Midterm-Fall 2020 (Covers chapter 1 to chapter 4)

A datagram with size 3030 bytes passes through a network with MTU 1020 bytes, how many fragments will be generated?

a. 1

b. 2

c. 3

d. 4

ans: d

For a network link with bandwidth 1 Mb/s, each user can use 200 kb/s when "active" with 10% of time. If packet switching is used, at most how many users can share this link to transfer information?

a. 5

b. 10

c. 15

d. there is no limit theoretically

ans: d

Which one is not a protocol?

a. TCP

b. IP

c. DNS

d. Transport

ans: d

A given IP address in CIDR format is 212.26.208.6/19, what is its network prefix?

a. 212.26.208.0

b. 212.26.192.0

c. 212.26.128.0

d. 255.255.255.0

ans: b

How long does it take to send a file of 128 kbits from host A to host B over a circuit-switched network? Suppose the following,

1. All links are 1536 kbps

2. Each link uses TDM with 48 slots/sec

3. 500 millisecond to establish end-to-end circuit

a. 1.5s

b. 3.5s

c. 4.5s

d. 10.5s

ans: c

Two network links have L1: 1.2Mbps and L2: 2.3Mbps bandwidth, respectively. L1 and L2 use the same media. If we use L1 and L2 to transfer the same file myData.dat from Host A to Host B, respectively, which link will use more propagation time (suppose no routers are in between)?

a. L1

b. L2

c. the same

d. undecided

ans: c

Which of the following is a purely typical client-server model?

a. Skype

b. BitTorrent

c. Google email system

d. Instant Messaging

ans: c

If a client sends a HTTP request through a non-persistent HTTP connection to request 8 jpeg images, assuming the time to set up the connection is the same as the time to request a jpeg image, 150ms, and the time to transfer each image is 100ms, how much time will the client need to obtain all 8 images?

a. 2000ms

b. 3000ms

c. 2800ms

d. 3200ms

ans: d

If we want to send many files with the same size 128 kbits from host A to host B over a circuit-switched network? Suppose the following,

1. The total bandwidth is 1536 kbps

2. Each link uses FDM with 32kbps transfer rate

3. 500 millisecond to establish end-to-end circuit

How many files at most are allowed to be sent concurrently?

a. 48

b. 64

c. 32

d. 12

ans: a

Sending 8000 bits data packet to the receiver side through a link with 1 Gbps bandwidth and 5 ms propagation delay, the utilization is approximately _______.

a. 0.0004

b. 0.0008

c. 0.0005

d. 0.0003998

ans: b

If a user sends information with sequence number from 10 to 110 using SR protocol, how would the sender side set up its window size?

a. 100

b. 200

c. 50

d. 0

ans: c

The protocol DHCP works in ______________ Layer.

a. Application

b. Network

c. Transport

d. IP

ans: a

For a network link with bandwidth 1 Mb/s, each user can use 200 kb/s when "active" with 10% of time. If TDM is used, how many users at most can use this link concurrently?

a. 5

b. 10

c. 15

d. 20

ans: b

Which of the following is not correct for P2P network communication?

a. no always-on server

b. Highly scalable

c. Client must have dynamic IP address

d. Peers are intermittently connected and change IP addresses

ans: c

How to handle a big packet in IPv6?

a. fragment the big packet

b. Test it using ICMP message to see if "packet is too big"

c. ignore the big packet

d. drop the big packet

ans: b

Which application of the following can tolerate data loss, require minimum throughput, and be time sensitive?

a. file transfer

b. email

c. interactive games

d. browse web document

ans: c

Wait for call from above

rdt_send(data)

packet = make_pkt(data)

udt_send(packet)

for the FSM shown in the figure, which description is correct?

a. packet is made at Application Layer

b. packet is made at Transport Layer

c. packet is made at Network Layer

d. packet is made at Data link Layer

ans: b

Two network links have L1: 1.2Mbps and L2: 2.3Mbps bandwidth, respectively. L1 and L2 use the same media. If we use L1 and L2 to transfer the same file myData.dat from Host A to Host B, respectively, which link will use more transmission time?

a. L1

b. L2

c. the same

d. undecided

ans: a

Each process in a host of the Internet is uniquely identified by

a. IP address of the host

b. the port number of the process

c. the IP address of the host and the Port number of the process

d. Host name of the host

ans: c

which statement of the following is correct?

a. twisted pair is a reliable data transmission media

b. optical fiber is a reliable data transmission media

c. Network layer data transfer is not reliable

d. a router is a reliable data transfer device

ans: c

The following is a router forwarding table.Prefix Match _______________ Link Interface 11001000 00010111 00010_______0 11001000 00010111 0001110______111001000 00010111 000111_______2otherwise ______________________3Please determine the interface for the packet with header "11001000 00010111 00011101 11010011 "

a. 0

b. 1

c. 2

d. 3

ans: b

Which statement of the following about cookie technique is correct?

a. a cookie file is kept at the user's host and managed by the server side

b. a cookie file is kept at the user's host and managed by the user's browser

c. a cookie file is kept at the server side, and managed by the user side

d. a cookie file is kept at the server side and managed by the user's browser

ans: b

TCP flow control indicates

a. Sender won't overwhelm receiver

b. Receiver won't overwhelm sender

c. Sender controls suitable bandwidth used

d. Both sender and receiver need to be controlled

ans: a

If a user sends a file from Host A to Host B using TDM, _____ is used in this communication process.

