NWT Quiz - Chapter 6

What identifier is used at the data link layer to uniquely identify an Ethernet device?

• IP address

• MAC address

• UDP port number

• TCP port number

• sequence number

Answer explanation

Ethernet frames are identified at the data link layer by their MAC addresses, which are unique to each NIC. IP addresses are used at the network layer, and TCP and UDP port numbers are used at the transport layer. Sequence numbers are fields in TCP headers.

What attribute of a NIC would place it at the data link layer of the OSI model?

• RJ-45 port

• IP address

• MAC address

• TCP/IP protocol stack

• attached Ethernet cable

Answer explanation

The data link layer describes media access and physical addressing. The encoding of a MAC address on a NIC places it at that layer. Ports and cables are placed at the physical layer of the OSI model. IP addresses are placed at the network layer. The TCP/IP protocol stack describes a different model.

Which two engineering organizations define open standards and protocols that apply to the data link layer? (Choose two.)

• Internet Society (ISOC)

• Internet Assigned Numbers Authority (IANA)

• International Telecommunication Union (ITU)

• Electronic Industries Alliance (EIA)

• Institute of Electrical and Electronics Engineers (IEEE)

Answer explanation

The IANA is responsible for overseeing and managing IP address allocation, domain name management, and protocol identifiers.

The EIA is an international standards and trade alliance for electronics organizations, and is best known for its standards related to electrical wiring, connectors, and the 19-inch racks used to mount networking equipment.

IEEE defines open standards and protocols that apply to the network access layer.

What is true concerning physical and logical topologies?

• The logical topology is always the same as the physical topology.

• Logical topologies refer to how a network transfers data between devices.

• Physical topologies are concerned with how a network transfers frames.

• Physical topologies display the IP addressing scheme of each network.

Answer explanation

Physical topologies show the physical interconnection of devices.

Logical topologies show the way the network will transfer data between connected nodes.

What method is used to manage contention-based access on a wireless network?

• CSMA/CA

• token passing

• priority ordering

• CSMA/CD

Answer explanation

Carrier sense multiple access with collision avoidance (CSMA/CA) is used with wireless networking technology to mediate media contention.

Carrier sense multiple access with collision detection (CSMA/CD) is used with wired Ethernet technology to mediate media contention. 

Priority ordering and token passing are not used (or not a method) for media access control.

A technician has been asked to develop a physical topology for a network that provides a high level of redundancy. Which physical topology requires that every node is attached to every other node on the network?

• mesh

• ring

• star

• hierarchical

• bus

Answer explanation

The mesh topology provides high availability because every node is connected to all other nodes. Mesh topologies can be found in WANs. A partial mesh topology can also be used where some, but not all, end points connect to one another.

Which statement describes the half-duplex mode of data transmission?

• Data that is transmitted over the network can only flow in one direction.

• Data that is transmitted over the network flows in one direction to many different destinations simultaneously.

• Data that is transmitted over the network flows in both directions at the same time.

• Data that is transmitted over the network flows in one direction at a time.

Answer explanation

The data that is transmitted over the network can flow using one of three modes:

- Simplex – Data can only flow in one direction.

- Half-duplex - Data flows in one direction at a time.

- Full-duplex - Data flows in both directions at the same time.

Which is a function of the Logical Link Control (LLC) sublayer?

• to provide data link layer addressing

• to accept segments and package them into data units that are called packets

• to identify which network layer protocol is being used

• to define the media access processes that are performed by the hardware

Answer explanation

Defining the media access processes that are performed by the hardware and providing data link layer addressing are functions of the MAC sublayer. The data link layer accepts Layer 3 packets and packages them into data units that are called frames.

Which data link layer media access control method does Ethernet use with legacy Ethernet hubs?

• token passing

• turn taking

• determinism

• CSMA/CD

Answer explanation

CSMA/CD is used by Ethernet networks using legacy Ethernet hubs. CSMA/CA is used by 802.11-based wireless networks.

What are the two sublayers of the OSI model data link layer? (Choose two.)

• transport

• MAC

• internet

• LLC

• network access

Answer explanation

The data link layer of the OSI model is divided into two sublayers: the Media Access Control (MAC) sublayer and the Logical Link Control (LLC) sublayer.