1.
Which of the following devices enables
two computers to communicate when they are using different protocols at
each layer of the Open Systems Interconnection (OSI) reference model?
Correct Answer
D. A gateway
Explanation
A gateway is a device that enables two computers to communicate when they are using different protocols at each layer of the OSI reference model. It acts as a translator, converting the protocols used by one computer into the protocols understood by the other computer. This allows for seamless communication between the two devices, even if they are using different protocols at different layers of the OSI model.
2.
Review the following illustration. Station A is sending a message to Station B.If you examined the contents of the
frame as it traveled across Segment 1, what would the source and
destination Media Access Control (MAC) addresses be?
Correct Answer
D. The source MAC address would be AA, and the destination MAC address would be BB.
3.
Which of the following devices enables
two computers to communicate when they are using different protocols at
each layer of the Open Systems Interconnection (OSI) reference model?
Correct Answer
D. A gateway
Explanation
A gateway enables two devices using different protocols to communicate by performing translation and conversion services for them. An example of this is the Gateway Service for NetWare product included in Microsoft Windows 2000 Server, which allows Windows clients to access Internetwork Packet Exchange (IPX)–based Novell NetWare servers without having to run a NetWare client or the IPX protocol themselves.
4.
Review the following illustration. Station A is sending a message to Station B.If you examined the contents of the
frame as it traveled across Segment 1, what would the source and
destination Media Access Control (MAC) addresses be?
Correct Answer
D. The source MAC address would be AA, and the destination MAC address would be BB.
Explanation
If you examined the addresses of a frame sent by Station A on Segment 1, the source MAC address would be AA, and the destination MAC address would be BB, Station B’s MAC address. This is the case because switches do not change MAC addresses as they forward frames. End hosts do not include the address of the switch when they send frames. Bridges and switches are transparent on the network.
5.
You have been hired by a company to
redesign its local area network (LAN). Right now it has a single
10-Mbps Ethernet LAN with 40 users and two shared servers, all
connected through three hubs. Users on the network must share files
with one another and also access the shared servers to retrieve and
store files. Users are complaining that the network is too slow.
Management states that cost is a factor that must be considered. What
would you implement in this situation?
Correct Answer
C. Replace the hubs with switches to define separate collision domains and filter unnecessary traffic from each segment.
Explanation
In this situation, the best choice is to replace the hubs with switches, because the network is relatively small and cost is an issue. In addition, all users must be able to share information directly with one another and to access the servers. On the existing network, all users share the same 10-Mbps communication channel, and each computer must take turns transmitting. By replacing the hubs with switches, you provide each computer with a dedicated 10-Mbps connection to the switch, while reducing unnecessary traffic and collisions on the network. There is no such thing as a dedicated hub. Splitting the network into two routed LANs with 20 users each is not the best solution, because all users must share information on a constant basis. Also, cost is a factor, and routers are more expensive than switches. Replacing the hubs with a Layer 3 switch and defining two VLANS with 20 users each is not a reasonable solution because Layer 3 switches are very expensive. Layer 3 switches and VLANS are typically used in larger enterprise networks.
6.
Which of the following statements about bridges and switches is true?
Correct Answer
B. They are data-link layer devices that use Media Access Control (MAC) addresses to forward frames.
Explanation
Bridges and switches are data-link layer devices that forward frames based on the destination MAC address contained in the frame. They operate in promiscuous mode, listening and processing all frames on each segment, and they build forwarding tables with this information. Forwarding tables are built based on source MAC addresses. Bridges are protocol independent. They do not care what upper layer protocols are being carried on the LAN. Broadcast domains are defined by network layer devices, not data-link layer devices.
7.
Review the following illustration. How many collision domains and broadcast domains exist in the network diagram?
Correct Answer
A. There are three collision domains and three broadcast domains.
Explanation
Each port on a router defines a separate collision domain. Also, routers do not forward broadcasts. Therefore, each network segment represents a separate collision and broadcast domain.
8.
Review the following illustration. Station A is sending a message to Station B across a router.If you examined the contents of the
frame as it traveled across Segment 2, what would the source and
destination Media Access Control (MAC) addresses be?
Correct Answer
C. The source MAC address would be 22 and the destination MAC address would be BB.
Explanation
If you examined the addresses of a frame sent by Station A to Station B as it traveled across Segment 2, the source MAC address would be 22 (the router), and the destination MAC address would be BB, Station B’s MAC address. This is the case because routers change MAC addresses as they forward frames. When the router receives the frame from Station A, it repackages the frame with its own MAC address as the source before forwarding it on to Segment 2.
9.
Which of the following features can
network interface adapters use to automatically configure themselves to
run at an agreed-upon speed and duplex mode?
Correct Answer
C. Autonegotiation
Explanation
Interface adapters that support the autonegotiation feature can automatically configure themselves to function at an agreed-upon speed (10 Mbps, 100 Mbps, or 1000 Mbps) and duplex mode (half-duplex or full-duplex). Successful negotiation of speed requires both adapters to support this feature and the speed being negotiated. There are no features called link negotiation, speed negotiation, or MAC negotiation.