a. Packet-switching

b. Circuit switching

c. Pack and Circuit switching

d. none of them

ans: b

DatagramSocket MySocket = new DatagramSocket(9876);

this statement creates

a. Server side UDP socket

b. Server side TCP socket

c. Client side UDP socket

d. Client side TCP socket

ans: a

If we want to send many files with the same size128 kbits from host A to host B over a circuit-switched network? Suppose the following,

1. The link bandwidth is 1.536 Mbps

2. The link uses TDM with 24 slots/sec

3. 500 millisecond to establish end-to-end circuit

How many files are at most allowed to send concurrently?

a. 32

b. 48

c. 24

d. 16

ans: c

In rdt2.0, rdt_send() is called from

a. transport layer

b. application layer

c. datalink layer

d. network layer

ans: b

Cookie ID is kept at

a. client side only

b. Server side only

c. both server and client sides

d. neither server nor client side

ans: c

Which of the following is correct about Go-Back-N protocol?

a. the value of variable "nextseqnum" must be bigger than the value of "send_base" in the Sending window

b. it maintains one timer for each in-flight packet.

c. the oldest unacked packet in its sending buffer window must be acknowledged first.

d. Unacked packets in its buffer window must not be consecutive.

ans: c

Which one of the following does not belong to the network edge?

a. Google spider

b. Yahoo servers

c. Optical fiber

d. CSU e-mail server

ans: c

if CSU needs to register its own network with domain name "csu.edu" at "EDU" domain, what are the two RRs in "EDU" domain's DNS server database? Assume "CSU" DNS server name is csu-dns, and its ip address is 168.126.167.26.

a. (csu.edu, csu-dns.csu.edu, NS) (csu-dns.csu.edu, 168.126.167.26, A)

b. (csu.edu, csu-dns.csu.edu, MX) (csu-dns.csu.edu, 168.126.167.26, A)

c. (csu.edu, csu-dns.csu.edu, A) (csu-dns.csu.edu, 168.126.167.26, NS)

d. (csu.edu, csu-dns.csu.edu, CNAME) (csu-dns.csu.edu, 168.126.167.26, A)

ans: a

Which of the following methods can upload a file in entity body to a path specified in URL field through HTTP message?

a. GET

b. POST

c. HEAD

d. PUT

ans: d

DASH technique is directly over _______________.

a. SMTP

b. UDP

c. HTTP

d. DNS

ans: c

SMTP uses

a. persistent UDP connection

b. nonpersistent HTTP connection

c. persistent TCP connection

d. persistent UDP connection

ans: c

Which of following uses POP3 protocol?

a. compose an email at client side

b. access emails at client side

c. deliver emails between email servers

d. push email message from client side to server side outgoing queue

ans: b

DatagramSocket MySocket = new DatagramSocket();

the above statement creates

a. client side TCP socket

b. Server side UDP socket

c. client side UDP socket

d. server side TCP socket

ans: c

The reason for the duplicated packets received in rdt2.0 is

a. packet lost

b. sender acknowledgement lost

c. receiver acknowledgement lost

d. acknowledgement corrupted

ans: d

Which one is a guided physical media?

a. Coax

b. Radio

c. Infrared ray

d. Blue ray

ans: a

| Host A Host B

| Seq = 92, 8 bytes data ----------------> <---- ACK = 100

| Seq = 100, 20 bytes data -------------> <------ACK = 120

sendbase

Based on the TCP communication as shown in the figure, what are the values of SendBase?

a. 100

b. 126

c. 120

d. 110

ans: c

The main issue with switching via a bus to forward a datagram from input port to output port of a router is__________.

a. two bus crossing per datagram

b. bus contention

c. high cost

d. inefficient

ans: b

If you compose an email, and send it out, which protocol is used?

a. HTTP

b. SMTP

c. POP3

d. IMAP

ans: b

SMTP protocol is directly carried over _______.

a. UDP

b. TCP

c. IP

d. DNS

ans: b

DNS is

a. Application layer protocol

b. Datalink layer protocol

c. Transport layer protocol

d. Network layer protocol

ans: a

When a network application program is developed,

a. router needs to be considered and programmed

b. only the edge of the network is considered

c. both the core and the edge of the network are considered

d. network layer needs to be considered and programmed

ans: b

Socket is

a. application-created, OS-controlled

b. application-created, application-controlled

c. OS-created, OS-controlled

d. OS-created, application-controlled

ans: a

Which one is the core part of the Internet?

a. Data base server in CSU

b. Google Search engine

c. Router

d. a E-mail server

ans: c

Protocol DNS is used within ______.

a. one AS

b. multiple ASs

c. two ASs

d. the Internet

ans: d

Which of the following is correct about client-server model?

a. Server must have a static IP address

b. Client must have a static IP address

c. Server must have a dynamic IP address

d. Client must have a dynamic IP address

ans: a

If you make a call through MSN or Skype to your friend in another city, how is your voice transferred through the Internet to your friend?

a. via Packet-Switching

b. via Circuit-Switching

c. via Packet and Circuit switching.

d. via Neither Packet or circuit switching

ans: a

For a network link with bandwidth 1 Mb/s, each user can use 100 kb/s when "active" with 10% of time. If FDM is used, how many users at most can use this link concurrently?

a. 5

b. 10

c. 15

d. 20

ans: b