26/02/2014

Data Communication - Networking PK Bits PDF


Data Communication and Networking Bits

Why should you delete unknown e-mail attachments ?
(A) You could go to jail
(B) The person could track you down and hurt you
(C) It is bad manners
(D) It might contain a virus that could hurt your computer
Ans: D

Participants can see and hear each other in a/an ………………
(A) electronic mail system    (B) message system
(C) tele-conference               (D) bulletin board
Ans: C

What are the two parts of an E-mail address ?
(A) User name and street address
(B) Legal name and phone number
(C) User name and domain name
(D) Initials and password
Ans: C

The word FTP stands for__________
(a) File Translate Protocol   (b) File Transit Protocol
(c) File Typing Protocol      (d) File Transfer Protocol
Ans:- D

A method to provide secure transmission of email is called ____.
A. TLS     B. SA     C. IPSec      D. PGP
Ans:- C

We access the World Wide Web using–
(A) Browsers            (B) Instant messaging applications
(C) High bandwidth (D) Search engine
Ans:- a

What are the components of a packet switch?
A. input ports, output ports, a router processor, a switching fabric
B. input ports, output ports, a router processor.
C. input ports, output ports, a switching fabric
D. input ports, output ports, a router processing, a switching fabric, a memory chip
Ans:- b
Explanation: A packet switch has four components: input ports, output ports, the routing processor, and the switching fabric.

What are the three phases in virtual circuit switching?
A. Setup, data transfer, teardown
B. request-connect, data sending-acknowledgment, request-disconnect
C. send-connect, data transfer, request-disconnect
D. none of above

How switching is performed in the internet?
A. data gram approach to circuit switching at datalink layer
B. Virtual circuit approach to message switching at network layer
C. datagram approach to message switching at datalink layer
D. datagram approach to packet switching at network layer

Which of the following field of the TCP header tells how many bytes may be sent starting at the byte acknowledged?
A. TCP header length B. Window size
C. Acknowledgement number D. Urgent pointer

The output of a Ethernet card is connected to the data encoder/decoder, which in turn is connected to the transmission cable through a
a. Repeater b. Transceiver c. Segments d. Groups
Ans:- a

In Ethernet when Manchester encoding is used, the bit rate is:
(a) Half the baud rate (b) Twice the baud rate
(c) Same as the baud rate (d) None of the above
Ans: Option (a)
Explanation: Manchester coding is the process by which digital information in a binary bit stream is converted into electrical signals for transmission. It uses a two state transition of line voltage to represent one bit of information. In other words, two baud (voltage changes) is used for one bit (piece of information). Manchester coding has the advantage of enabling data to be transmitted without the need for an extra clocking signal.

The transport layer protocols used for real time multimedia, file transfer, DNS and email respectively are
(a) TCP, UDP, UDP and TCP
(b) UDP, TCP, TCP and UDP
(c) UDP, TCP, UDP and TCP
(d) TCP, UDP, TCP and UDP
Ans: option(c)
Explanation: Real Time Multimedia: Data packets should be delivered faster. Also it can be unreliable. Therefore UDP.

File Transfer: For example downloading a file. It should be secure and reliable. Therefore TCP.

DNS: uses both UDP and TCP for its transport. But to achieve efficiency DNS uses UDP. To start a TCP connection a minimum of three packets are required (SYN out, SYN+ACK back, ACK out). UDP uses a simple transmission model with a minimum of protocol mechanism. UDP has no handshaking dialogues.

Email: uses SMTP protocol which uses TCP protocol. Standard applications using UDP include:
Trivial File Transfer Protocol (TFTP)
Domain Name System (DNS) name server
Remote Procedure Call (RPC), used by the Network File System (NFS)
Simple Network Management Protocol (SNM P)
Lightweight Directory Access Protocol (LDAP)
TCP is utilized extensively by
World Wide Web (WWW)
E-mail
File Transfer Protocol
Secure Shell
Peer-to-Peer file sharing

One of the header fields in an IP datagram is the Time to Live (TTL) field. Which of the following statements best explains the need for this field?
(a) It can be used to priortize packets
(b) It can be used to reduce delays
(c) It can be used to optimize throughput
(d) It can be used to prevent packet looping
Ans: (d)

In the slow start phase of the TCP congestion control algorithm, the size of the congestion window
(a) does not increase           (b) increases linearly
(c) increases quadratically (d) increases exponentially
Ans: option (d)

Which of the following system calls results in the sending of SYN packets?
(a) socket (b) bind (c) listen (d) connect
Ans: option (d)

The protocol data unit(PDU) for the application layer in the Internet stack is
(a) Segment (b) Datagram (c) Message (d) Frame
Ans: (c)
Explanation:
PDU for Application Layer - Message
PDU for Internet Layer - Datagram
PDU for Transport Layer - Segment
PDU for Link Layer – Frame

Which of the following transport layer protocols is used to support electronic mail?
(a) SM TP (b) IP (c) TCP (d) UDP
Ans: (c)
Explanation: Application Layer protocol for sending email is SM TP (Simple Mail Transfer Protocol). SM TP is a connection oriented protocol; therefore it uses TCP at Transport Layer.
Note:
IP - It is a network layer protocol.
UDP - is a connection-less transport layer protocol.

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