10.
Which of the following statements about hubs is not true?
Correct Answer
A. They are data-link layer devices that connect network devices in a star or ring topology.
Explanation
Hubs (or concentrators) are physical layer devices that amplify and repeat signals out all ports except the one it was received through, regardless of the destination. Hubs are used to connect end systems physically to either a star or ring topology, depending on the data-link layer protocol implemented. Hubs provide an internal crossover circuit connection. Uplink ports are used to extend the distance of a star network, forming a hierarchical star. An example of a hub in a Token Ring network is a MAU. MAUs are connected by RI and RO ports to form a larger ring.
11.
Which of the following statements about full-duplex communication is not true?
Correct Answer
B. Only the transmitting device must support full-duplex communication.
Explanation
Devices that implement full-duplex communication use separate, dedicated transmit and receive channels, which in effect double the available bandwidth. All devices attached to a full-duplex segment must support full-duplex communication. Full-duplex disables the CSMA/CD function and is not subject to collisions.
12.
What is the main function of the Media Access Control (MAC) mechanism?
Correct Answer
D. To regulate access to the network medium
Explanation
Media access and control is implemented through data-link layer mechanisms such as Ethernet’s Carrier Sense Multiple Access with Collision Detection (CSMA/CD) and Token Ring’s token passing. Each of these mechanisms controls or regulates how a device accesses, transmits, and releases a channel. All the other options are either not related to MAC or are not true.
13.
Which of the following statements best describes the bus mastering feature?
Correct Answer
D. It offloads processor cycles by taking over the bus arbitration process when data is being transferred from system memory to a network interface card (NIC).
Explanation
Bus mastering devices can take over tasks normally performed by the processor. Network interfaces that support this feature can bypass the processor when they want to transfer information from system memory. All the other options are either not related to bus mastering or are not true.
14.
In the 100Base-X or Fast Ethernet
specification, what function of the fast link pulse (FLP) signals sent
by hubs and network interface adapters is not provided by the normal
link pulse (NLP) signals used by standard Ethernet?
Correct Answer
B. To advertise the capabilities of the interface adapters and negotiate the speed and duplex mode of the link
Explanation
Network interface adapters and hubs that adhere to the 100Base-X or Fast Ethernet specification use the FLP signaling feature to negotiate the speed and duplex mode to be used for communication. FLP and NLP both verify the integrity of the link. Both the hub and the end device send an FLP signal to the opposite device along their transmit circuit. Negotiation does not work if one side does not support this feature or is configured not to negotiate capabilities. MAC layer mechanisms are not negotiable. Bad frames are detected through a cyclical redundancy check (CRC) calculation and are not a function of the FLP.
15.
On Microsoft Windows operating systems
(Windows 95 and later), what is the primary tool that you use to manage
and configure a network interface adapter, and where is it located?
Correct Answer
B. The Device Manager utility, accessed from the System Properties dialog box in Control Panel
Explanation
The primary tool for managing and configuring network interface adapters and other hardware components is the Device Manager utility, which is accessed from the System Properties dialog box in Control Panel. All the other options either do not exist or are not the primary network interface adapter configuration tool.
16.
What communication method does not allow for the simultaneous transmission and reception of data and is subject to collisions?
Correct Answer
A. Half-duplex
Explanation
Half-duplex communication does not allow simultaneous transmission and reception. Devices take turns transmitting. When multiple devices transmit simultaneously, a collision occurs. Full-duplex communication requires separate, dedicated transmit and receive channels, so it enables the simultaneous transmission and reception of data and is not subject to collisions. There is no communication method called biplex or dual channel.
17.
Which of the following protocols do enterprise networks use to track the performance of critical network components?
Correct Answer
D. SNMP
Explanation
Enterprise networks typically use the Simple Network Management Protocol (SNMP) to monitor performance of critical devices such as routers and switches. SNMP consists of two main components, a management console and agents. The SNMP management component queries SNMP agents within network devices about their status configuration, performance, and error statistics, among other things. Simple Mail Transfer Protocol (SMTP) is an e-mail protocol. There are no protocols called MGMP or SMGP.
18.
Which communication method requires separate channels for simultaneously transmitting and receiving data without collisions?
Correct Answer
B. Full-duplex
Explanation
Full-duplex communication requires separate, dedicated transmit and receive channels. Full-duplex enables the simultaneous transmission and reception of data and is not subject to collisions. Half-duplex communication does not allow simultaneous transmission and reception. There is no communication method called biplex or dual channel.
19.
Which of the following switch types immediately forwards frames after looking at only the destination address?
Correct Answer
A. Cut-through
Explanation
Cut-through switches are fast because they look at only the first six bytes (or destination Media Access Control, or MAC, address) when forwarding a frame. They do not take in the entire frame and perform a cyclical redundancy check (CRC) on its contents prior to forwarding it out a port leading to the destination. Source route is a bridging technique in which the source host, not the switch, determines the path a frame will take through a network to reach a destination. Store-and-forward switches take in the entire frame and verify its contents by performing a CRC calculation before forwarding it. There is no switch called a destination switch.