1. What is another name for the OSI data link layer?

2. The IEEE 802 LAN/MAN data link layer consists of which two sublayers? (Choose two.)

3. What is the responsibility of the MAC sublayer?

4. What Layer 2 function does a router perform? (Choose three.)

5. The media access control method used depends on which two criteria?

6. Which organization defines standards for the network access layer (i.e., the OSI physical and data link layers)?

7. Which topology displays networking device layer IP addresses?

8. What kind of network would use point-to-point, hub and spoke, or mesh topologies?

9. Which LAN topology is a hybrid topology?

10. Which duplex communication method is used in WLANs?

11. Which media access control method is used in legacy Ethernet LANs?

12. What does the data link layer add to a Layer 3 packet to create a frame? (Choose two.)

13. What is the function of the last field in a data link layer frame?

14. Which lists the Layer 2 and Layer 3 address fields in the correct order?

15. Which of the following are data link layer protocols? (Choose three)

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

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.

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

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.

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

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.

19. What is true concerning physical and logical topologies?

Physical topologies show the physical interconnection of devices. Logical topologies show the way the network will transfer data between connected nodes.

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

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.

21. 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?

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.

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

The data that is transmitted over the network can flow using one of three modes: o Simplex – Data can only flow in one direction. o Half-duplex – Data flows in one direction at a time. o Full-duplex – Data flows in both directions at the same time.

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

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.

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

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

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

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.

26. Which layer of the OSI model is responsible for specifying the encapsulation method used for specific types of media?

Encapsulation is a function of the data link layer. Different media types require different data link layer encapsulation.

27. What type of physical topology can be created by connecting all Ethernet cables to a central device?

Devces connected to the Ethernet star topology connect to either a hub or a switch.

28. What are two services performed by the data link layer of the OSI model? (Choose two.)

The data link layer is responsible for the exchange of frames between nodes over a physical network media. Specifically the data link layer performs two basic services: o It accepts Layer 3 packets and encapsulates them into frames. o It provides media access control and performs error detection. Path determination is a service provided at Layer 3. A Layer 2 switch builds a MAC address table as part of its operation, but path determination is not the service that is provided by the data link layer.

29. Although CSMA/CD is still a feature of Ethernet, why is it no longer necessary?

The use of Layer 2 switches operating in full-duplex mode eliminates collisions, thereby eliminating the need for CSMA/CD.