Network Devices Hubs, Switches, Routers

Network Devices A LAN can refers to a Broadcast Domain / a Subnet LAN traffic congestion is caused by Too many hosts in a broadcast domain Excessive broadcasts Multicasting Low / insufficient bandwidth To solve this we can segment the network • • • • •

Hubs and Repeaters Layer 1 of the OSI The physical layer (moving bits on physical media) Hubs repeat signals received on each port by broadcasting to all the other  connected ports. Repeaters used to connect two or more Ethernet segments of any media type, and to provide signal amplification for a segment to be extended. Ethernet is subject to the "5-4-3" rule regarding repeater placement, meaning we can only have five segments connected using four repeaters with only three segments capable of accommodating hosts .

Bridges and Switches Layer 2 of the OSI The data link layer (based layer  (based on the Ethernet packet / mac address) Bridges used to connect different networks types cannot filter out broadcast traffic

Bridges segment collision domains. Only 2 networks can be linked with a bridge. Bridges are layer 2 devices (Data Link layer) which are usually used to segment a LAN into two segments. Bridges examine frames, keeping local traffic local, and forwarding any non-local traffic. Each port on a bridge is a separate collision domain i.e. ports A, B, C here. Important points to remember about bridges: each segment connected to a bridge is in a separate collision domain; all segments on a bridge are in the same broadcast domain; and bridges forward all broadcast messages.

A Collision Domain A collision domain is any area where a collision can theoretically take place, so only one device can transmit at a time in a collision domain.

Switches breakup collision domains, each port on a switch represents a collision domain. Most cannot filter out broadcast traffic. 3 main switching methods are 1. Cut Through Through - looks looks at the first 6 bytes bytes of the the destination destination MAC address address only 2. Fragmen Fragmentt free cut cut through through - looks looks at the the first 64 64 bytes bytes only 3. Store Store and forwa forward rd - looks looks at the the entire entire frame frame

Routers Layer 3 of the OSI The network layer (logical ip addressing) Routers do not forward broadcast traffic they perform packet switching / filtering by determining the most efficient path for a packet to take sending packets around failed segments. Routers also connect remote networks providing internetwork communication. communication . Routers break-up a broadcast domain and collision domains as they don’t forward broadcasts by default.

Question

Refer to the exhibit. How many broadcast domains are there in the topology shown, assuming that VLANs are not configured on the switches? A. one B. two C. three D. four  E. six F. eight Answer B Two Note the trick question, says broadcast domains therefore answer is 2 not 8

Gateways enable communications between different protocols, data types and environments. Gateways operate at all layers of the OSI model without making any forwarding decisions. A router that provides the connection between a lan and the internet is the default gateway. In this situation the layer 3 router operates at layer 4 the

transport layer (tcp/udp) as it forwards protocols directly to specific network devices ie web/email server.

Question The Sales and Production networks are separated by a router, which of the following statements most accurately describes the characteristics of the network’s broadcast and collision domains.

A. There are two broadcast domains in the network B. There are four broadcast domains inn the network C. There are six broadcast domains in the network D. There are four collision domains in the network E. There are five collision domains in the network F. There are seven collision domains in the network

Answer A, F Explanation We have a hub in the sales department and a switch in the production department. Therefore we have two broadcast domains one for each network separated by a router. For collision domains we have 5 pcs and one port for e1 so we have 6 collision domains on the switch side of things plus one more for the hub side total = 7.

Exam Questions Question At Layer 2 of the OSI model, which component connects a host to the network media? A. Hub B. Switch C. Bridge D. NIC E. Transceiver  Answer D Explanation The data link layer is layer 2 of the OSI model. The data link layer involves frames and uses the burned in MAC addresses that NIC cards and router interfaces have. Incorrect Answers A. A hub operates at the physical layer, layer 1. B. Switches operate the Data Link layer, layer 2, of the OSI model. However, they are not used to connect hosts to the network media. C. Bridges operate the Data Link layer, layer 2, of the OSI model. However, they are used to connect network segments, not to connect hosts to the network media. E. A transceiver works at the physical layer, layer 1.

Question Study the network topology exhibit carefully, in particular the two switches SW1, SW2, and the router RT3. Which statements are true in this scenario? (Select two)

A. The hosts on the 192.168.1.0 network form one collision domain and the hosts on the 192.168.2.0 network form a second collision domain. B. Each host is in a separate collision domain. C. All the devices in both networks will receive a broadcast to 255.255.255.255 sent by host A. D. Only the devices in network 192.168.1.0 will receive a broadcast to 255.255.255.255 sent by host A. E. All the devices on both networks are members of the same collision domain. Answer B & D Each host is in a separate collision domain.

