CCNA Exam 640-802 (Part 1) Practice Test
This is a CCNA EXAM 640-802 (Part 1) Practice Test. For those in the business of information technology, the Cisco Certified Network Associate (CCNA) is an important certification that gives you a firm understanding of fundamental networking principles and the ability to design your networks using a wide range of equipment. Do you know enough to pass the exams already?
Questions and Answers
- 1.
Both switches and hubs are being utilized within the Certkiller network. Which of the following is true regarding the use of switches and hubs for network connectivity in this network?
- A.
A. Switches take less time to process frames than hubs take
- B.
B. Hubs can filter frames
- C.
C. Switches do not forward broadcasts
- D.
D. Switches increase the number of collision domains in the network
- E.
E. Using hubs can increase the amount of bandwidth available to hosts
Correct Answer
D. D. Switches increase the number of collision domains in the networkExplanation
Switches increase the number of collision domains in the network. This means that each port on a switch is its own collision domain, whereas with hubs, all ports are in the same collision domain. By dividing the network into multiple collision domains, switches can reduce the chances of collisions occurring and improve network performance.Rate this question:
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- 2.
Which one of the following characteristics is true regarding the use of hubs and switches?
- A.
Hubs can have their ports be configured with VLANs
- B.
Using hubs is costly with regard to bandwidth availability.
- C.
Switches can not forward broadcasts.
- D.
Switches are more efficient than hubs in processing frames.
- E.
Switches increase the number of collision domains in the network.
Correct Answer
E. Switches increase the number of collision domains in the network.Explanation
Switches increases the number of collisions domains in the network. Switches that are configured with VLANs will reduce the size of the collision domains by increasing the number of collision domains in a network, but making them smaller than that of one big, flat network.Rate this question:
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- 3.
When comparing and contrasting the similarities and differences between bridges and switches, which of the following are valid statements? Choose all the valid answer choices)
- A.
Bridges are faster than switches because they have fewer ports.
- B.
A switch is a multiport bridge,
- C.
Bridges and switches learn MAC addresses by examining the source MAC address of each frame received.
- D.
A bridge will forward a broadcast but a switch will not.
- E.
Bridges and switches increase the size of a collision domain.
Correct Answer(s)
B. A switch is a multiport bridge,
C. Bridges and switches learn MAC addresses by examining the source MAC address of each frame received.Explanation
Both bridges and switches build the bridge table by listening to incoming frames and examining the source MAC address in the frame. Switches are multiport bridges that allow you to create multiple broadcast domains. Each broadcast domain is like a distinct virtual bridge within a switch.Rate this question:
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- 4.
Which of the following correctly describe the various functions and virtues of a router? (Select all valid answer choices)
- A.
Packet switching
- B.
Collision prevention on a LAN segment.
- C.
Packet filtering
- D.
Broadcast domain enlargement
- E.
Internetwork communication
Correct Answer(s)
A. Packet switching
C. Packet filtering
E. Internetwork communicationExplanation
The main function of a router is to connect different, separated networks together. In doing so, switching packets from one network to another is a primary function, along with providing for communication between networks. As an additional feature, routers are capable of providing filtering on a network address and application port level, so choice C is also correct.Rate this question:
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- 5.
The LAN needs are expanding at the Certkiller corporate office, which is quickly growing. You are instructed to enlarge the area covered by a single LAN segment on the Certkiller 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
Correct Answer(s)
D. A hub
E. A repeaterExplanation
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.Rate this question:
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- 6.
Cisco is the leader in the router market space. What basic functions do their routers perform in a network? (Choose two)
- A.
The microsegmentation of broadcast domains
- B.
Path selection
- C.
Packet switching
- D.
Bridging between LAN segments
- E.
VLAN membership assignment
Correct Answer(s)
B. Path selection
C. Packet switchingExplanation
The primary functions of a router are: Packet Switching and Path Selection. It is the routers job to determine the best method for delivering the data, and switching that data as quickly as possible.Rate this question:
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- 7.
Both bridges are switches are being used throughout the Certkiller LAN. Which of the following statements are true regarding bridges and switches in this network? (Choose 3)
- A.
Switches are primarily software based while bridges are hardware based.
- B.
Switches usually have a higher number of ports than most bridges.
- C.
Bridges are frequently faster than switches.
- D.
Both bridges and switches forward Layer 2 broadcasts.
- E.
Both bridges and switches make forwarding decisions based on Layer 2 addresses.
Correct Answer(s)
B. Switches usually have a higher number of ports than most bridges.
D. Both bridges and switches forward Layer 2 broadcasts.
E. Both bridges and switches make forwarding decisions based on Layer 2 addresses.Explanation
Switches usually have a higher number of ports than most bridges because switches are designed to connect multiple devices within a LAN, so they need to support more connections. Both bridges and switches forward Layer 2 broadcasts because they operate at the data link layer of the OSI model, which includes the handling of broadcast traffic. Both bridges and switches make forwarding decisions based on Layer 2 addresses because they use MAC addresses to determine where to forward data packets within the network.Rate this question:
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- 8.
As a network administrator, you will need to decide on the appropriate network devices to use. Which of the following correctly describes the roles of devices in a WAN? (Choose three)
- A.
A CSU/DSU terminates a digital local loop.
- B.
A router is commonly considered a DCE device.
- C.
A modem terminates an analog local loop.
- D.
A router is commonly considered a DTE device.
- E.
A modem terminates a digital local loop.
Correct Answer(s)
A. A CSU/DSU terminates a digital local loop.
C. A modem terminates an analog local loop.
D. A router is commonly considered a DTE device.Explanation
A CSU/DSU terminates a digital local loop. This means that it connects the customer's equipment to the service provider's network by converting the digital signals from the customer's equipment into a format that can be transmitted over the digital local loop.
