Chapter 1 - Internetworking

Question 1

What are the 4 primary possible causes of LAN traffic congestion?

Answer 1

Too many hosts in a broadcast domain, broadcast storms, multicasting, and low bandwidth.

Question 2

What is the difference between a collision domain and a broadcast domain?

Answer 2

Collision domain is a collection of devices on a network segment in which all nodes can transmit packets at the same time, causing data collisions and slowing traffic. With a broadcast domain, a set of all devices on a network hear all broadcasts sent on all segments.

Question 3

Differentiate a MAC address and an IP address and describe how and when each address type is used in a network.

Answer 3

A MAC address is a hexadecimal number identifying the physical connection of a host which operate on layer 2 of the OSI model. IP addresses, which can be expressed in binary or decimal format, are logical identifiers that are said to be on layer 3 of the OSI model. Hosts on the same physical segment locate one another with MAC addresses, while IP addresses are used when they reside on different subnets.

Question 4

Understand the difference between a hub, a bridge, a switch, and a router.

Answer 4

A hub creates one collision domain and one broadcast domain. A bridge breaks up collision domains but creates one large broadcast domain. Switches are really just multiple-port bridges with more intelligence; they break up collision domains but creates one large broadcast domain by default. Bridges and switches use hardware addresses to filter the network. Routers break up broadcast domains (and collision domains) and use logical addressing to filter the network.

Question 5

Identify the functions and advantages of routers.

Answer 5

Routers perform packet switching, filtering, and path selection, and they facilitate internetwork communication. They also reduce broadcast traffic.

Question 6

Differentiate connection-oriented and connectionless network services and describe how each is handled during network communications.

Answer 6

Connection-oriented services use acknowledgments and flow control to create a reliable session. More overhead is used than in a connectionless network service. Connectionless services are used to send data with no acknowledgments or flow control. This is considered unreliable.

Question 7

Define the OSI layers, understand the function of each, and describe how devices and networking protocols can be mapped to each layer.

Answer 7

7 - Application
6 - Pressentation
5 - Session
These are the upper layers and are responsible for communicating from a user interface to an application.
4 - Transport: provides segmentation, sequencing, and virtual circuits.
3 - Network: provides logical network addressing and routing through an internetwork.
2 - Data Link: provides framing and placing of data on the network medium.
1 - Physical: responsible for taking 1s and 0s and encoding them into a digital signal for transmission on the network segment.

Question 8

Which layer chooses and determines the availability of communicating partners along with the resources necessary to make the connection; coordinates partnering applications; and forms a consensus on procedures for controlling data integrity and error recovery?

Answer 8

The application layer is responsible for finding the network resources broadcast from a server and adding flow control and error control (if the application developer chooses)

Question 9

Which layer is responsible for converting data packets from the Data Link layer into electrical signals?

Answer 9

The Physical layer takes frames from the Data Link layer and encodes the 1s and 0s into a digital signal for transmission on the network medium,

Question 10

At which layer is routing implemented, enabling connections and path selection between two end systems?

Answer 10

The Network layer provides routing through an internetwork and logical addressing.

Question 11

Which layer defines how data is formatted, presented, encoded, and converted for use on the network?

Answer 11

The Presentation layer makes sure that data is in a readable format for the Application layer.

Question 12

Which layer is responsible for creating, managing, and terminating sessions between applications?

Answer 12

The Session layer sets up, maintains, and terminates sessions between applications.

Question 13

Which layer ensures the trustworthy transmission of data across a physical link and is primarily concerned with physical addressing, line discipline, network topology, error notification, ordered delivery of frames, and flow control?

Answer 13

PDUs at the Data Link layer are called frames and provide physical addressing plus other options to place packets on the network medium.

Question 14

Which layer is used for reliable communication between end nodes over the network and provides mechanisms for establishing, maintaining, and terminating virtual circuits; transport-fault detection and recovery; and controlling the flow of information?

Answer 14

The Transport layer uses virtual circuits to create a reliable connection between two hosts.

Question 15

Which layer provides logical addressing that routers will use for path determination?

Answer 15

The Network layer provides logical addressing, typically IP addressing and routing.

Question 16

Which layer specifies voltage, wire speed, and cable pinouts and moves bits between devices?

Answer 16

The Physical layer is responsible for the electrical and mechanical connections between devices.

Question 17

Which layer combines bits into bytes and bytes into frames, uses MAC addressing, and provides error detection?

Answer 17

The Data Link layer is responsible for the framing of data packets.

Question 18

Which layer is responsible for keeping the data from different applications separate on the network?

Answer 18

The Session layer creates sessions between different hosts’ applications.

Question 19

Which layer is represented by frames?

Answer 19

The Data Link layer frames packets received from the Network layer.

Question 20

Which layer is represented by segments?

Answer 20

The Transport layer segments user data.

Question 21

Which layer is represented by packets?

Answer 21

The Network layer creates packets out of segments handed down from the Transport layer.

Question 22

Which layer is represented by bits?

Answer 22

The Physical layer is responsible for transporting 1s and 0s (bits) in a digital signal.

Question 23

Put the following in order of encapsulation:

• Packets
• Frames
• Bits
• Segments

Answer 23

Segments, packets, frames, bits

Question 24

Which layer segments and reassembles data into a data stream?

Answer 24

Transport.

Question 25

Which layer provides the physical transmission of the data and handles error notification, network topology, and flow control?

Answer 25

Data Link

Question 26

Which layer manages logical device addressing, tracks the location of devices on the internetwork, and determines the best way to move data?

Answer 26

Network

Question 27

What is the bit length and expression form of a MAC address?

Answer 27

48 bits (6 bytes) expressed as a hexadecimal number.