Only the devices in network 192.168.1.0 will receive a broadcast to 255.255.255.255 sent by host A. Question Which of the following describe router functions? (Choose three) A. Packet switching B. Collision prevention on a LAN segment C. Packet filtering D. Broadcast domain enlargement E. Broadcast forwarding F. Internetwork communication Answer A, C, F Explanation A. Router works in Layer 3 in OSI Model. Packet switching is function of OSI Layer 3. C. In Packet switching process, packet will be filtered at a particular physical Interface during packet switching. F. In OSI Model each layer dependent on the layer be low and above layer for Internetwork communication. Here Router works with Data Link layer and Transport layer. Incorrect answers A. Collision will occur on physical layer. It is not related to Router  D, E. Broadcast activity is not the function of Router. Router will not transmit Broadcast information out to another router.

Question Which of the following contribute to congestion on an Ethernet network. (Choose two) A. Use of full duplex mode. B. Creation of new collision domain. C. Creation of new b roadcast domain. D. Addition of hub to the network. E. Use of switches in the network. F. Amount of ARP or IPX SAP traffic. Answer D, F The Addition of hub to the network and the a mount of ARP or IPX SAP traffic. Explanation D. Hub works on Half duplex mode. If more devices connect to a hub and sending simultaneously collision will occur .It contributes to congestion. F. ARP also creates congestion in the network Incorrect answers A. Full Duplex will not generate congestion in the network. B. Creation of new collision domain means connecting a switch instead of Hub will not contribute congestion. Switch isolates collision domain. C. Creation of VLAN’s in a switch isolate broadcast domain. Each Vlan is separate broadcast domain. It will not generate congestion in network.

Question What feature of a networks switch allows an administrative to create separate broadcast domains? A. Store-and-forward switching B. Microsegmentation C. Transparent bridging D. Fragment-free switching E. Virtual LANs F. Cut-through switching

Answer E Explanation Creation of VLAN in a switch provide separate Broadcast domain. If VLAN is not there all ports as members of one Broadcast domain. Incorrect Answers A. This is one of the Switching method in a switch. It will not play any role for creating separate broadcast domains B. Not related to the question C. Transparent bridging is called Transparent because the endpoints devices do not need to know that the bridges exists. It will not play any role for creating separate broadcast domain

Question Which statement describes the rule of split horizon? A. Only routers can split boundaries (horizons) between concentric networks. B. All distance vector protocols require fall back routers that may cause momentary loops as the topology changes. C. Networks can only remain fully converged if all information about routers is sent out all active interfaces. D. Information about a route should not be sent back in the direction from which the original update came. E. Each AS must keep routing tables converged to prevent dead routes from being advertised across the AS boundary. Answer D Information about a route should not be sent back in the direction from which the original update came. Explanation Split horizon includes two related concepts that affect what routes are included in a routing update An update does not include the subnet of the interface out which the update is sent All routes with outgoing interface of interface x are not included in updates sent out that same interface x. Incorrect Answers A. There is no such requirement B. Distance vector protocols updates routing table at regular intervals instead of Topology changes C. This is not a feature of split horizon E. This is not a related feature for split horizon

Question Your trainee, asks you about basic characteristics of switches and hubs for network connectivity. What should you tell him? A. Switches take less time to process frames than hubs take. B. Switches do not forward b roadcasts. C. Hubs can filter frames. D. Using hubs can increase the amount of bandwidth available to hosts. E. Switches increase the number of collision domains in the network. Answer E Explanation Switches use a couple of different types of internal processing variations. Almost of the more recently released switches use store-and-forward processing, but all three types of switching are supported in at least one type of currently available Cisco Switch. Store-and-forward – The switch fully receives all bits in the frame (store) before forwarding the frame (forward). Cut-through – The switch performs the address table lookup as soon as the destination address field in the header is received. Fragment-free – This performs like cut-through switching, but the switch waits for 64 bytes to be received before forwarding the first bytes of the outgoing frame.

