Introduction to IP

Question 1

What two protocols are in IP?

Answer 1

TCP and UDP

Question 2

What do we say is encapsulated within IP?

Answer 2

TCP and UDP

Question 3

What is a common use for TCP and UDP?

Answer 3

moving data from one part of the network to another`

Question 4

Where might TCP and UDP operate?

Answer 4

at the transport layer of the OSI model (sometimes OSI Layer 4)

Question 5

What do TCP and UDP provide that IP does not?

Answer 5

multiplexing;

allows many diff apps to simultaneously communicate to a separate server

Question 6

What does TCP stand for?

What is another name for it:?

Answer 6

transmission control protocol

connected oriented protocol

Question 7

Describe how TCP works?

Answer 7

requires a formal connection setup and close (3-way handhake: SYN > SYN ACK > ACK RECEIVED)

handshake allows user to know data was verified as received, so delivery is considered “reliable”

can reorder messages that were received out of order

can retransmit data if no SYN ACK received

has a flow control mechanism to allow user to manage how much data is being sent

Question 8

What does UDP stand for?

another name?

Answer 8

user datagram protocol

connectedless protocol

Question 9

Why is UDP considered unreliable?

Answer 9

there is no formal connection made so there is also no acknowledgement of data being received
(thus no reordering of data or retransmissions)

Question 10

What protocol does not have flow control?

Answer 10

UDP

Question 11

What protocol is faster and is associated with real-time communication?

Why is it faster?

Answer 11

UDP

a formal connection does not have to be made between devices before data can be sent

Question 12

What is an example of a connectionless form of communicating?

What are two protocols that use this form?

Answer 12

UDP

dynamic host configuration protocol (DHCP)
trivial file transfer protocol (TFTP)

Question 13

What is DHCP used for?

Answer 13

assigns IP addresses to our devices

Question 14

What is TFTP used for?

Answer 14

used to transfer files using UDP

Question 15

In UDP communication using DHCP, who is responsible for making sure info is received on the other side?

Answer 15

the app, DHCP

Question 16

What is an example of a connection oriented communication?

What are two protocols that use this form?

Answer 16

TCP

hypertext transfer protocol secure (HTTPS)
secure shell (SSH)

Question 17

What does SSH do for the user?

Answer 17

provides an encrypted form of terminal communication between our systems

Question 18

Who take responsibility is a packet was not received in a connection oriented communication?

Answer 18

TCP takes responsibility and resends missing packet based on what SYN ACK was not received

Question 19

To complete the traffic flow between devices, what info do we need?

Answer 19

we need the servers IP address, a protocol (such as TCP or UDP), server application port number for that protocol

we also need the client IP address, protocol being used, associated port number with protocol being used

Question 20

What are non-ephemeral ports?

Answer 20

permanent port numbers that are well known on the server (for ex; want to communicate with a web server, we know that the web server commonly uses TCP port 80)

commonly ports 0-1023, but can be anything

Question 21

What is port 80 commonly associated with?

Answer 21

HTTP

Question 22

What is port 443 commonly associated with?

Answer 22

HTTPS

Question 23

What is a ephemeral port number?

Answer 23

temporary port number used by client when communicating with server

commonly assigned port 1,024 - 65,535

Question 24

What are port numbers basically used for?

Answer 24

communication (not security)

Question 25

Are TCP and UDP port numbers the same?

Answer 25

no

you can have a service running on TCP port 80 and another service running on UDP port 80 (not done in normal operation to avoid confusion)

Question 26

When communicating between client and server, whose port number is random?

Answer 26

the client source port number