A modem terminates an analog local loop. This means that it connects the customer's equipment to the service provider's network by converting the analog signals from the customer's equipment into a format that can be transmitted over the analog local loop.
A router is commonly considered a DTE device. DTE stands for Data Terminal Equipment, and a router is a device that connects multiple networks together and directs traffic between them. It is commonly considered a DTE device because it is the endpoint of a communication circuit.
In summary, a CSU/DSU terminates a digital local loop, a modem terminates an analog local loop, and a router is commonly considered a DTE device.Rate this question:
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- 9.
The Certkiller network administrator needs to determine what LAN devices to install on the Certkiller network. What are two advantages of using Layer 2 Ethernet switches over hubs? (Choose two)
- A.
Allowing simultaneous frame transmissions
- B.
Increasing the size of broadcast domains
- C.
Increasing the maximum length of UTP cabling between devices
- D.
Filtering frames based on MAC addresses
- E.
Decreasing the number of collision domains
Correct Answer(s)
A. Allowing simultaneous frame transmissions
D. Filtering frames based on MAC addressesExplanation
A: A half duplex connection is where only one device can send or receive at a time. A full duplex connection is where both devices can send and receive at the same time. Thus, if you have a 100Mb half-duplex connection, only sending at 100Mb OR receiving at 100Mb can happen at the same time. If you have a 100Mb full duplex connection, you can effectively get 200Mb out of the link because you could be sending 100Mb and receiving 100Mb at the same time. D: Switches are capable of filtering frames based on any Layer 2 fields. For example, a switch can be programmed to reject (not forward) all frames sourced from a particular network. Because link layer information often includes a reference to an upper-layer protocol, switches usually can filter on this parameter. Furthermore, filters can be helpful in dealing with unnecessary broadcast and multicast packets.Rate this question:
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- 10.
CDP is being used throughout the Certkiller network. What are two reasons why the Certkiller network administrator would use CDP? (Choose two)
- A.
To determine the status of network services on a remote device
- B.
To obtain the IP Address of a connected device in order to telnet to the device
- C.
To verify the type of cable interconnecting two devices
- D.
To verify Layer 2 connectivity between two devices when Layer 3 fails
- E.
To obtain VLAN information from directly connected switches
Correct Answer(s)
B. To obtain the IP Address of a connected device in order to telnet to the device
D. To verify Layer 2 connectivity between two devices when Layer 3 failsExplanation
CDP (Cisco Discovery Protocol) is a Cisco proprietary protocol used to gather information about directly connected Cisco devices. By using CDP, the Certkiller network administrator can obtain the IP Address of a connected device in order to telnet to it, allowing for remote management and configuration. Additionally, CDP can be used to verify Layer 2 connectivity between two devices when Layer 3 fails, helping to troubleshoot and diagnose network connectivity issues.Rate this question:
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- 11.
CDP is running between two Certkiller devices. What information is supplied by CDP? (Select three)
- A.
Device Identifiers
- B.
Capabilities list
- C.
Platform
- D.
Route identifier
- E.
Neighbor traffic data
Correct Answer(s)
A. Device Identifiers
B. Capabilities list
C. PlatformExplanation
CDP (Cisco Discovery Protocol) is a Cisco proprietary protocol that runs between Cisco devices. It is used to discover and gather information about directly connected Cisco devices. The information supplied by CDP includes device identifiers, which are unique identifiers assigned to each Cisco device, capabilities list, which describes the features and functions supported by the device, and platform, which refers to the hardware or software platform on which the device is running. CDP does not supply route identifiers or neighbor traffic data.Rate this question:
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- 12.
Two Certkiller offices are connected as shown below:Two buildings on the London campus of a the Certkiller corporation must be connected to use Ethernet with a bandwidth of at least 100 Mbps. Certkiller is concerned about possible problems from voltage potential differences between the two buildings. Which media type should be used for the connection?
- A.
Coaxial cable
- B.
Fiber optic cable
- C.
UTP cable
- D.
STP cable
- E.
None of the above
Correct Answer
B. Fiber optic cableExplanation
Current Ethernet technololgy typically comes via either copper UTP or fiber ccables. In this scenario the distance between the buildings is only 55 meters so either copper or fiber could be used, as the distance limitation for 100M UTP Ethernet is 100 meters. However, fiber would be a better fit as it is not prone to errors that could occur due to the voltage potential differences. Because fiber is a dielectric material, it's not susceptible to electrical interference. FO-product vendors also claim that fiber systems make secure communications easier. Interference immunity and lack of emissions are givens in FO systems and in the fiber medium itself.Rate this question:
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- 13.
Refer to the Certkiller network shown below: You work as a network technician at Certkiller .com. Please study the exhibit carefully. Based on the information shown above, what is needed to allow host Certkiller 1 to ping host Certkiller 2?
- A.
A crossover cable connecting the switches
- B.
A backbone switch connecting the switches with either fiber optic or straight-through cables
- C.
A straight-through cable connecting the switches
- D.
A CSU/DSU connected to the switches with straight-through cables
- E.
A router connected to the switches with straight-through cables
Correct Answer
E. A router connected to the switches with straight-through cablesExplanation
Routers are Layers 3 devices used for inter-network communication. In this scenario there are two different networks, so both switches need to connect to a router using straight-through cables. A straight-through cable is used to connect two different devices like, switch to router, host to switch. Since we need to insert a router for communication between the two switches, straight through cables will be used between the switches and the router.Rate this question:
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- 14.
As a CCNA candidate, you must know the various layers of the OSI model. At which layers of the OSI Model do Wide Area Networks operate in? (Choose two)
- A.
