OSI Data Link Layer

Question 1

What are the two common LAN sublayers?

Answer 1

Logical Link Control (LLC) and Media Access Control (MAC)

Question 2

What is the role of the data link layer in data transmission?

Answer 2

To prepare data for transmission on network media

Question 3

What does LLC (Logical Link Control) do?

Answer 3

Places information in the frame that identifies which network layer protocol is being used for the frame

Question 4

What is the MAC (Media Access Control) method?

Answer 4

The technique used for getting the frame on and off media

Question 5

Which device usually processes the frame at each hop along the path?

Answer 5

A router

Question 6

What is the data link layer responsible for?

Answer 6

The exchange of frames between nodes over the media of a physical network

Question 7

What is the purpose of encapsulating packets into frames?

Answer 7

To facilitate media access

Question 8

What organizations define open standards and protocols that apply to the data link layer?

Answer 8

International Organization for Standardization (ISO), Institute of Electrical and Electronics Engineers (IEEE), American National Standards Institute (ANSI), International Telecommunication Union (ITU)

Question 9

What organization is responsible for defining open standards and protocols related to the data link layer?

Answer 9

International Organization for Standardization (ISO)

Institute of Electrical and Electronics Engineers (IEEE)

American National Standards Institute (ANSI)

Question 10

What is the role of the data link layer in data transmission?

Answer 10

To prepare data for transmission on network media

Question 11

What are the two common LAN sublayers?

Answer 11

Logical Link Control (LLC) and Media Access Control (MAC)

Question 12

What does LLC do?

Answer 12

Places information in the frame that identifies which network layer protocol is being used for the frame

Question 13

What is the MAC method?

Answer 13

The technique used for getting the frame on and off media

Question 14

Which device usually processes the frame at each hop along the path?

Answer 14

A router

Question 15

What is the purpose of encapsulating packets into frames?

Answer 15

To facilitate media access

Question 16

Which organizations define open standards and protocols that apply to the data link layer?

Answer 16

International Organization for Standardization (ISO), Institute of Electrical and Electronics Engineers (IEEE), American National Standards Institute (ANSI), International Telecommunication Union (ITU)

Question 17

What are the three elements of data link layer frame?

Answer 17

• Data
• Header
• Trailer

Question 18

It is an Ethernet that is inserted into the bus system of the computer and makes the connection between running software processes on the computer and the physical media.

Answer 18

Network Interface Card (NIC)

Question 19

What is contained within the frame header?

Answer 19

Start of Frame field

Question 20

What is CSMA?

Answer 20

A media access method used in multiaccess topology

Question 21

What is CSMA/CD?

Answer 21

A method for resolving media contention in shared media and the device monitors the media for the presence of data signal

Question 22

What is the purpose of the trailer?

Answer 22

To check for errors

Question 23

What is the purpose of PPP authentication?

Answer 23

To authenticate the nodes on each end of the PPP link

Question 24

What are the three functions and subfunctions of an 802.11 frame?

Answer 24

control, data, and management

Question 25

What is the purpose of MAC addressing?

Answer 25

To specify the frame destination node on the local network

Question 26

What is the purpose of the FCS field in a PPP frame?

Answer 26

to provide improved error detection

Question 27

What is the binary sequence for the flag field in a PPP frame?

Answer 27

01111110

Question 28

What is the difference between scheduled access and nondeterministic access in shared media?

Answer 28

Scheduled access takes turns for devices to access the medium, while nondeterministic access first detects whether the media is carrying a signal before allowing any device to try to access it

Question 29

What is the purpose of addressing in the data link layer?

Answer 29

To specify the frame destination node on the local network

Question 30

What is the difference between CSMA/CD and CSMA/CA?

Answer 30

CSMA/CD monitors the media for the presence of a data signal, while CSMA/CA examines the media for the presence of a data signal

Question 30

What is the purpose of the Protocol Version field in an 802.11 frame?

Answer 30

to indicate the version of 802.11 frame in use

Question 30

What is the purpose of the Frame Check Sequence (FCS) field?

Answer 30

To check for errors

Question 31

What is the purpose of the Authentication option in PPP?

Answer 31

To require the nodes on each end of the PPP link to authenticate in order to establish communications over a point-to-point link

Question 32

What is the difference between logical and physical topology in a network?

Answer 32

Physical topology refers to the physical arrangement of nodes and connections, while logical topology refers to the way a network transfers frames from one node to the next

Question 33

What is the purpose of the Stop field in the frame trailer?

Answer 33

To indicate the end of the frame

Question 34

What is the difference between physical and logical addresses in the data link layer?

Answer 34

Physical addresses are contained within the frame header, while logical addresses are used only for local delivery.

Question 35

What is the standard PPP broadcast address?

Answer 35

a single byte that contains the standard PPP broadcast address

Question 36

What is a ring topology?

Answer 36

A topology in which each node in turn receives a frame

Question 36

What is the purpose of the To DS field in an 802.11 frame?

Answer 36

To identify frames destined for the distribution system (devices in the wireless structure)

Question 36

What is the purpose of the Sequence Number field in an 802.11 frame?

Answer 36

To indicate the sequence number assigned to the frame; retransmitted frames are identified by duplicate sequence numbers

Question 37

What options can be negotiated in a PPP session?

Answer 37

Compression Authentication Multilink

Question 38

What is the purpose of the Preamble field in Ethernet frames?

Answer 38

To indicate the beginning of the frame

Question 39

What is the difference between controlled access and contention-based access in shared media?

Answer 39

Controlled access takes turns for devices to access the medium, while contention-based access first detects whether the media is carrying a signal before allowing any device to try to access it

Question 40

What is a point-to-point topology?

Answer 40

A topology that connects two nodes directly

Question 41

What is the purpose of the Power Management field in an 802.11 frame?

Answer 41

to indicate that a node will be in power-save mode

Question 42

What is the purpose of the frame header?

Answer 42

To contain the control information specified by the data link layer protocol