Question Your boss at asks you why you are using a router to segment the network at the main office. What are the benefits? What should you tell her? (Choose two) A. Filtering can occur based on Layer 3 information. B. Broadcasts are eliminated. C. Routers generally cost less than switches. D. Broadcasts are not forwarded across the router. E. Adding a router to the network decreases latency. Answer A, D

Question You have segmented a network into two separate segments, segment 1 and segment2, with a Cisco router. Your boss at is concerned about the cost, and wants to know what the purpose of  your action is. What should you tell him? A. It increases the number of collisions. B. It decreases the number of broadcast domains. C. It connects segment 1’s broadcasts to segment 2. D. It prevents segment 1’s broadcasts from getting to segment 2. Answer D Question

Which switching method protects network segment bandwidth from errored frames? Answer Store-and-forward Answer Store-and-forward transmits transmits frames only if the frame's integrity is assured. If the switch receives an errored frame, then the switch discards it. Question How does a store-and-forward switch know if a frame is errored? Answer The Answer The switch uses the CRC to determine whether any changes occurred to the frame since the source generated it. The switch calculates CRC for the received frame and compares it with the CRC transmitted with the frame. If they differ, the frame changed during transit and will be discarded in a store-and-forward switch. Question What switching method examines the destination MAC address as the frame is being received and then begins forwarding the frame prior to receiving the entire frame? A. B. C. D.

Modi Modifi fied ed Cut Cut Thr Throu ough gh Stor Store e and and For Forwa ward rd Cut Throu hrough gh Frag Fragme ment nt Free Free

Answer C Cut Through

Question What are good reasons for using layer two switches? (Choose two) A. To reduce collisions. B. To increase collisions. C. To increase the number of collision domains. D. To decrease the number of collision domains. E. To decrease the number of broadcast domains. Answer A, C To reduce collisions and to increase the number of collision domains. Explanation A switch creates multiple collision domains, and reduces the number of nodes in the domain. This results in less contention and interference which in turn reduces the number of collisions. Incorrect Answers B. Switches are design to REDUCE collisions and not increase them. D. When a switch segments a network it increases the number of do main and it does not reduce them. E. A switch can neither increase nor decreases the broadcast domains.

Question How does a layer two device such as a bridge or switch function?

A. It maintains a table of the IP address of the host connected to its internet segment B. It passes packets outside of its network segment if its IP address cannot be found on its table.

C. It looks up the frames destination in its address table and sends the frame towards the destination. D. It maintains the table of the data link layer and network layer addresses for the host connected to its network segment. Answer C Explanation A transparent bridge stores information information in memory in what is called a forwarding forwarding table. The forwarding table lists each end station (from which the bridge has heard a frame within a particular time period) and the segment on which it resides. When a bridge hears a frame on the network, it views the destination address and compares it to the forwarding table to determine whether to filter, flood or copy the frame into another segment. Incorrect Answers A. The forwarding table does not contain contain a list of IP address. Rather it contains a list of devices devices that it is connect to and on which segment each device resides. B. If the destination device is unknown to the bridge, the bridge forwards the frame to all segments except the one on which it was received. This process is known as flooding. D. The device maintains a list of the data link layer addresses for host conne cted to its network segment. Question Your company is concerned about Security on your network. network. Each department has its own file file server and the company also has an enterprise server that is shared by all departments. departments. The accounting department is concerned about the accounting information being accessible from the other departments. What can you as the network administrator use to control the information so that it is not being passed between the departments?

A. Bridge between management and sites. B. Routers to provide the most secure segmentation. C. A hub to provide the ease of management and a satisfactory alternative for the network security. D. An Ethernet switch to secure separation through programming the access list of each port of  the switch.

Answer B Explanation Routers provide better separation, dividing the segments into both separate collision and broadcast domains, and provide access lists for controlling security. Incorrect Answers A, C, D - Are Layer 2 devices, which breaks up the collision domains, but is still one broadcast domain. Security and filtering within these devices are primitive (although switching is a little more advanced). Any filtering that can be done at layer 2 is primitive and requires a lot of administrative effort.

Question Which of the following correctly identifies switched and routed data flow? A. Switches create a single co llision domain and a single broadcast domain. Routers provide separate broadcast domains.

