Network+ Chapter 2

A receiving host has failed to receive all the segments that it should acknowledge. What can the host do to improve the reliability of this communication session? Send a different source port number. Restart the virtual circuit. Decrease the sequence number. Decrease the window size.

A receiving host can control the transmitter by using flow control (TCP uses windowing by default). By decreasing the window size, the receiving host can slow down the transmitting host so the receiving host does not overflow its buffers.

Acknowledgments, sequencing, and flow control are characteristic of which OSI layer? Layer 2 Layer 3 Layer 4 Layer 7

A reliable Transport‐layer connection uses acknowledgments to make sure all data is received reliably. A reliable connection is defined by the use of acknowledgments, sequencing, and flow control, which is characteristic of the Transport layer (Layer 4).

Routers perform routing at which OSI layer? Physical Data Link Network Transport Application

A router is specified at the Network layer and a router routes packets. Routers can also be called layer‐3 switches.

Which of the following are types of flow control? (Choose all that apply.) Buffering Cut‐through Windowing Congestion avoidance VLANs

Buffering Windowing Congestion avoidance The common types of flow control are buffering, windowing, and congestion avoidance.

At which layers of the OSI model do bridges, hubs, and routers primarily operate, respectively? Physical, Physical, Data Link Data Link, Data Link, Network Data Link, Physical, Network Physical, Data Link, Network

Data Link, Physical, Network Bridges, like switches, are Data Link‐layer devices. Hubs, like repeaters, are Physical‐layer devices. Routers are Network‐layer devices

Which Layer 1 devices can be used to enlarge the area covered by a single LAN segment? (Choose two.) Switch NIC Hub Repeater RJ‐45 transceiver

Hub Repeater Not that you really want to enlarge a single collision domain, but a hub (multiport repeater) will provide this functionality for you.

At which layer of the OSI model would you find IP? Transport Network Data Link Physical

IP is a Network‐layer protocol. TCP is an example of a Transport‐layer protocol, Ethernet is an example of a Data Link‐layer protocol, and T1 can be considered a Physical‐layer protocol.

You are connected to a server on the Internet and you click on a link on the server and receive a time‐out message. What layer could be the cause of this message? Application Transport Network Physical

If the remote server is busy or does not respond to your web browser request, this is an Application layer problem.

Which layer manages the transmission of data across a physical link and is primarily concerned with physical addressing and the ordered delivery of frames?

PDUs at the Data Link layer are called frames. As soon as you see frame in a question, you know the answer

TCP and UDP reside at which layer of the OSI model? 1 2 3 4

TCP and UDP are Transport‐layer protocols. The Transport layer is Layer 4 of the OSI model

Which IEEE standard specifies the protocol for CSMA/CD? 802.2 802.3 802.5 802.11

The 802.3 standard, commonly associated with Ethernet, specifies the media‐access method used by Ethernet, which is known as Carrier Sense Multiple Access with Collision Detection (CSMA/CD).

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?

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).

Which layer combines bits into bytes and bytes into frames and uses MAC addressing?

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

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

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

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

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

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

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

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

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.

Which layer of the OSI model is responsible for converting data into signals appropriate for the transmission medium? Application Network Data Link Physical

The Physical layer's job is to convert data into impulses that are designed for the wired or wireless medium being used on the attached segment.

Of the following, which is the highest layer in the OSI model? Transport Session Network Presentation

The Presentation layer is the sixth layer of the model. Only the Application layer is higher, but it is not listed. Session is Layer 5, Transport is Layer 4, and Network is Layer 3.

Which layer of the OSI model is responsible for code and character‐set conversion as well as recognizing data formats? Application Presentation Session Network

The Presentation layer makes data "presentable" for the Application layer

Which layer defines how data is formatted, presented, encoded, and converted?

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

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

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

Segmentation of a data stream happens at which layer of the OSI model? Physical Data Link Network Transport

The Transport layer receives large data streams from the upper layers and breaks these up into smaller pieces called segments

Which layer is used for reliable communication between end nodes over the network and provides mechanisms for establishing, maintaining, and terminating virtual circuits as well as controlling the flow of information?

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

When data is encapsulated, which is the correct order? Data, frame, packet, segment, bits Segment, data, packet, frame, bits Data, segment, packet, frame, bits Data, segment, frame, packet, bits

The encapsulation order is data, segment, packet, frame, bits

Which of the following mnemonic devices can you use to remember the first letter of the name of each layer of the OSI model in the proper order? All People Seem To Need Processed Data Always Should People Never Threaten Dog Police Please Do Not Throw Sausage Pizza Away All Day People Should Try New Professions

The phrase "Please Do Not Throw Sausage Pizza Away" contains the first letters of the layers in order from Layer 1 through Layer 7. "All People Seem To Need Data Processing" works from the top down, but that's not exactly how the option that looks similar, reads.

Which layer of the OSI model provides a user interface in the form of an entry point for programs to access the network infrastructure? Application Transport Network Physical

The top layer of the OSI model gives applications access to the services that allow network access.

What are two purposes for segmentation with a bridge? To add more broadcast domains To create more collision domains To add more bandwidth for users To allow more broadcasts for users

To create more collision domains To add more bandwidth for users Bridges and switches break up collision domains, which allow more bandwidth for users.

What is the purpose of flow control? To ensure that data is retransmitted if an acknowledgment is not received To reassemble segments in the correct order at the destination device To provide a means for the receiver to govern the amount of data sent by the sender To regulate the size of each segment

To provide a means for the receiver to govern the amount of data sent by the sender

Host 1 sent a SYN packet to Host 2. What will host 2 send in response? ACK NAK SYN‐ACK SYN‐NAK SYN

To set up a connection‐oriented session, called a three‐way handshake, the transmitting host sends a SYK packet, the receiving host sends a SYK‐ACK, and the transmitting host replies with the last SYN packet. The session is now set up.