamming signal to inform all other nodes that a collision has occurred

c. Collisions do not occur on Ethernet LANs

d. All LAN nodes detect the collision, which tells them to cease any data transfer activity

QUESTION 4

Either CSMA/CD or CSMA/CA can be used on 802.11 WLANs.

True

False

QUESTION 5

Select the correct statement(s) regarding shared and switched Ethernet LANs.

a. All Ethernet LANS, whether shared or switched, full-duplex or half-duplex, require CSMA/CD

b. Shared and Switched full-duplex LANs do not require CSMA/CD since collisions cannot occur

c. Switched full-duplex LANs do not require CSMA/CD since collisions cannot occur

d. Only shared half-duplex LANs require CSMA/CD

QUESTION 6

What does 100BaseT mean?

a. 100 Mbps, baseband, twisted pair

b. 100 bps, baseband, twisted pair

c. 100 meters, baseband, transmit

d. 100 kilometers, baseband, transmit

QUESTION 7

Select the correct statement(s) regrading the 802.3 MAC layer.

a. The MAC layer resides in the data link layer 2, under the LLC

b. The MAC layer is where the 48 bit data link address resides

c. MAC is responsible for contention-based access (i.e., CSMA/CD or CSMA/CA)

d. All of the above are correct

QUESTION 8

10GBase-T is possible over Cat5e UTP.

True

False

  QUESTION 9

Select the correct statement(s) regarding 802.11 WLANs.

a. Operates over unlicensed ISM frequencies

b. Implements spread spectrum or OFDM techniques for better noise resistance and spectral efficiency

c. Uses CSMA/CA since collisions are always possible

d. All of the above are correct

QUESTION 10

For 802.11 WLANs, the four frame exchange protocol is implemented to help avoid the hidden nodeproblem.

True

False

a. Centralized control represents a medium access mode in which each network node determines when it can place data onto a shared medium

b. Centralized control provides non-deterministic access to the medium

c. The use of tokens or polling is key to centralized control

d. All of the above are correct

Explanation / Answer

Q1.

For a local area network (LAN), the physical topology must always be the same as the logical topology.

No it is False.

The physical topology describes the layout of the network, and the logical topology describes how the data is sent accross the network i.e the direction and speed.

Q2.

In question two for the centralized control over LAN, WLAN, WPAN all of the options given are correct.

Q3.

In Ethernet 802.3 LANs use CSMA/CD, When a collision is detected on the shared medium ,The node closet to the collision sends out a jamming signal to inform all other nodes that a collision has occurred.

CSMA/CD works by each node checking that the media is not being used before placing its message to the line. The node will continue to listen throughout the transmission and if a collision occurs then sending station will stop transmission and put a jamming signal on the line to warn all nodes to hold back. The transmitting nodes will apply a 'backoff algorithm' to generate a random time before they try to transmit again.

i.e option A is correct.

Q4.

Yes it is true that either CSMA/CD or CSMA/CA can be used on 802.11 WLANs.

Q5.

Since switches are now commonly used in networks instead of hubs, CSMA/CD is not really used anymore. Each port on a swich usually operate in a full duplex mode and there are no packet collisions in a full duplex mode.Hence from the given options option B is correct.

Q6.

What does 100BaseT mean?

It is an ethernet standard that transmits 100Mbps, i.e option A is correct.

Q7.

All the above statements are correct about the Mac layer. i.e option D is correct.

Q8.

Yes it is possible to use 10GBase-T over Cat5e UTP. But it is suggested that you need to use Cat6a or Cat7 cable to reach the full distance potential.

Distances:

Q9.

Regarding to 802.11 Wlan all the above options given are correct.

Q10.

Yes it is TRUE that the four frame exchange protocol is implemented to help avoid the hidden nodeproblem.

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