Physical Layer
- B.
Datalink Layer
- C.
Network Layer
- D.
Session Layer
- E.
Transport Layer
Correct Answer(s)
A. Physical Layer
B. Datalink LayerExplanation
A WAN is a data communications network that covers a relatively broad geographic area and that often uses transmission facilities provided by common carriers, such as telephone companies. WAN technologies generally function at the lower two layers of the OSI reference model: the physical layer and the data link layer as shown below.
Note: Occasionally WAN's would also be considered to operate at layer 3, but since this question asked for only 2 chopices layers 1 and 2 are better choices.Rate this question:
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- 15.
While troubleshooting a connectivity problem on the network, you issue the ping command from your PC command prompt, but the output shows "request times out." At which OSI layer is this problem associated with?
- A.
The data link layer
- B.
The application layer
- C.
The access layer
- D.
The session layer
- E.
The network layer
Correct Answer
E. The network layerExplanation
TCP/IP includes ICMP, a protocol designed to help manage and control the operation of a TCP/IP network. The ICMP protocol provides a wide variety of information about a network's health and operational status. Control message is the most descriptive part of a name. ICMP helps control and manage IP's work and therefore is considered part of TCP/IP's network layer. CCNA Self-Study CCNA ICND exam certification Guide (Cisco Press, ISBN 1-58720-083-X) page 277.Rate this question:
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- 16.
You download a file from an FTP site on the Internet. What is the highest layer in the OSI model used in this FTP operation?
- A.
Application
- B.
Presentation
- C.
Session
- D.
Transport
- E.
Internet
Correct Answer
A. ApplicationExplanation
Layer 7 is the application layer, which is the highest layer in the OSI model. This layer describes the use of end user applications, such as opening movie files (avi, mpeg, etc) used Microsoft Office applications, using WWW browsers, using Telnet, and using FTP.Rate this question:
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- 17.
A host computer has been correctly configured with a static IP address, but the default gateway is incorrectly set. Which layer of the OSI model will be first affected by this configuration error?
- A.
Layer 1
- B.
Layer 2
- C.
Layer 3
- D.
Layer 4
- E.
Layer 5
Correct Answer
C. Layer 3Explanation
IP Addressing and IP routing resides on the OSI Network layer, which is layer 3.Rate this question:
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- 18.
Which layer of the OSI reference model is responsible for ensuring reliable end-to-end delivery of data?
- A.
Application
- B.
Presentation
- C.
Session
- D.
Transport
- E.
Network
Correct Answer
D. TransportExplanation
A key function of the transport layer is to provide connection services for the protocols and applications that run at the levels above it. These can be categorized as either connection-oriented services or connectionless services. Some protocol suites, such as TCP/IP, provide both a connection-oriented and a connectionless transport layer protocol, to suit the needs of different applications. The transport layer is also the place in the layer stack where functions are normally included to add features to end-to-end data transport. Where network layer protocols are normally concerned with just "best effort" communications, where delivery is not guaranteed. Transport layer protocols are given intelligence in the form of algorithms that ensure that reliable and efficient communication between devices takes place. This encompasses several related jobs, including lost transmission detection and handling, and managing the rate at which data is sent to ensure that the receiving device is not overwhelmed. Transmission quality, meaning ensuring that transmissions are received as sent, is so important that some networking references define the transport layer on the basis of reliability and flow-control functions. However, not all transport layer protocols provide these services. Just as a protocol suite may have a connection-oriented and a connectionless transport layer protocol, it may also have one that provides reliability and data management services, and one that does not. Again, this is the case with TCP/IP: there is one main transport layer protocol; TCP, that includes reliability and flow control features, and a second, UDP, that doesn't.Rate this question:
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- 19.
At which OSI layer is a logical path created between two host systems named CK1 and CK2 on the Certkiller LAN?
- A.
Physical
- B.
Session
- C.
Data link
- D.
Transport
- E.
Network
Correct Answer
E. NetworkExplanation
A logical path is created between two host systems at the Network layer of the OSI model. This layer is responsible for routing and addressing, ensuring that data packets are correctly delivered from the source to the destination. Therefore, the logical path between host systems CK1 and CK2 on the Certkiller LAN would be established at the Network layer.Rate this question:
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- 20.
Which OSI layer is associated with the following: The acknowledgement of transmissions, sequencing, and flow control across a network?
- A.
Layer 2
- B.
Layer 3
- C.
Layer 4
- D.
Layer 5
- E.
Layer 6
Correct Answer
C. Layer 4Explanation
The Transport layer (Layer 4) defines several functions, including the choice of protocols. The most important Layer 4 functions are error recovery and flow control. The transport layer may provide for retransmission, i.e., error recovery, and may use flow control to prevent unnecessary congestion by attempting to send data at a rate that the network can accommodate, or it might not, depending on the choice of protocols. Multiplexing of incoming data for different flows to applications on the same host is also performed. Reordering of the incoming data stream when packets arrive out of order is included. Examples include: TCP, UDP, and SPX.Rate this question:
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- 21.
Which OSI layer header contains the address of a destination host that is on another network?
- A.
Application
- B.
Presentation
- C.
Session
- D.
Transport
- E.
Network
Correct Answer
E. NetworkExplanation
The correct answer is Network because the Network layer header contains the address of a destination host that is on another network. This layer is responsible for routing and addressing packets, ensuring that they are delivered to the correct destination across different networks. The Network layer header includes the source and destination IP addresses, which are used to determine the path the packet should take to reach its destination.Rate this question:
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- 22.
Which of the following correctly describe steps in the OSI data encapsulation process? (Choose two)
- A.
The presentation layer translates bits into voltages for transmission across the physical link.
- B.
