Comp Networks

Question 1

What do packet switches do?

Answer 1

forward packets (chunks of data)

Question 2

give examples of some communication links

Answer 2

Fiber
Copper
Radio
Sattiliete

Question 3

What are networks

Answer 3

collection of devices, routers

Question 4

What are protocols

Answer 4

control sending, receiving of messages

Question 5

How to connect end systems to edge router?

Answer 5

residential access nets
institutional access networks (school, company)
mobile access networks (WiFi, 4G/5G)

Question 6

Give an example of a WLAN

Answer 6

WIFI in home

Question 7

Give an example of wide-area cellular access networks

Answer 7

4G/5G

Question 8

What do data centre networks do?

Answer 8

Connects hundreds. to thousands of servers together and to the internet

Question 9

When does queueing occur

Answer 9

When work arrives faster than it can be serviced

Question 10

What happens if the memory in the router fills up?

Answer 10

packets can be dropped

Question 11

What does FDM stand for?

Answer 11

Frequency Division Multiplexing

Question 12

What does TDM stand for?

Answer 12

Time Division Multiplexing

Question 13

Why are protocols needed for packet switching

Answer 13

reliable data transfer and congestion control

Question 14

Given millions of access ISP’s, how long does it take to connect them together?

Answer 14

O(N^2)

Question 15

How does packet delay occur

Answer 15

Packets queue in router buffers, waiting for turn for transmission

Question 16

what are the cleint and server roles in process communication

Answer 16

Client: process that initiates communications
Server: process that waits to be contacted

Question 17

What is the HTTP port number?

Answer 17

80

Question 18

How many bits are in a IP address

Answer 18

32

Question 19

What transport service does an app need?

Answer 19

Data integrity
Throughput
Timing
Security

Question 20

What does UDP service not provide

Answer 20

reliability, flow control, congestion control, timing, throughput guarantee, security or connection setup

Question 21

What does SMTP stand for and where is it used?

Answer 21

Simple mail transfer protocol
Emails

Question 22

Where is SMTP protocol located?

Answer 22

between mail servers to send email messages

Question 23

What are the three phases of SMTP transfer

Answer 23

SMTP handshaking (greeting)
SMTP transfer of messages
SMTP closure

Question 24

What is the SMTP port number?

Answer 24

220

Question 25

is HTTP stateless

Answer 25

yes

Question 26

What is the difference between persistent and non-persistent HTTP

Answer 26

Persistent: multiple objects can be sent over a single TCP connection between the server and the client Non: only one object

Question 27

What is first party and third party cookies?

Answer 27

First party: tracking user behaviour on a given site Third party: tracking user behaviour across multiple sites

Question 28

Give examples of some DNS services

Answer 28

hostname to ip address translation host aliasing mail server aliasing load distribution

Question 29

Name some features about TCP

Answer 29

reliable, in-order delivery congestion control flow control connection setup

Question 30

Name some features about UDP

Answer 30

unreliable, unordered delivery