CertiGuide to Network+  9  Appendix A: Answers to Success Questions and Real World Exam Questions

Chapter 0010: OSI and IEEE Network Standards Answers 1 Chapter 0100: Network Protocols Answers

1. How many Ethernet collision domains are created when you connect two active hubs together?

A. Two

B. One

C. None

D. Depends on the distance

E. Depends on the cable type

Explanation: Hubs, whether active or passive, always share the same collision domain. Only bridges, routers, or switches can break up collision domains

& Domain 2.4: Identify the OSI layers at which the following network components operate. Hubs - Layer 1 Physical Layer

2. When would a Brouter be useful?

A. To connect two or more segments of similar topology

B. Where continuous bridge looping occurs

C. Where both routable an non-routable protocols exist

D. To save on company hardware expenses

E. To eliminate non-routable broadcasts packets

Explanation: Brouters are ideal in environments where both routable and non-routable protocols exist. If a packet contains routable information, the brouter will route it, otherwise it will be bridged.

& Domain 1.6: Identify the purpose, features, and functions of following network components: hubs, switches, bridges, routers, gateways, and CSU/DSU, never to raise car/ISDN adapter/Network Interface cards, wireless access points, modems.

3. If your Ethernet LAN contains a large number of devices and performance is getting poor, what type of device can you install to create more collision domains?

A. A hub

B. An RJ45 CAT5 cable system

C. A Bridge

D. A NIC

Explanation: Bridges create multiple collision domains by separating traffic based on the MAC address of the devices. This makes a bridge a Layer 2 device in the OSI model.

& Domain 1.6: Identify the purpose, features, and functions of the following network components: hubs, switches, bridges, routers, gateways, CSU/DSU, network interface cards/ISDN adapters/System area Network cards, wireless access points, modems.

4. At what layer are hardware addresses maintained?

A. Physical

B. Data Link

C. Session

D. Transport

E. Application

Explanation: Physical (MAC) addresses are maintained at the data link layer.

& Domain 2.4: Identify the OSI layers at which the following network components operate hubs, switches, bridges, routers, network interface cards

5. What layer of the OSI model would be concerned with user applications such as word processing and spreadsheets?

A. None. This level of functionality is not addressed with the OSI model

B. The Application layer

C. The Program layer

D. The TCP/IP Layer

E. The IP layer

Explanation: Although word documents and spreadsheets are created in "applications" such as WordPerfect or Lotus, they are not to be confused with the Application layer of the OSI model. The Application layer of the OSI model does not support "user applications" or software. It provides network services such as file transport, e-mail, and terminal emulation.

& Domain 2.2: Identify the seven layers of the OSI model and their functions

6. Which OSI layer initiates retransmit requests?

A. The Transport Layer 4

B. The Network Layer 3

C. The Physical Layer 1

D. The Session Layer 5

E. The Application Layer 7

Explanation: Layer 4 (the transport layer) is responsible for ensuring that data is sent and received successfully. If 5mb of data is sent, but only 4 received, it is the transport layer's job to request the sending device to retransmit the missing data.

& Domain 2.2: Identify the seven layers of the OSI model and their functions

7. What is the hop count of a packet that transverses 1 hub, 2 bridges and 1 router?

A. 3

B. 2

C. 1

D. 0

E. 12ms

Explanation: Hops are counted only when a packet is routed between two network segments, such as the case with bridges and routers. Hubs do not transverse across segments, and therefore do not add to the hop count.

& Domain 2.4: Identify the OSI layers to which the following network components operate: Hubs, Switches, Bridges, Routers, Network Interface Cards.

8. You are working in a company with several hundred computers. Each major department is on its own subnet. What can be used to prevent broadcast storms from crossing departments? (Choose all that apply).

A. Network hub

B. LAN switch

C. LAN Bridge

D. LAN router

E. Server NIC

Explanation: A hub will not prevent broadcast storms across subnets because they work at the physical layer of the OSI model. Their sole function is to repeat what they have been given. A bridge and a switch operate within the IEEE sub-layer (data-link layer) of the OSI model. By examining the MAC address found in the data-link layer, neither a bridge nor a switch will forward network packets sent in error. A router examines IP packets on the network layer (layer 3) of the OSI model, which would reject erroneous IP packets. A server NIC is simply an intelligent NIC that operates on the physical layer therefore is incapable of distinguishing genuine traffic from a broadcast storm.

& Domain 2.4: Identify the OSI layers to which the following network components operate: Hubs, Switches, Bridges, Routers, Network Interface Cards.

9. Which OSI layer defines electrical specifications?

A. Network

B. Presentation

C. Application

D. Physical

E. Data link

Explanation: The Physical Layer describes, amongst other things, the electrical properties and interpretation of the exchanged signals.

& Domain 2.2: Identify the 7 layers of the OSI model and their functions.

10. Packaging raw bits of data into frames (logical, structured packets for data) and transferring those frames from one computer to another without errors is the responsibility of the _________layer.

A. Data Link

B. Session layer

C. Application Layer

D. Network layer

E. Transport layer

Explanation: The data link layer takes all the data that the device in the physical layer provides and gets it ready for the network layer.

& Domain 2.2: Identify the 7 layers of the OSI model and their functions.

11. Which layer of the OSI model is responsible for establishing, maintaining, and terminating connections?

A. Physical Layer

B. Data Link layer

C. Network layer

D. Application layer

E. Session layer

Explanation: The session layer sets up, coordinates, and terminates conversations between applications at each end of the connection.

& Domain 2.2: Identify the 7 layers of the OSI model and their functions.

12. Which of the following devices translates protocols?

A. Router

B. Gateway

C. Bridge

D. Server

E. Switch

Explanation: The term "gateway" refers to a physical device called a router, which translates protocols. It is referred to as the gateway because it acts as a gateway into, and out of, a network.

Most people who have cable internet access use a router, not a modem, to connect to the Internet. The router is the gateway to the Internet, which itself is one huge network.

& Domain 2.4: Identify the OSI layers to which the following network components operate: Hubs, Switches, Bridges, Routers, Network Interface Cards.

13. Which OSI layer establishes, manages, and terminates communications between two computers?

A. Session

B. Transport

C. Network

D. Data-link

E. Application

Explanation: The session layer establishes, manages, and terminates communications between computers.

& Domain 2.2: Identify the 7 layers of the OSI model and their functions.

14. Bridges operate at the _______ layer of the OSI model.

A. Data Link

B. Top

C. Transport

D. Session

E. Network

Explanation: The data link layer actually consists of two sub-layers: the MAC sub-layer and the Logical Link sub-layer, which is where the bridge functions.

& Domain 2.2: Identify the 7 layers of the OSI model and their functions.

15. While implementing video conferencing on your network, you notice that your existing hub is a bottleneck. What can you do to make your network more efficient?

A. Install a router

B. Install a switch

C. Switch to 10Base5 technology

D. Install a repeater

E. Remove unnecessary protocols

Explanation: A switch provides the same function as a hub, but has the ability to route traffic directly to the destination host instead of broadcasting it to ALL hosts, which is what a hub does.

& Domain 2.4: Identify the OSI layers to which the following network components operate: Hubs, Switches, Bridges, Routers, Network Interface Cards.

Chapter 0010: OSI and IEEE Network Standards Answers 1 Chapter 0100: Network Protocols Answers