The transport layer divides a data stream into segments and adds reliability and flow control information.
- C.
Packets are created when the network layer adds Layer 3 addresses and control information to a segment.
- D.
The data link layer adds physical source and destination addresses and an FCS to the segment.
- E.
Packets are created when the network layer encapsulates a frame with source and destination host addresses and protocol-related control information.
Correct Answer(s)
B. The transport layer divides a data stream into segments and adds reliability and flow control information.
C. Packets are created when the network layer adds Layer 3 addresses and control information to a segment.Explanation
The Transport Layer: You can think of the transport layer of the OSI model as a boundary between the upper and lower protocols. The transport layer provides a data transport service that shields the upper layers from transport implementation issues such as the reliability of a connection. The transport layer provides mechanisms for: Segmenting upper layer applications The establishment, maintenance, and orderly termination of virtual circuits Information flow control and reliability via TCP. Transport fault detection and recovery The Network Layer: Layer three of the OSI model is the network layer. The network layer creates and sends packets from source network to destination network. It provides consistent end-to-end packet delivery services and control information. It creates and uses layer 3 addresses for use in path determination and to forward packets. Incorrect Answers: A: This correctly describes the physical layer, not the presentation layer. D: Although the data link layer adds physical (MAC) source and destination addresses, it adds it to a frame, not a segment. E: Packets are encapsulated, not frames.Rate this question:
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- 23.
When files are transferred between a host and an FTP server, the data is divided into smaller pieces for transmission. As these pieces arrive at the destination host, they must be reassembled to reconstruct the original file. What provides for the reassembly of these pieces into the correct order?
- A.
The sequence number in the TCP header
- B.
The Start Frame Delimiter in the 802.3 Preamble
- C.
The TTL in the IP header
- D.
The acknowledgement number in the segment header
- E.
The frame check sequence in the Ethernet frame trailer
Correct Answer
A. The sequence number in the TCP headerExplanation
The Transport layer can provide reliable networking via acknowledgments, sequencing, and flow control. Acknowledgments Delivered segments are acknowledged to the sender. If they are not acknowledged, the sender will retransmit. Sequencing Data segments are sequenced into their original order when they arrive at the destination. Flow Control Provides buffer controls that prevent packet flooding to the destination host. Buffers store bursts of data for processing when the transmission is complete. Layer 4 protocols include the following: Transmission Control Protocol (TCP) User Datagram Protocol (UDP) Sequenced Packet Exchange (SPX)A reliable communications protocol created by Novell NetWareRate this question:
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- 24.
What data structure is described in the exhibit shown above?
- A.
IP datagram
- B.
TCP segment
- C.
Ethernet frame
- D.
UDP datagram
- E.
FDDI frame
Correct Answer
B. TCP segmentExplanation
The exhibit shown above is describing a data structure called a TCP segment. TCP (Transmission Control Protocol) is a protocol used for reliable and ordered delivery of data over a network. A TCP segment is a unit of data that is encapsulated within an IP datagram and transmitted over an Ethernet frame or other network protocols. It contains information such as source and destination port numbers, sequence and acknowledgment numbers, and control flags. Therefore, the correct answer is TCP segment.Rate this question:
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- 25.
Part of the Certkiller network is displayed below:Study the exhibit shown above. Host Certkiller A has established a connection with the Certkiller II server attached to interface E0 of the Certkiller 2 router. Which of the following statements describe the information contained in protocol data units sent from Host Certkiller to Certkiller II? (Choose three)
- A.
The destination port number in a segment header will have a value of 80
- B.
The destination IP address of a packet will be the IP address of the E0 interface of the Certkiller 1 router
- C.
The destination IP address of a packet will be the IP address of the network interface of the Certkiller II server
- D.
The destination address of a frame will be the MAC address of the E0 interface of Certkiller 1 router
Correct Answer(s)
A. The destination port number in a segment header will have a value of 80
C. The destination IP address of a packet will be the IP address of the network interface of the Certkiller II server
D. The destination address of a frame will be the MAC address of the E0 interface of Certkiller 1 routerExplanation
The first statement is correct because the destination port number in a segment header for HTTP traffic is typically 80. The second statement is incorrect because the destination IP address of a packet sent from Host Certkiller to Certkiller II will be the IP address of the network interface of the Certkiller II server, not the E0 interface of Certkiller 1 router. The third statement is correct because the destination IP address of a packet sent from Host Certkiller to Certkiller II will be the IP address of the network interface of the Certkiller II server. The fourth statement is incorrect because the destination address of a frame sent from Host Certkiller to Certkiller II will be the MAC address of the E0 interface of Certkiller 2 router, not Certkiller 1 router.Rate this question:
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- 26.
You have just installed a new web server on the Certkiller network. You are required to ensure that the web server is accessible from the Internet. The network uses private addressing, so an IP-to-registered address mapping is required. To do this, you enter the following command: Certkiller (config)# ip nat inside source static 192.168.2.1 198.18.1.254 You unsuccessfully try to ping the Internet from a PC host on the LAN. During the troubleshooting process, you enter the "show ip nat translations" command but the output is blank. What is the most likely cause of the problem?
- A.
The keyword overload is missing from the command.
- B.
The NAT pool must be defined first.
- C.
An access list must be defined to create static NAT translations.
- D.
The interfaces must be configured for NAT.
- E.
None of the above
Correct Answer
D. The interfaces must be configured for NAT.Explanation
In order to successfully configure a static NAT translation, the interfaces must be configured for NAT, in addition to the global NAT command that was entered. The router interface that lies on the inside part of the network must be defined using the "ip nat inside" command. Similarly, the WAN interface that is being used for the Internet connection must be defined using the "ip nat outside" command. Incorrect Answers: A. In order to make an internal server reachable from the Internet, a static one to one NAT entry must be configured for the server. The keyword "overload" is used to configure many to one NAT, or PAT. B, C. This need not be done in order to create a static NAT entry. These steps are typically done in setting up NAT so that inside LAN users can access the Internet via NAT.Rate this question:
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- 27.