B. Switches create separate collision domains but a single broadcast domain. Routers provide separate broadcast domains. C. Switches create a single collision domain and a separate broadcast domain. Router provides a separate broadcast domain as well. D. Switches create separate collision domains and separate broadcast domains. Routers provide separate collision domains. Answer B Explanation Switches break up the collision domains, but it is still a single broadcast domain. Routers also create separate collision domains, but also separate broadcast domains, as routers usually do not pass broadcast traffic. Incorrect Answers A. Switches create multiple co llision domains. C. Switches maintain one broadcast domain, and separate/multiple collision collision domains. D. Switches maintain one broadcast domain. Question Using a protocol analyzer you determine your LAN traffic is experiencing congestion. congestion. What could be some possible causes for a congested n etwork? (Choose four.) A. Too many hosts in a broadcast domain. B. Full Duplex operation. C. Broadcast storms. D. Multicasting. E. Segmentation. F. Low bandwidth. Answer A, C, D, F Explanation A. Too many hosts in a broadcast domain would cause many collisions and congestion. C. Broadcast storms would have a negative impact on available bandwidth. D. Multicasting targets multiple destinations and requires a lot of bandwidth. F. Low available bandwidth would of course result in a congested network faster than a network with higher bandwidth. Incorrect Answers B. Full duplex operation would decrease congestion. E. Segmentation decreases the collisions domains, the n etwork traffic, and the congestion.

Question What are the benefits of replacing a hub with a bridge and segmenting the network? A. It increases the number of collision domains. B. It decreases the number of collision domains. C. It increases the number of broadcast domains. D. It decreases the number of broadcast domains. Answer A Explanation Bridge networks have the following following characteristics: each segment has its own collision collision domain, all connected devices are part of the same broadcast domain, and all segments must have the same data link layer implementation.

Incorrect Answers. B. When a network is segmented by a bridge the collisions domains increase and not decrease. C and D. The addition of a bridge to a network has no effect on the nu mber of domains. Question Which of the following statements about layer 2 bridges and switches are true? (Choose three.) A. Switches are primarily software based while bridges a re hardware based. B. Both bridges and switches forward Layer 2 broadcasts. C. Bridges are frequently faster than switches. D. Switches have a higher number of ports than most bridges. E. Bridges define broadcast domains while switches define collision domains. F. Both bridges and switches make forwarding decisions based on Layer 2 addresses. Answer B, D, F Explanation Switches and bridges are both Data Link layer devices and make their forwarding decision based on Layer 2 addresses. As a result they they have a number of similar similar attributes. Switches have a higher port density. Incorrect Answers A. Switches are hardware based. C. Switches are most often faster than bridges. E. Both define broadcast domains.

Question What are benefits of bridging (Choose two.) A. To reduce broadcasts within collisions domains. B. To reduce collisions within broadcasts domain. C. To increase the number of broadcasts domains. D. To increase the broadcasts within collisions domains. E. To increase the number of collision domains. F. To increase the efficiency of routing. Answer B, E Explanation B. Bridging reduces the scope of the collision domains. The collision domains are contained within the broadcast domains. E. Bridging increases the number o f collision domains. Incorrect Answers A. As all devices connected to the same bridge are in the same broadcast broadcast domain, all broadcasts are forward to all collisions collisions domains. Therefore broadcasts are not reduced. C. Bridges do not affect the number of broadcast domains. D. Bridges neither increase nor decrease the broadcasts within a collision domain. F. Bridges do not necessarily increase the efficiency of routing. Question Comparing half-duplex Ethernet to full-duplex Ethernet which of the following are true? (Choose two.) A. Shared collision domain. B. Private collision domain. C. Higher effective throughput.

D. Lower effective throughput. E. Private broadcast domain. Answer A, D Explanation Half-duplex Ethernet have a lower effective throughput due to shared collision domain the a fullduplex Ethernet. Incorrect Answers B. The collision domain is shared not private. C. Half-duplex as a lower effective throughput. E. It is a shared collision domain not a private broadcast domain.

Question You are concerned about broadcast traffic in your network. network. You would like to split up your  network into two separate broadcast domains. domains. Which one of the following hardware devices devices can you use? A. Hub B. Router  C. Bridge D. Repeater  Answer B Explanation A router splits the network into subnets. Each subnet is a separate broadcast domain. Incorrect Answers A, D. Hubs and repeaters work at the physical layer. They are not able to reduce either  broadcasts or collisions. C. A bridge splits the network into collision domains. However, a bridge would have no affect on the broadcast domains.

