Internetworking

Question: Which of the following types of connections can use full duplex?

[A].

1, 2 and 4

[B].

3 and 4

[C].

3 and 5

[D].

2, 3 and 5

Answer: Option D

Explanation:

Hubs cannot run full-duplex Ethernet. Full duplex must be used on a point-to-point connection between two devices capable of running full duplex. Switches and hosts can run full duplex between each other, but a hub can never run full duplex.

Question: Acknowledgments, sequencing, and flow control are characteristics of which OSI layer?
[A].

Layer 2

[B].

Layer 3

[C].

Layer 4

[D].

Layer 7

Answer: Option C

Explanation:

A reliable Transport layer connection uses acknowledgments to make sure all data is transmitted and received reliably. A reliable connection is defined by a virtual circuit that uses acknowledgments, sequencing, and flow control, which are characteristics of the Transport layer (layer 4).

Question: Why does the data communication industry use the layered OSI reference model?

[A].

1 only

[B].

1 and 4

[C].

2 and 3

[D].

3 only

Answer: Option B

Explanation:

The main advantage of a layered model is that it can allow application developers to
change aspects of a program in just one layer of the layer model’s specifications.

Advantages
of using the OSI layered model include, but are not limited to, the following:

It divides the
network communication process into smaller and simpler components, thus aiding compo-
nent development, design, and troubleshooting;

it allows multiple-vendor development
through standardization of network components;

it encourages industry standardization by
defining what functions occur at each layer of the model;

it allows various types of network
hardware and software to communicate;

and it prevents changes in one layer from affecting
other layers, so it does not hamper development.

Question: A receiving host has failed to receive all of the segments that it should acknowledge. What can the host do to improve the reliability of this communication session?
[A].

Send a different source port number.

[B].

Restart the virtual circuit.

[C].

Decrease the sequence number.

[D].

Decrease the window size.

Answer: Option D

Explanation:

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.