Which protocol below uses TCP port 443 at layer 4?
- A.
HTML
- B.
HTTPS
- C.
TFTP
- D.
Telnet
- E.
SMTP
Correct Answer
B. HTTPSExplanation
HTTPS is the secured version of the HTTP application, which normally uses 128 bit SSL encryption to secure the information sent and received on a web page. An example is a banking web site, or a trustworthy shopping web site that takes credit card information. It is an application layer protocol which uses TCP port 443. Incorrect Answers: A. HTML is not a protocol. C. TFTP uses UDP port 69. D. Telnet uses TCP port 23. E. SMTP uses TCP port 25.Rate this question:
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- 28.
As a CCNA candidate, you will be expected to know the OSI model very well. Which of the following are associated with the application layer (layer 7) of the OSI model? (Choose two)
- A.
TCP
- B.
Telnet
- C.
FTP
- D.
Ping
- E.
IP
Correct Answer(s)
B. Telnet
C. FTPExplanation
The application layer is the top layer of the OSI model and is used to describe the end user applications that can be used over a network. Layer Name Examples Application (layer 7) Telnet, HTTP, FTP, WWW browsers, NFS, SMTP gateways, SNMP
Incorrect Answers: A. TCP resides at layer 4. D. ARP is a function of the data link layer, which is layer 2. E. IP is used at layer 3 (network layer). Reference: CCNA Self-Study CCNA INTRO exam certification Guide (Cisco Press, ISBN 1-58720-094-5) Page 34.Rate this question:
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- 29.
As the Certkiller network administrator, you are required to have a firm understanding of the OSI model. Why does the data communication industry use the layered OSI reference model? (Choose two)
- A.
It enables equipment from different vendors to use the same electronic components, thus saving research and development funds
- B.
It encourages industry standardization by defining what functions occur at each layer of the model
- C.
It divides the network communication process into smaller and simpler components; thus aiding component development, design and troubleshooting
- D.
It provides a means by which changes in functionality in one layer require changes in other layers
- E.
It supports the evolution of multiple competing standards and thus provides business opportunities for equipment manufacturers
Correct Answer(s)
B. It encourages industry standardization by defining what functions occur at each layer of the model
C. It divides the network communication process into smaller and simpler components; thus aiding component development, design and troubleshootingExplanation
The OSI (Open System Interconnection) reference model was created as a reference point for communications devices. A layered approach is used to segment the entire telecommunications process into a series of smaller steps. A is correct because it encourages a level of standardization by encouraging that functions be compared to known layers. D is also correct because it allows engineers to focus on the development, refining, and perfection of simpler components.Rate this question:
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- 30.
You need to describe the various types of flow control to your co-workers. Which of the following are types of flow control that can be used in a network? (Choose three)
- A.
Congestion avoidance
- B.
Windowing
- C.
Cut-through
- D.
Buffering
- E.
Load Balacing
Correct Answer(s)
A. Congestion avoidance
B. Windowing
D. BufferingExplanation
Congestion avoidance, windowing, and buffering are all types of flow control that can be used in a network.
Congestion avoidance is a technique used to prevent network congestion by regulating the flow of data. It involves monitoring the network traffic and taking proactive measures to avoid congestion, such as slowing down the transmission rate or rerouting the data.
Windowing is a flow control mechanism that allows the sender and receiver to negotiate the amount of data that can be sent before an acknowledgment is required. It helps in optimizing the transmission and reception of data by adjusting the window size based on network conditions.
Buffering involves temporarily storing data in a buffer before transmitting or processing it. It helps in managing the flow of data between devices with different processing speeds, ensuring that data is not lost or overwhelmed.
Load balancing, although mentioned in the options, is not a type of flow control. It is a technique used to distribute network traffic evenly across multiple resources to optimize performance and avoid overloading any single resource.Rate this question:
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- 31.
Which of the protocols below use TCP at the transport layer? (Select four)
- A.
TFTP
- B.
SMTP
- C.
FTP
- D.
HTTP
- E.
HTTPS
Correct Answer(s)
B. SMTP
C. FTP
D. HTTP
E. HTTPSExplanation
SMTP (Simple Mail Transfer Profile for email), FTP (File Transfer Protocol), and HTTP/HTTPS (Hyper Text Transfer Protocol for internet) all use TCP because of the reliable delivery mechanism. SMTP uses TCP port 25, FTP uses TCP ports 20 and 21, HTTP uses TCP port 80, and HTTPS uses TCP port 443. Incorrect Answers: A, C: SNMP and TFTP use UDP as the transport mechanism. Generally speaking, protocols that use the keywords "trivial" or "simple" uses UDP, since connectionless, best effort delivery mechanism usually suffice. Reference: CCNA Self-Study CCNA INTRO exam certification Guide (Cisco Press, ISBN 1-58720-094-5) Page 163.Rate this question:
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- 32.
- A.
This is a UDP header
- B.
This is an OSI layer 4 header.
- C.
This is traffic from an FTP server.
- D.
This is traffic from an Telnet client.
- E.
The last PDU received in this session had a sequence number of 292735.
Correct Answer(s)
B. This is an OSI layer 4 header.
C. This is traffic from an FTP server.
E. The last PDU received in this session had a sequence number of 292735.Explanation
As the header contains the sequence number and ACK number fields, it represents a TCP header. Choice B is correct as TCP works on Layer 4 i.e. Transport Layer. Source Port mentioned in the header is 21 which indicate it is FTP Traffic because FTP uses port 20 and 21 for data and control. So choice C is correct. The acknowledgment number refers to the sequence number of the last PDU received, which is 292735, making choice E also correct.Rate this question:
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- 33.
