22 04 2014

2014 Cisco 100-101 Exam Dump(51-60)

QUESTION 51
Which OSI layer header contains the address of a destination host that is on another network?

A.    application
B.    session
C.    transport
D.    network
E.    data link
F.    physical

Answer: D
Explanation:
Only network address contains this information. To transmit the packets the sender uses network address and datalink address. But the layer 2 address represents just the address of the next hop device on the way to the sender. It is changed on each hop. Network address remains the same.

QUESTION 52
Which layer of the TCP/IP stack combines the OSI model physical and data link layers?

A.    Internet layer
B.    transport layer
C.    application layer
D.    network access layer

Answer: D
Explanation:
The Internet Protocol Suite, TCP/IP, is a suite of protocols used for communication over the internet. The TCP/IP model was created after the OSI 7 layer model for two major reasons. First, the foundation of the Internet was built using the TCP/IP suite and through the spread of the World Wide Web and Internet, TCP/IP has been preferred. Second, a project researched by the Department of Defense (DOD) consisted of creating the TCP/IP protocols. The DOD’s goal was to bring international standards which could not be met by the OSI model. Since the DOD was the largest software consumer and they preferred the TCP/IP suite, most vendors used this model rather then the OSI. Below is a side by side comparison of the TCP/IP and OSI models.
TCP/IP Model
VS.
OSI Model Application Layer 7
Application
Layer 6
Presentation
Layer 5
Session Transport Layer 4
Transport Internet Layer 3
Network Network Access Layer 2
Data Link
Layer 1
Physical

QUESTION 53
Which protocol uses a connection-oriented service to deliver files between end systems?

A.    TFTP
B.    DNS
C.    FTP
D.    SNMP
E.    RIP

Answer: C

different network, the host will know to send the frame to its default gateway, which is Toronto.

QUESTION 54
Which network device functions only at Layer 1 of the OSI model?

A.
B.
C.
D.
E.

Answer: C
Explanation:
Most hubs are amplifying the electrical signal; therefore, they are really repeaters with several ports. Hubs and repeaters are Layer 1 (physical layer) devices.

QUESTION 55
Which transport layer protocol provides best-effort delivery service with no acknowledgment receipt required?

A.    HTTP
B.    IP
C.    TCP
D.    Telnet
E.    UDP

Answer: E
Explanation:
UDP provides a connectionless datagram service that offers best-effort delivery, which means that UDP does not guarantee delivery or verify sequencing for any datagrams. A source host that needs reliable communication must use either TCP or a program that provides its own sequencing and acknowledgment services.

QUESTION 56
Which layer of the OSI model controls the reliability of communications between network devices using flow control, sequencing and acknowledgments?

A.    Physical
B.    Data-link
C.    Transport
D.    Network

Answer: C
Explanation:
There are many services that can be optionally provided by a transport-layer protocol, and different protocols may or may not implement them. Connection-oriented communication: It is normally easier for an application to interpret a connection as a data stream rather than having to deal with the underlying connection-less models, such as the datagram model of the User Datagram Protocol (UDP) and of the Internet Protocol (IP). Byte orientation:
Rather than processing the messages in the underlying communication system format, it is often easier for an application to process the data stream as a sequence of bytes. This simplification helps applications work with various underlying message formats. Same order delivery: The network layer doesn’t generally guarantee that packets of data will arrive in the same order that they were sent, but often this is a desirable feature. This is usually done through the use of segment numbering, with the receiver passing them to the application in order. This can cause head-of-line blocking. Reliability: Packets may be lost during transport due to network congestion and errors. By means of an error detection code, such as a checksum, the transport protocol may check that the data is not corrupted, and verify correct receipt by sending an ACK or NACK message to the sender. Automatic repeat request schemes may be used to retransmit lost or corrupted data.
Flow control: The rate of data transmission between two nodes must sometimes be managed to prevent a fast sender from transmitting more data than can be supported by the receiving data buffer, causing a buffer overrun. This can also be used to improve efficiency by reducing buffer underrun. Congestion avoidance: Congestion control can control traffic entry into a telecommunications network, so as to avoid congestive collapse by attempting to avoid oversubscription of any of the processing or link capabilities of the intermediate nodes and networks and taking resource reducing steps, such as reducing the rate of sending packets. For example, automatic repeat requests may keep the network in a congested state; this situation can be avoided by adding congestion avoidance to the flow control, including slow-start. This keeps the bandwidth consumption at a low level in the beginning of the transmission, or after packet retransmission. Multiplexing: Ports can provide multiple endpoints on a single node. For example, the name on a postal address is a kind of multiplexing, and distinguishes between different recipients of the same location. Computer applications will each listen for information on their own ports, which enables the use of more than one network service at the same time. It is part of the transport layer in the TCP/IP model, but of the session layer in the OSI model.

QUESTION 57
Drag and Drop Question

Answer: