CNT Midterm Review (Quiz Questions/Answers)

Compared with packet switching, what is an advantage of circuit switching?

Better security

Higher bandwidth utilization

No transmission errors

Better performance guarantees

Better performance guarantees

Compared with circuit switching, what is an advantage of packet switching?

Better performance guarantees

Better security

Higher bandwidth utilization

No transmission errors

Higher bandwidth utilization

Consider two hosts, A and B, connected by a single link of rate 1 Mbps. Suppose that the two hosts are separated by 3,000 Km, and suppose the propagation speed along the link is 3 × 10^8 m/s. Host A is to send a packet of 1,000 bytes to Host B. Calculate the transmission delay in seconds.

0.08

0.001

0.008

0.01

0.008

Consider two hosts, A and B, connected by a single link of rate 1 Mbps. Suppose that the two hosts are separated by 3,000 Km, and suppose the propagation speed along the link is 3 × 10^8 m/s. Host A is to send a packet of 1,000 bytes to Host B. Calculate the propagation delay in seconds.

0.01

0.001

0.008

0.08

0.01

Layer 2 refers to the second layer (from the bottom, i.e., the physical layer as the first layer) in the Internet protocol stack, which is the

Application layer

Network layer

Link layer

Transport layer

Link Layer

Which of the following protocols is based on the peer-to-peer architecture?

DNS

HTTP

SMTP

Bittorrent

Bittorrent

Which of the following services is not NOT provided by TCP?

Congestion control

Reliable transport

Flow control

Minimum throughput

Minimum throughput

Which of the following services is provided by UDP?

Congestion control

Best-effort service

Flow control

Reliable transport

Best-effort service

The HTTP protocol remembers users' browsing history.

True

False

False

Which of the following statements is false about Web caching?

Web cache reduces response time for some client requests.

Web cache improves security.

Web cache reduces traffic on an institution's access link.

Web cache acts as both a client and a server.

Web cache improves security.

Which of the following DNS servers does not belong to the hierarchical DNS structure?

Top-level domain (TLD) server

Local name server

Root name server

Authoritative DNS server

Local name server

Compared to the DNS iterated query, which of the following descriptions about the DNS recursive query is false?

Longer average resolution time

More load at upper levels of hierarchy

Fewer TLD servers cached in local name server

More secure against spoofing attacks

More secure against spoofing attacks

For a video stream application based on DASH (Dynamic Adaptive Streaming over HTTP), which of the following functions is performed by the server?

Measure available bandwidth

Divide video file into chunks

Choose coding rate

Request manifest file

Divide video file into chunks

When a client requests content from a streaming service, the request is often redirected to a Content Distribution Network (CDN) server. Which protocol is primarily responsible for facilitating this redirection?

DNS

HTTP

TCP

DASH

DNS

In BitTorrent, which rule allows a peer to send file chucks to a neighbor that is not sending file chucks to the peer?

Rarest first

Optimistically unchoke

Tit-for-tat

Most first

Optimistically unchoke

The transport layer provides logical communication between

outers

processes

hosts

networks

processes

For a DNS server running on top of UDP, how many sockets does it need to process 10 DNS requests from 5 clients?

5

10

1

2

1

A Web server running over TCP uses the same socket to handle incoming requests from different clients, provided they are requesting the same URL.

True

False

False

Which of the following is NOT an advantage of UDP over TCP?

No congestion

No connection establishment

No connection state at sender, receiver

Small header size

No congestion

Given two bytes: 11011010 and 01100101, what is the Internet (1's complement) checksum of the two bytes?

1100 0000

0011 1111

0100 0000

1011 1111

1011 1111

Which of the following errors is not handled by TCP?

Routing loops

Transmission errors

Packet losses

Duplicate packets

Routing loops

Which of the following techniques is not used by TCP to handle potential errors?

Timer

Sequence number

Forward error correction

Acknowledgement

Forward error correction

Consider a transmission channel using the stop-and-wait protocol. Assume that the packet length L is 10,000 bits, the channel bandwidth is 10x106 bps, and the round trip time RTT of the channel is 9x10-3 second. Calculate the channel utilization.

0.01

0.1

0.001

1

0.1

What will happen when a timer expires in the go-back-N pipelined protocol?

Retransmit the packet associated with the expired timer

Do nothing

Retransmit all packets in the window

Retransmit the oldest packet in the window

Retransmit all packets in the window

Assume that the window size of the selective repeat pipelined protocol is 3. How many sequence numbers are necessary for the protocol to work properly?

6

5

4

3

6

Which of the following is NOT a feature of TCP?

Pipelined transmission

No transmission errors

Flow control

Full duplex data transfer

No transmission errors

Which of the following fields is NOT in the TCP header?

Acknowledgement number

Receive window size

Congestion window size

Sequence number

Congestion window size

Which of the following TCP header flags is set when establishing a TCP connection?

RST

FIN

PSH

SYN

SYN

Which of the following is NOT a consequence of congestion?

Flipped bits

Wasted upstream transmission capacity

Packet losses

Long delays

Flipped bits

TCP congestion control utilizes information from

network administrators

routers

end systems

switches

end systems