Which fields are included in the TCP header? (Choose three).
- A.
Source Port
- B.
Acknowledgement Number
- C.
Request Number
- D.
Destination Address
- E.
Window
Correct Answer(s)
A. Source Port
B. Acknowledgement Number
E. WindowExplanation
Source Port: 16 bits. Destination Port: 16 bits. Sequence Number: 32 bits. The sequence number of the first data byte in this segment. If the SYN bit is set, the sequence number is the initial sequence number and the first data byte is initial sequence number + 1.
Acknowledgment Number: 32 bits. If the ACK bit is set, this field contains the value of the next sequence number the sender of the segment is expecting to receive. Once a connection is established this is always sent. Data Offset: 4 bits. The number of 32-bit words in the TCP header. This indicates where the data begins. The length of the TCP header is always a multiple of 32 bits. Reserved: 3 bits. Must be cleared to zero. ECN, Explicit Congestion Notification: 3 bits. Added in RFC 3168. Control Bits: 6 bits. Window: 16 bits, unsigned. The number of data bytes beginning with the one indicated in the acknowledgment field which the sender of this segment is willing to accept. Checksum: 16 bits. This is computed as the 16-bit one's complement of the one's complement sum of a pseudo header of information from the IP header, the TCP header, and the data, padded as needed with zero bytes at the end to make a multiple of two bytes. Urgent Pointer: 16 bits, unsigned. If the URG bit is set, this field points to the sequence number of the last byte in a sequence of urgent data. Options: 0 to 44 bytes. Options occupy space at the end of the TCP header. All options are included in the checksum. An option may begin on any byte boundary. The TCP header must be padded with zeros to make the header length a multiple of 32 bits. Data: Variable length.Rate this question:
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- 34.
Acknowledgements, sequencing, and flow control are functions that are handled by which layer of the OSI model?
- A.
Layer 5
- B.
Layer 4
- C.
Layer 7
- D.
Layer 6
- E.
Layer 3
Correct Answer
B. Layer 4Explanation
Layer 4 of the OSI model is responsible for the functions of acknowledgements, sequencing, and flow control. This layer is known as the Transport Layer. It ensures that data is delivered reliably and in the correct order by providing error detection and correction, as well as managing the flow of data between the source and destination.Rate this question:
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- 35.
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.
Start a new session using UDP
- B.
Obtain a new IP address from the DHCP server
- C.
Use a different source port for the session
- D.
Decrease the sequence number
- E.
Decrease the window size
Correct Answer
E. Decrease the window sizeExplanation
A TCP window the amount of outstanding (unacknowledged by the recipient) data a sender can send on a particular connection before it gets an acknowledgment back from the receiver that it has gotten some of it. For example if a pair of hosts are talking over a TCP connection that has a TCP window size of 64 KB (kilobytes), the sender can only send 64 KB of data and then it must stop and wait for an acknowledgment from the receiver that some or all of the data has been received. If the receiver acknowledges that all the data has been received then the sender is free to send another 64 KB. One way to improve the reliability of the TCP connection is to reduce the window size that the receiver needs to receive before sending an acknowledgement. However, this will reduce throughput as more segments and acknowledgements will need to be sent in order to transfer the same amount of data.Rate this question:
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- 36.
You have set up an Internet based FTP server, where people can upload and download files. In terms of the OSI model, what is the highest layer used during the FTP sessions.
- A.
Application
- B.
Presentation
- C.
Session
- D.
Transport
- E.
Internet
Correct Answer
A. ApplicationExplanation
The application layer is the highest layer (layer 7) of the OSI model, and is reserved for end user applications. Since FTP is itself an application, layer 7 is the highest layer used. Incorrect Answers: B, C, D, E, F, G. In any given FTP session, all of these layers will be used at some point but they are incorrect because the question asked for the highest layer used by FTP.Rate this question:
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- 37.
ICMP is often used in troubleshooting and verifying network. What statements are true regarding ICMP packets? (Choose two)
- A.
They acknowledge receipt of TCP segments.
- B.
They guarantee datagram delivery.
- C.
They can provide hosts with information about network problems.
- D.
They are encapsulated within IP datagrams.
- E.
They are encapsulated within UDP datagrams.
Correct Answer(s)
C. They can provide hosts with information about network problems.
D. They are encapsulated within IP datagrams.Explanation
ping may be used to find out whether the local machines are connected to the network or whether a remote site is reachable. This tool is a common network tool for determining the network connectivity which uses ICMP protocol instead of TCP/IP and UDP/IP. This protocol is usually associated with the network management tools which provide network information to network administrators, such as ping and traceroute (the later also uses the UDP/IP protocol). ICMP is quite different from the TCP/IP and UDP/IP protocols. No source and destination ports are included in its packets. Therefore, usual packet-filtering rules for TCP/IP and UDP/IP are not applicable. Fortunately, a special "signature" known as the packet's Message type is included for denoting the purposes of the ICMP packet. Most commonly used message types are namely, 0, 3, 4, 5, 8, 11, and 12 which represent echo reply, destination unreachable, source quench, redirect, echo request, time exceeded, and parameter problem respectively. In the ping service, after receiving the ICMP "echo request" packet from the source location, the destination Incorrect Answers ICMP is an IP protocol so A and E are incorrect. ICMP doesn't guarantee datagram delivery so B is wrong as well.Rate this question:
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- 38.
Which of the following services use TCP? (Choose three)
- A.