Question An Ethernet switch has many functions. functions. Which of the following are correct functions functions of a Layer 2 Ethernet switch? (Choose two) A. Establishes a single collision domain. B. Establishes multiple collision domains. C. Builds a dynamic MAC address mapping table. D. Maintains a routing table. E. Forwards unicast frames only. Answer B, C Explanation B. Each switch port is a separate collision domain. C. Since switches work at Layer- 2 (some work at Layer 3 a s well) they are able to build a MAC address table. This table improves performance. Incorrect Answers A. A switch separate the network into separate collision domains, on for each port on the switch.

D. Layer-2 switches do not understand layer-3 information. They are not able to build routing tables. E. Switches are able to forward broadcasts. They simple send the signal on all port except the receiving port.

Question You have just been hired to setup a new company network. This company will be using an accounting package that requires multiple hosts. These hosts are the accountants and they must be able to support data transfer between each other at a rate of 10 Mbps. The company will also have a file server that is used for the other employees of the company who just use word processing applications that use less than 3 Mbps to transfer files to server. What is your economical recommendation? A. That the existing 10BaseT hub be replaced with 100BaseT hub to improve overall performance. B. That a router can separate the testing application from the rest of the network thus allowing the testing application more bandwidth. C. That the switch be installed so that enterprise server can be provided a 100 Mbps port and each of the testing application hosts can be given dedicated 10 Mbps ports. D. That a bridge be placed between the enterprise server and all other users with the exception of  the testing application. Answer C Explanation: With buffering in the switch, the enterprise server can serve multiple hosts at almost full capacity, since the 100Mbps port will be faster than the rest of the users totaled as a whole. Incorrect Answers A. This would require all NICs to be upgraded, and result in a large collision domain with possible poor performance. B. A router would become a bottleneck, and not allow efficient performance. D. A bridge would be a bottleneck, and not be able to provide the necessary performance and throughput. Question Using your protocol analyzer you have determined your network is very congested. Currently all the devices are connected through a hub. Which solution would best decrease congestion on the network? A. Add a second hub. B. Replace the hub with a router. C. Replace the hub with a switch. D. Replace the hub with a repeater. Answer C Explanation A switch would eliminate the collision domains and thus increasing speed. A router would break each segment into their own collision domains and broadcast domains. This would reduce network congestion the most. Incorrect Answers A. There will still be one collision domain which would mean that the network would still be congested.

B. A router can be used to segment the network into subnets. However, this would require further  adjustments: the subnets must be created. Furthermore, a switch is faster than a router and a single hub needs to be replaced. D. A repeater does not affect congestion.

Question Which of the following is a Layer 2 device? A. Hub B. Router  C. Switch D. Repeater  Answer C Explanation Switches and Bridges run on Layer 2. Incorrect Answers A and D. They are Layer 1 Physical Layer devices. B. Routers are layer 3 device. Question You are trying to convince your boss to switch from from a hub to a Cisco switch. You have explained to your boss that you will have fewer collisions with the Cisco switch because you will be using full-duplex. Your boss responds with how many collisions collisions are caused by transmitting and receiving frames simultaneously in full-duplex mode. What should your response be? A. One B. Two C. None D. Several Answer C Explanation Full Duplex requires one and only one device to be hooked up to a switch port, and each switch port is a separate collision domain. Since there is no contention (the node has exclusive control of  the segment) there are no collisions. Incorrect Answers A, B and D: It is impossible for collision to occur within a full duplex network.

Question What are two benefits of segmenting a network with a later 2 bridge? (Choose two) A. To reduce collisions. B. To increase collisions. C. To add collision domains. D. To reduce collision domains. E. To have more broadcast domains. Answer A, C Explanation When you segment a network with a bridge you are reducing the number of collisions by creating another collision domain. Incorrect Answers

B. A bridge decreases collisions, not increases collisions. D. Collision domains are increased, not decreased. E. There is still one and only one broadcast domain. Question Which of the following correctly compares Fast Ethernet to Ethernet? (Choose four.)

