Answers to Review Questions ( Network+ Chapter 2 )

Answers to Review Questions

1. B. Of the layers listed, the only OSI layer that is responsible for reliable end-to-end communications is the Transport layer. The Network layer is responsible for logical network addresses,
the Session layer is responsible for opening sessions and maintaining session information, and the Presentation layer is responsible for how data “looks” to the upper layer(s).

2. D. Of the OSI model layers listed, the Network layer is the only one that is responsible for routing information because it contains information for logical network addressing.

3. A. The Physical layer, as its name suggests, is the layer responsible for placing electrical transitions on the physical media. The other layers are all upper layers.

4. D. The 802.5 standard is similar to the Token Ring technology developed by IBM. That technology scales well and could handle more than 1000 users without bridging or additional segments.
Also, the performance would be better than that of any of the other technologies listed.

5. D. Routers will not propagate broadcasts from one of their ports to another. The other devices will. Each interface on a router is in a different broadcast domain.

6. D. By sending out packets to their own IP address, both workstations will detect if there is a duplicate IP address on the network and will display error messages to that effect.

7. A. Because workstation A had a valid IP address to begin with, Windows takes a first come, first served approach with the IP addresses and lets workstation A keep its IP address. Workstation
B detects that A already has it and just deactivates its own IP stack.

8. C. Each port on a switch belongs to a different collision domain, such that any device attached to one port on the switch cannot be involved in a collision with a device attached to a different
port on the switch. Inserting a switch into a LAN segment serves the purpose of increasing the number of collision domains and reducing the average number of nodes per collision domain.

9. C, E. TFTP and NetBIOS both use a connectionless transport (UDP and NetBEUI, respectively). TCP is, in fact, a connection-oriented transport protocol. HTTP uses TCP, so it is therefore connection oriented. And IP is a Network layer protocol.

10. C. Of all the protocols listed, HTTP is the only one that uses a connection-oriented Transport layer protocol (TCP). The others use, or are themselves, connectionless Transport layer protocols.
11. A. Although WINS is a name resolution that does translate NetBIOS names to IP addresses, it works only on Windows-based networks. The only true name resolution system that almost
every TCP/IP network uses is DNS.

12. D. The Data Link layer is divided into two sublayers: the MAC sublayer and an LLC sublayer. The other layers aren’t normally subdivided.

13. C. The Session layer is responsible for establishing, maintaining, and breaking down dialog.

14. C. The Presentation layer handles such services as data formatting, compression, encryption, and data-set conversion, such as from ASCII to Unicode or EBCDIC.

15. A. The Network layer is responsible for packaging data into packets. Different terms for data packages (such as frames) are used when discussing the other layers.

16. B. The first half of the MAC address is the Organizationally Unique Identifier (OUI), and the second half is the device ID.
17. B, C. Of the directory services listed, only Microsoft’s Active Directory and the Linux password shadow file are hierarchical in design.

18. C. A switch would increase performance by making virtual, direct connections between sender and receiver. Bridges and routers actually decrease performance because these devices introduce latency into the communication. Replacing the hub with an NIC just can’t be done.

19. D. Because routers deal with logical network addresses, they operate at the Network layer.

20. C. MAC addresses use a 12-digit hexadecimal number that is separated into six pairs of hex numbers. The only one that corresponds to that format is Answer C.