DHCP
- B.
SMTP
- C.
SNMP
- D.
FTP
- E.
HTTP
Correct Answer(s)
B. SMTP
D. FTP
E. HTTPExplanation
TCP (Transmission Control Protocol) is a reliable mechanism for data delivery. SMTP, FTP and HTTP services use TCP via ports 25, 20/21, and 80, respectively.Rate this question:
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- 39.
Which of the following are types of flow control? (Choose three)
- A.
Buffering
- B.
Cut-through
- C.
Windowing
- D.
Congestion avoidance
- E.
Load balancing
Correct Answer(s)
A. Buffering
C. Windowing
E. Load balancingExplanation
Data transmission flow control occurs at layer 4 with the help of buffering, windowing and congestion avoidance. Reference: CCNA Cisco Certified Network Associate Study Guide, 5th Edition, Todd Lammle, chapter 1, page 17.Rate this question:
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- 40.
Which Layer 4 protocol is used for a Telnet connection between two Certkiller routers?
- A.
IP
- B.
ICMP
- C.
DNS
- D.
TCP
- E.
UDP
Correct Answer
D. TCPExplanation
TCP is a reliable connection-oriented protocol. TCP uses acknowledgments, sequencing, and flow control to ensure reliability. Telnet uses TCP port 23.Rate this question:
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- 41.
FTP, Telnet, DNS, and SMTP are all protocols being used in the Certkiller network. Of these, which uses both TCP and UDP ports?
- A.
Telnet
- B.
FTP
- C.
DNS
- D.
SMTP
- E.
None of the above
Correct Answer
C. DNSExplanation
The following port numbers for the protocols listed above are as follows:
FTP: TCP Port 20 and 21 SMTP: TCP Port 25 Telnet: TCP Port 23 DNS: both TCP and UDP Port 53Rate this question:
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- 42.
Certkiller is installing IP phones in a new office. The phones and office computers connect to the same device. To ensure maximum throughout for the phone data sessions, the company needs to make sure that the phone traffic is on a different network from that of the office computer data traffic. What is the best network device to which to directly connect the phones and computers and what technology should be implemented on this device? (Choose two)
- A.
VLAN
- B.
Subinterface
- C.
STP
- D.
Hub
- E.
Switch
Correct Answer(s)
A. VLAN
E. SwitchExplanation
The best network device to directly connect the phones and computers is a switch. A switch allows for the creation of virtual LANs (VLANs) which can separate the phone traffic from the office computer data traffic. By implementing VLANs on the switch, the company can ensure that the phone data sessions have maximum throughput without interfering with the office computer data traffic.Rate this question:
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- 43.
The corporate head office of Certkiller has a teleconferencing system that uses VOIP (voice over IP) technology. This system uses UDP as the transport for the data transmissions. If these UDP datagrams arrive at their destination out of sequence, what will happen?
- A.
UDP will send an ICMP Information Request to the source host.
- B.
UDP will pass the information in the datagrams up to the next OSI layer in the order that they arrive.
- C.
UDP will drop the datagrams.
- D.
UDP will use the sequence numbers in the datagram headers to reassemble the data in the correct order.
- E.
UDP will not acknowledge the datagrams and wait for a retransmission of the datagrams.
Correct Answer
B. UDP will pass the information in the datagrams up to the next OSI layer in the order that they arrive.Explanation
VOIP systems utilize UDP because it is faster and uses less overhead. In addition, the reliable transport mechanism used in TCP is useless to VOIP because if a packet gets dropped and needs to be resent, it will be already too late. UDP provides a service for applications to exchange messages. Unlike TCP, UDP is connectionless and provides no reliability, no windowing, and no reordering of the received data. However, UDP provides some functions of TCP , such as data transfer, segmentation, and multiplexing using port numbers, and it does so with fewer bytes of overhead and with less processing required. UDP data transfer differs from TCP data transfer in that no reordering or recovery is accomplished. Applications that use UDP are tolerant of lost data, or they have some application mechanism to recover data loss. Reference: CCNA Self-Study CCNA INTRO exam certification Guide (Cisco Press, ISBN 1-58720-094-5) Page 161.Rate this question:
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- 44.
Part of the Certkiller network is shown below:You work as a network technician for Certkiller and are responsible for this network. Based on the diagram shown above, how many collision domains are there?
- A.
Six
- B.
Fourteen
- C.
Four
- D.
Two
- E.
Three
Correct Answer
D. TwoExplanation
The multi-segment configuration guidelines apply only to a single Ethernet "collision domain." A collision domain is formally defined as a single CSMA/CD network in which there will be a collision if two computers attached to the system transmit at the same time. An Ethernet system composed of a single segment or multiple segments linked with repeaters is a network that functions as a single collision domain.Rate this question:
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- 45.
You work as a network technician at Certkiller .com. You have been assigned the task of designing a new Certkiller internetwork. The main priority is to achieve the highest reliability available. Certkiller .com is willing to spend more dollars to avoid downtime caused by link failure. Which of the following four designs is to be preferred?
- A.
Design Certkiller A
- B.
Design Certkiller B
- C.
Design Certkiller C
- D.
Design Certkiller D
Correct Answer
A. Design Certkiller AExplanation
A network topology that is set up so that each device is directly connected to every other device on the network. This connection method has built-in redundancy. If one link goes down, the device will transmit via another link. Example: If the partial mesh design is a compromise between the network administrators and managers, then the full mesh design implies that the network administrators won. This design is every Cisco network administrator's picture of perfection over a Frame Relay cloud. It gives every site a direct virtual circuit to every other site, as shown in Figure This design gives maximum redundancy and minimum packet latency (latency describes how long it takes a packet to reach each location).Rate this question:
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- 46.