A. Fast Ethernet uses the Same Maximum Transmission Unit (MTU). B. Fast Ethernet is based on an extension to the IEEE 802.3 specification. specification. C. Fast Ethernet uses the same Media Access control (MAC mechanisms). D. Fast Ethernet preserves the frame format that is used by Ethernet. E. Fast Ethernet offers a speed increase one hundred times that of the Ethernet. Answer A, B, C, D Explanation Fast Ethernet shares a great deal of similarities similarities with Ethernet. Ethernet. These similarities similarities are the same MTU, same MAC mechanism mechanism and frame format. Fast Ethernet is based on IEEE IEEE 802.3u, which is an extension to IEEE 802.3. Incorrect Answers E. Its speed is 10 times faster, not 100 times. Question Which two statements about a Layer 2 bridge are true? (Choose two) A. A bridge floods multicasts. B. A bridge floods broadcasts. C. A bridge does not flood multicasts. D. A bridge does not flood broadcasts. Answer A, B Explanation A bridge must send all multicasts and broadcast to all ports, since there is only one broadcast domain. Incorrect Answers C and D. Because a bridge DOES flood broadcasts and multicasts Question Which one of the following is not a characteristic of a network segment on a transparent switch? A. The segment has its own collision domain. B. The segment can translate from one media to a different media. C. All devices in the segment are part of the same b roadcast domain. D. One device per segment can currently send frames to the switch. Answer B Explanation A switch is usually only handle one media type at a time. Incorrect Answers A, C and D. The statements are characteristics of a network segment on a switch. Question Which two statements are true about half duplex and full duplex? (Choose two) A. Ethernet 802.3 utilizes a half duplex method for data transfer.

B. In a 100mbps point to point connect, a full duplex connection can provide 400mbs of data transfer. C. Ethernet switches can use the full duplex mode to connect multiple nodes on a single port office switch. D. Full duplex Ethernet takes advantage of UTP using one pair of transmission and other pair for  reception. Answer A, D Explanation Half duplex Ethernet is most often found in a 802.3 network and full duplex a chieves data transmission by using one pair to receive data and another to send data. Incorrect Answers In full duplex you can maximize up to double; by transmitting and receiving at the same time, for a nominal maximum throughput of 200mbps. C. When running full duplex, only one device can be attached to the port. Question Which connections allow the use of full-duplex Ethernet? (Choose three) A. Switch to host B. Switch to switch C. Hub to hub D. Switch to hub E. Host to host

Answer A, B, E Explanation Host and Switch works in full duplex mode. Incorrect answers C, D: Hub Operates in half duplex mode. So connection from Hub to hub or Hub to switch works in half duplex mode.

Question What is a disadvantage to using bridges in your network? A. B. C. D.

Filt Filter ers s by MAC MAC addr address ess Stops Stops bro broad adca cast st sto storm rms s Doesn' Doesn'tt stop stop broa broadca dcast st stor storms ms Can only only use up up to 4 brid bridges ges in in any LAN LAN

Answer C Explanation Even though the 5-4-3 rule specifies you can only h ave 4 bridges in a network, that is not really a disadvantage. The disadvantage to bridging is that it filters by MAC address and cannot create separate networks like a router can. This means that if a broadcast storm was to take place a bridge will forward the frames.

Question

Answer B, E

Question The LAN needs are expanding at the corporate office, which is quickly growing. You are instructed to enlarge the area covered by a single L AN segment on the network. Which of the following are layer 1 devices that you can use? (Choose all that apply.) A. A switch. B. A router. C. A network adapter card. D. A hub. E. A repeater.

Answer D, E Explanation A hub simply repeats the electrical signal and makes no attempt to interpret the electrical signal (layer 1) as a LAN frame (Layer 2). So, a hub actually performs OSI layer 1 functions, repeating an electrical signal, whereas a switch performs OSI layer 2 functions, actually interpreting Ethernet header information, particularly addresses, to make forwarding decisions. Hubs can be used to increase the number of stations that can be supported on a LAN. Because the repeater does not interpret what the bits mean, but does examine and generate electrical signals, a repeater is considered to operate at Layer 1. Repeaters can be used to physically extend the LAN to greater distances.

Question You are experiencing intermittent issues relating to congestion with your network. What are the possible causes of congestion on a LAN? (Choose all that apply)

A. A broadcast domain with too many hosts. B. Full duplex operation. C. Broadcast storms. D. Multicasting. E. Network Segmentation. F. Low bandwidth. Answer A, C, F Explanation: A LAN segment with too many hosts can mean that there are a large number of  stations contending for bandwidth. It can also mean an increase in the number of collisions on the segment, which can cause further congestion issues. Broadcast storms are the result of a large number of broadcasts sent over the LAN. Because each station listens to these broadcast messages, congestion can occur quickly. Finally, low bandwidth can simply mean that the LAN can not process all of the LAN traffic that is being sent. This can mean that TCP sessions are retransmitted, which can lead to additional congestion. Incorrect Answers B. This can alleviate congestion, as data can be sent and received at the same time. In addition, collisions are not possible in a full duplex LAN. D. Multicasting can actually alleviate congestion issues, as single streams of information can reach multiple hosts at the same time, instead of using a series of po int to point connections. E. Segmentation breaks up a large LAN into multiple, smaller LANS. This will mean fewer hosts per broadcast domain.

