Internetworking MCQs with Explanations

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

Routers operate at layer 3. LAN switches operate at layer 2. Ethernet hubs operate at layer 1. Word processing applications communicate to the Application layer interface, but do not operate at layer 7, so the answer would be none.

Routers provide packet switching, packet filtering, internetwork communication, and path selection.

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.

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.

You must be able to take a binary number and convert it into both decimal and hexadecimal. To convert to decimal, just add up the 1s using their values. The values that are turned on with the binary number of 10110111 are 128 + 32 + 16 + 4 + 2 + 1 = 183 . To get the hexadecimal equivalent, you need to break the eight binary digits into nibbles (4 bits), 1011 and 0111 . By add-ing up these values, you get 11 and 7 . In hexadecimal, 11 is B , so the answer is 0xB7 .

Flow control allows the receiving device to control the transmitter so the receiving device's buffer does not overflow.

Full-duplex means you are using both wire pairs simultaneously to send and receive data. You must have a dedicated switch port for each node, which means you will not have collisions. Both the host network card and the switch port must be capable and set to work in full-duplex mode.

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

Bridges break up collision domains, which allow more bandwidth for users.

Once transmitting stations on an Ethernet segment hear a collision, they send an extended jam signal to ensure that all stations recognize the collision. After the jamming is complete, each sender waits a predetermined amount of time, plus a random time. After both timers expire, they are free to transmit, but they must make sure the media is clear before transmitting and that they all have equal priority.

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.

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).

An Ethernet frame has source and destination MAC addresses, an Ether-Type field to identify the Network layer protocol, the data, and the FCS field that holds the answer to the CRC.

To connect to a router or switch console port, you would use an RJ45 UTP rolled cable.

Fiber-optic cable provides a more secure, long-distance cable that is not susceptible to EMI interference at high speeds.

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

The encapsulation method is data, segment, packet, frame, bit.

Unlike full duplex, half-duplex Ethernet operates in a shared collision domain, and it has a lower effective throughput than full duplex.

Correct Answer: B) Crossover cable Here's why: Imagine two switches are like two people trying to talk. * Option A: Straight-through cable: Think of this like both people trying to speak at the same time and both listening at the same time. They can't hear each other because their "talking" (transmit) lines are connected to each other and their "listening" (receive) lines are connected to each other. It doesn't work for two switches directly connected. * Option B: Crossover cable: This cable is specially wired so that one person's "talking" (transmit) goes to the other person's "listening" (receive), and vice-versa. This is exactly what you need when connecting two switches directly! * Option C: Crossover with a CSU/DSU: A CSU/DSU is a device used for connecting to a WAN (Wide Area Network) link, like a T1 line. It's not needed for connecting two switches locally. * Option D: Crossover with a router in between the two switches: You wouldn't use a crossover cable *with* a router between the switches. The router acts as an intermediary and handles the signal routing. Routers typically use straight-through cables to connect to switches. In summary: When you directly connect two switches, they need a crossover cable to make sure the transmit (talking) and receive (listening) lines are properly matched.