You work as a network technician at Certkiller .com. You have been assigned the task of designing a new Certkiller internetwork. The main priority is the achieve the highest reliability available, however not at all costs. Certkiller .com is willing to spend more dollars to avoid downtime caused by link failure. Which of the following four designs would provide some redundancy and increase reliability for all four sites, but would cost less than a fully redundant topology?
- A.
Design Certkiller A
- B.
Design Certkiller B
- C.
Design Certkiller C
- D.
Design Certkiller D
Correct Answer
B. Design Certkiller BExplanation
You can think of the partial mesh Frame Relay design as the compromise between network administrators and cost-saving managers.Rate this question:
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- 47.
You work as a network technician at Certkiller .com. You have been assigned the task of designing a new Certkiller internetwork. The main priority is to minimize the link costs. Certkiller .at the same time wants to ensure the branch offices with direct connectity to the main site. Which of the following four designs is to be preferred?
- A.
Design Certkiller A
- B.
Design Certkiller B
- C.
Design Certkiller C
- D.
Design Certkiller D
Correct Answer
C. Design Certkiller CExplanation
Every network looks for cost efficiency. Redundancy is often sacrificed on the altar of monthly cost. Thus, the hub and spoke Frame Relay network design is one of the more common. In this configuration, you pick a centralized location (most likely, your largest, most connected office) as the "hub" of the network. All other locations are considered "spokes" and have a single virtual circuit connection back to the hub. The major advantage of this configuration is the cost. It offers the cheapest monthly price tag, which cost-cutting corporations enjoy. The disadvantages are beginning to mount against this design, however. The redundancy is sorely lacking. If a single router (the central router) loses connectivity for any reason (if the router crashes, if a trenching company cuts through the line), your entire WAN goes down. The other disadvantage of this design is beginning to eclipse even redundancy. It is the disadvantage of tandem switching. Any time the spoke offices need to reach each other, they must go through the hub office.Rate this question:
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- 48.
A Certkiller network is shown in the exhibit below:The routers in this network are running RIPv2. Which addressing scheme would satisfy the needs of this network yet waste the fewest addresses?
- A.
Network 1: 192.168.10.0/26Network 2: 192.168.10.64/26Network 3: 192.168.10.128/26Serial link 1: 192.168.20.0/24Serial link 2: 192.168.30.0/24
- B.
Network 1: 192.168.10.0/26Network 2: 192.168.10.64/28Network 3: 192.168.10.80/29Serial link 1: 192.168.10.88/30Serial link 2: 192.168.10.96/30
- C.
Network 1: 192.168.10.0/26Network 2: 192.168.10.64/27Network 3: 192.168.10.96/28Serial link 1: 192.168.10.112/30Serial link 2: 192.168.10.116/30
- D.
Network 1: 192.168.10.0/27Network 2: 192.168.10.64/28Network 3: 192.168.10.96/29Serial link 1: 192.168.10.112/30Serial link 2: 192.168.10.116/30
Correct Answer
C. Network 1: 192.168.10.0/26Network 2: 192.168.10.64/27Network 3: 192.168.10.96/28Serial link 1: 192.168.10.112/30Serial link 2: 192.168.10.116/30Explanation
Required Number of hosts :50 When We use the 26 bits for Network : 11111111.11111111.11111111.11000000 so 62 usable host can be in one network. 50 host for now and remaining hosts address for further growth. Network 2 Required Number of Hosts: 20
When we use the 27 bits for Network: 11111111.11111111.1111111.11100000 so 30 usable hosts can be in one network. Network 3 Required Number of Hosts: 10
When we use the 28 bits for Network: 11111111.11111111.11111111.11110000 so 14 usable hosts can be in one network. Connection between CK1 , CK2 and CK3 is WAN so when you use 30 bits network IP, you will not lose any IP addresses from network since this subnet allows for only 2 host addresses.Rate this question:
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- 49.
The Certkiller network is shown below:A technician is investigating a problem with the network shown above. These symptoms have been observed: 1. All of the user hosts can access the Internet. 2. None of the user hosts can access the server in VLAN9 3. All of the hosts can ping each other. What could cause the symptoms?
- A.
Interface S0/0 on the router is down.
- B.
Interface Fa0/1 on the router is down.
- C.
Interface Fa0/5 on Certkiller 3 is down.
- D.
Interface Fa0/4 on Certkiller 3 is down.
- E.
Certkiller 2 is turned off.
Correct Answer
D. Interface Fa0/4 on Certkiller 3 is down.Explanation
Since all user hosts have access to internet, link to router has to be up. Therefore, router interface (Fa0/1 - believe it is labeled incorrectly on diagram as Fa1/0) must be up. Since all hosts can ping each other, but none can get to VLAN 9 which is through single interface Fa0/4, this interface must be down. Choice A: incorrect, S0/0 must be up if internet access available. Choice B: incorrect, Fa0/1 must be up if internet access (through router) available. Choice C: incorrect, would not prevent access to VLAN9 via other routes (i.e Fa0/7, Fa0/9, Fa0/4) Choice D: correct Choice E: incorrect: Certkiller 2 must be up if internet access (through switch and then router) available Choice F: incorrect: Disabled trunking on link between Certkiller 1 and Certkiller 3 would not prevent access to VLAN9 via other routesRate this question:
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- 50.
Refer to the graphic shown below:
- A.
Picture A
- B.
Picture B
- C.
Picture C
- D.
Picture D
Correct Answer
D. Picture DExplanation
From the output shown in this question, we can see that there a numerous different MAC addresses associated with port Fa 0/23. This can only mean that a device with multiple hosts attached to it is plugged into this port, such as a hub or another switch.Rate this question:
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