Question Which type of cable should be used to make a connection between the Fa0/0 port on a router and the Fa0/0 port switch? A. Rollover cable B. Console cable C. Crossover cable D. Straight-through cable E. Serial cable Answer D Explanation

Straight-through cables are used to connect host to switch (or hub) and router to switch (or hub). Question What components are required to directly connect two PCs so they are able to participate in a simple peer-to-per network? Choose three A. Straight-through cable B. Compatible network interfaces C. Networking protocol D. Hub E. Crossover cable F. router  Answer B, C, E Explanation: This cable can be used to directly connect two computers to each other without the use of a hub o r switch. Crossover cables are terminated with CAT 5 RJ-45 (RJ stands for  "Registered Jack") modular plugs. RJ-45 plugs are similar to those you'll see on the end of your  telephone cable except they have eight versus four contacts on the end of the plug. Also, make sure the ends you select are rated for CAT 5 wiring.

Question What kind of cable should be used to establish a trunked line between two Catalyst 2950 switches? A. A straight-through cable B. An EIA/TIA-232 serial cable C. An auxiliary cable D. A modem cable E. A cross-over cable Answer E Explanation A crossover cable is used to connect two of the same device types, or devices from the same OSI layer.

Question

What kind of cable should be used to make each connection that is identified by the numbers shown? A. 1- Ethernet crossover cable 2-Etherenet straight-through cable 3- fiber optic cable 4- rollover  cable B. 1- Ethernet rollover cable 2-Etherenet crossover cab le 3- serial cable 4- rollover cable C. 1- Ethernet rollover cable 2-Etherenet crossover cable 3- serial cable 4- null modem cable D. 1- Ethernet straight-through cable 2-Etherenet crossover cable 3- serial cable 4- rollover cable E. 1- Ethernet straight-through cable 2-Etherenet crossover cable 3- serial cable 4- Ethernet straight-through cable F. 1- Ethernet straight-through cable 2-Etherenet straight-through cable 3- serial cable 4- rollover  cable Answer F Explanation In the diagram one host is connect to a switch using a straight through cable. The switch is connected to a router using a straight through cable while router to router connections are made using a serial cable. One PC configures the router connects using a rollover cable, as well as a computer connected to the router's Ethernet port using a crossover cable.

Question

The two T Lab routers shown are interconnected with back-to-back cables between their serial interfaces. How should the serial interface of the R1 router be configured to establish Layer 3 connectivity between the two routers? A. R1(config)#interface serial 3 R1(config-if)# clock rate 64000

R1(config-if)# no shutdown B. R1(config)#interface serial 3 R1(config-if)# ip address 192.168.10.3 255.255.255.0 R1(config-if)# clock rate 64000 C. R1(config)#interface serial 3 R1(config-if)# ip address 192.168.10.3 255.255.255.0 R1(config-if)# clock rate 64000 R1(config-if)# no shutdown D. R1(config)#interface serial 3 R1(config-if)# ip address 192.168.10.3 255.255.255.0 R1(config-if)# no shutdown

Answer D Explanation: When examining the interface using the show controllers command, the DTE cable is connected so there is no n eed to specify the clock rate and bandwidth; just specify the IP address and bring up the interface. Only the DCE side of the serial to serial connection is required to specify the clock rate.

Question For security reasons, the network administrator needs to prevent pings into the corporate networks from hosts outside the internetwork. Which protocol should be blocked with access control lists? A. UDP B. ICMP C. IP D. TCP Answer B Explanation: ICMP is used for error and control messages within the IP world and is very much integrated with IP. Ping is a computer network tool used to test whether a particular host is reachable across an IP network. Ping works by sending ICMP "echo request" packets to the target host and listening for ICMP "echo response" replies. Question Which statements describe features of full-duplex Ethernet? (Choose three.) A. allows packets to be received and sent simultaneously by a host B. requires a minimum of two wires C. reduces the number of collisions

D. allocates between 60 and 80 percent of available bandwidth in both directions E. allocates 100 percent of the bandwidth in both directions F. increases the number of broadcast domains

Answer A, C, E