Module 14 - TCP and UDP

Question 1

Which protocol is typically used for real-time communication like streaming or IP voice?

Answer 1

UDP (User datagram protocol)

Question 2

Why is UDP preferred in real-time applications?

Answer 2

UDP has minimal overhead , it does not retransmit lost packets so there is no delay

Question 3

What is a major reason UDP is not used in financial transactions?

Answer 3

It is unreliable

Question 3

What does UDP add to each data segment?

Answer 3

Source and destination port numbers

Question 4

What happens to UDP packets if they are dropped or arrive out of order?

Answer 4

Dropped packets are not retransmitted, packets arriving out of order are reordered

Question 5

Which protocol provides reliable delivery with retransmission and sequencing?

Answer 5

TCP (Transmission Control Protocol)

Question 6

How does TCP ensure data reliability? (2)

Answer 6

Adds sequence numbers to packets and uses acknowledgements for received packets.

Question 7

What role do TCP sequence numbers play?

Answer 7

They allow the destination to reassemble the packets in order

Question 7

What happens if a TCP packet is not acknowledged?

Answer 7

It is retransmitted

Question 7

In TCP, what is the “window size”?

Answer 7

Number of packets sent before an acknowledgement.

Question 8

How does TCP adjust window size in reliable vs unreliable networks?

Answer 8

It increases window size in reliable networks and decreases window size in unreliable

Question 9

Which protocol includes constant communication between source and destination to regulate transmission?

Answer 9

TCP

Question 9

Give an example of a TCP port used in web browsing.

Answer 9

Port 80 HTTP

Question 9

What kind of application would likely use UDP instead of TCP?

Answer 9

Online gaming, streaming, VoIP

Question 10

What is the key disadvantage of TCP compared to UDP?

Answer 10

TCP has high overhead due to reliability features

Question 11

In TCP, what triggers retransmission of lost packets?

Answer 11

Lack of acknowledgement of a sequence

Question 12

Why is delay from retransmission unacceptable in UDP-based communication?

Answer 12

It disrupts real time experience like live video or audio.

Question 13

Which protocol is connection-oriented?

Answer 13

TCP

Question 14

Which protocol is considered connectionless?

Answer 14

UDP

Question 15

Which layer of the OSI model uses port numbers to identify applications?

Answer 15

Layer 4, transport layer

Question 15

What is the function of transport layer port numbers?

Answer 15

To identify source and destination applications

Question 16

What is a “well-known port”?

Answer 16

Port numbers of well known network applications from 1-1023

Question 17

Which organization manages port number assignments?

Answer 17

ICANN (Internet corporation for assigned names and numbers)

Question 18

What port number does HTTP use?

Answer 18

TCP port 80

Question 19

Which well-known port is used for FTP control?

Answer 19

TCP port 21

Question 20

What port number is used by a mail server with SMTP?

Answer 20

TCP port 25

Question 21

Which port range is typically used for dynamically assigned source ports?

Answer 21

Ports Above 1024

Question 22

What port range is categorized as "Private Ports"?

Answer 22

Ports 49152 to 65535

Question 23

What port range is categorized as "Registered Ports"?

Answer 23

Ports 1024 to 49151

Question 24

What is a “socket” in networking?

Answer 24

A combination of and IP address and a port number

Question 25

What is a "socket pair"?

Answer 25

A combination of source and destination socket in a connection

Question 26

Give an example of a client socket.

Answer 26

192.168.1.3:1026 (IP address and dynamic port)

Question 27

Give an example of a server socket.

Answer 27

192.168.6.8:25 (IP address and well known port)

Question 27

How can multiple applications run on the same client simultaneously?

Answer 27

Each application uses a dynamically assigned source port

Question 28

Which port is used by DNS requests from clients?

Answer 28

UDP port 53

Question 29

Which port does the TFTP protocol use?

Answer 29

UDP port 69

Question 30

Which command is used to check current TCP connections on a host?

Answer 30

netstat

Question 31

Which option Displays IP addresses and port numbers in numerical form in netstat?

Answer 31

netsat -n