Computer
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Computer Networks MCQ - SET 08
1. What are the
types of acknowledgements (ACKs) used in typical TCP implementation?
(a) Selective ACKs
only
(b) Both selective
and cumulative ACKs
(c) Both positive
and negative ACKs
(d) Positive, cumulative,
selective and lookahead ACKs
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Ans : (d)
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Answer: (d)
Positive, cumulative, selective and lookahead ACKs
TCP is a connection-oriented
protocol. It guarantees delivery of data and also guarantees that packets
will be delivered in the same order in which they were sent. It uses
acknowledgements to ensure the integrity of the data flow.
Positive
ACK:
acknowledgement to the sender on correctly received packets.
Cumulative
ACK:
acknowledgement on reception of data packets with the sequence number of
highest in-order data received.
Selective
ACK:
acknowledgement that indicates the sequence number of every data packet
received.
Lookahead
ACK:
the use of sequence number used as acknowledgement number.
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2. What would be
the approximate transmission time a 10 Mbps (Megabits per second) Ethernet LAN
take to send a 1200 byte data packet?
(a) 1 ms
(b) 2 ms
(c) 5 ms
(d) 10 ms
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Ans : (a)
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Answer: (a)
1 ms
Packet transmission time can be
calculated as follows;
Transmission time = Packet size (in
bits) / Transmission rate (in bits/s)
For this question;
Transmission time = (1200 * 8 bit) /
(10 * 106 bits/sec) = 0.00096 sec ≈ 1 ms.
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3. Internet Message
Access Protocol (IMAP) runs between email
(a) sender’s mail
client and sender’s outgoing mail server
(b) receiver’s mail
client and receiver’s incoming mail server
(c) sender’s mail
server and receiver’s mail server
(d) sender’s mail
client and receiver’s mail client
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Ans : (b)
|
Answer: (b)
receiver’s mail client and receiver’s incoming mail server
IMAP was designed with the goal of
permitting complete management of an email box by multiple email clients,
therefore clients generally leave messages on the server until the user
explicitly deletes them. Whenever you check your inbox, your email client
contacts the server to connect you with your messages. When you read an email
message using IMAP, you aren’t actually downloading or storing it on your computer;
instead, you are reading it off of the server. As a result, it’s possible to
check your email from several different devices without missing a thing.
[Refer here for more]
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4. Let us suppose
that all of the network sources occasionally have data to send over the
network. Which of the following would be most suitable for such a scenario?
(a) Circuit
switching
(b) Packet
switching
(c) Both circuit
and packet switching
(d) Neither of them
is true
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Ans : (b)
|
Answer: (b)
Packet switching
Packet-switching is better here
because there are statistical multiplexing gains – when a source does not
have data to send, it will not be allocated bandwidth (that would be idle).
Hence this bandwidth is available for use by other sources.
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5. Which among the
following protocols has out-of-band control messages?
(a) HTTP
(b) TCP
(c) SMTP
(d) FTP
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Ans : (d)
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Answer: (d)
File Transfer Protocol (FTP)
Out-of-band control is a
characteristic of network protocols with which data control is regulated.
Out-of-band control passes control data on a separate connection from main
data. Protocols such as FTP use out-of-band control. FTP handles control
information in one connection and the data files in the other.
HTTP, TCP and SMTP have in-band
control messages. It means that
control message and data messages may be interleaved with each other on the
same connection.
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Related links
Why do we use ACK in TCP?
Why packet switching is better than circuit switching for the network resources that send occasionally?
Define Internet Message Access Protocol (IMAP)
How to calculate the transmission time required to send a data packet over network?
Multiple choice questions in computer networks
