CPSC 353 final

The stop-and-wait protocol is highly inefficient when

. when there is a large distance between source and destination and the transmission rate is high

A port number is _______ bits long.

16

There are ______ bytes in a typical TCP header, if it does not have options

20

The standard port for connecting to an ssh server is port ___

22

The standard port for connecting to an SMTP server is port ___

25

There are _____ bits in the TCP sequence number field

32

You are sending a 30 Mbit MP3 file from a source host to a destination host. All links in the path between source and destination have a transmission rate of 10 Mbps. Assume that the propagation speed is 2 * 10^8 meters/sec, and the distance between source and destination is 10,000 km. Suppose there is only one link between source and destination. Also suppose that the entire MP3 file is sent as one packet. How many bits will the source have transmitted when the first bit arrives at the destination?

500,000

Each line in an HTTP request message, before the entity body, is terminated with

An ASCII 13 character followed by an ASCII 10 character

. With GBN, it is possible for the sender to receive and ACK for a packet that falls outside of its current window.

At t 3 the receiver receives the duplicates and re-acknowledges 1, 2, 3. At t 4 the sender receives the ACKs that the receiver sent at t1 and advances its window to 4, 5, 6. At t 5 the sender receives the ACKs 1, 2, 3 the receiver sent at t 2 . These ACKs are outside its window. b) True. By essentially the same scenario as in (a).

Over a TCP connection without the SACK option, suppose host A sends two segments to host B, host B sends an acknowledgment for each segment, the first acknowledgment is lost, but the second acknowledgment arrives before the timer for the first segment expires.

Host A will retransmit neither segments

A socket address is a combination of __________.

None of the choices are correct

The technique of allowing a sender to send multiple packets without waiting for acknowledgements is known as ____________

Pipelining

How does SMTP mark the end of a message body?

SMTP uses a line containing only a period to mark the end of a message body

What is the difference between MAIL FROM: in SMTP and From: in the mail message

The MAIL FROM: in SMTP is a message from the SMTP client that identifies the sender of the mail message to the SMTP server. The From: on the mail message itself is NOT an SMTP message, but rather is just a line in the body of the mail message.

With the SR protocol, it is possible for the sender to receive an ACK for a packet that falls outside of its current window.

True. Suppose the sender has a window size of 3 and sends packets 1, 2, 3 at t 0 . At t1 (t1 > t 0) the receiver ACKS 1, 2, 3. At t 2 (t 2 > t1) the sender times out and resends 1, 2,

The transport-layer packet in the TCP/IP protocol suite is called

a segment or a user datagram

Pipelining requires which of the following

all of the above

A client program normally uses ____________ port number. A server program normally uses __________ port number.

an ephemeral; a well-known

The Internet Protocol (IP) is ________ protocol.

an unreliable

The application layer in the TCP/IP protocol suite is usually considered to be the combination of ________ layers in the OSI model

application, presentation, and session

__________ control refers to the mechanisms and techniques to keep the load below the capacity of the network.

congestion

In TCP's __________ algorithm the size of the congestion window increases additively until congestion is detected.

congestion avoidance

Propagation delay (time) is the ratio of ______________________.

distance to propagation speed

The maximum amount of data that can be placed in a segment is limited by the maximum transmission unit (MTU)

false

When an SMTP connection is established, the first message is passed

from server to client

In __________ resolution, the server returns the IP address of the server that it thinks can resolve the query.

iterative

In TCP, the _______ timer prevents a long idle connection between two TCPs.

keepalive

In TCP, the size of the send window is the ________ of rwnd and cwnd.

minimum

In TCP, the value of the acknowledgment field in a sent segment defines the sequence number related to the ______ byte a party expects to receive next.

next

In TCP, an ACK segment, if carrying no data, consumes ______ sequence number(s).

no

In TCP, a special segment called a probe is sent by a sending TCP when the _______ timer goes off.

persistence

The first section of a URL identifier is the __________.

protocol

In TCP's ________ algorithm the size of the congestion window increases exponentially until it reaches a threshold.

slow start

c. The bandwidth‐delay product is

the maximum number of bits that can be in the link at a given time

The alternating-bit protocol is the same as the GBN protocol with a sender and receive window size of 1

the packet is accepted as a single packet within the window and ACK is treated as an ordinary acknowledgement

In modern implementations of TCP, a retransmission occurs if the retransmission timer expires or ________ duplicate ACK segments have arrived.

three

The alternating-bit protocol is the same as the SR protocol with a sender and receive window size of 1

true, the sequence number packet alternate between 0 and 1, so the sender and receiver windows will not occur at the same time therefore sender and receiver SR protocol is 1