Bits & Bytes: Week 3, I - Transport Layer

Question 1

Gathering data from multiple application processes of sender, enveloping that data with header and sending them as a whole to the intended receiver

Answer 1

Multiplexing

Question 2

Delivering received segments at receiver side to the correct app layer processes

Answer 2

Demultiplexing

Question 3

A 16-bit number that’s used to direct traffic to specific services running on a networked computer

Answer 3

a Port

Question 4

What is the traditional HTTP port on a computer?

Answer 4

Port 80

Question 5

A program running on a computer whose job is waiting to be asked for data

Answer 5

A server or service

Question 6

What is the general term for the following:

10.1.1.100:80

Answer 6

A socket number or socket port

Question 7

ACRONYM:

FTP

Answer 7

File Transfer Protocol

Question 8

Which port is used to connect to an FTP server?

Answer 8

Port 21

Question 9

What encapsulates an IP Datagram?

Answer 9

An ethernet frame

Question 10

What encapsulates a TCP segment?

Answer 10

an IP datagram

Question 11

What is the equivalent of an IP Datagram or Ethernet frame in the Transport Layer?

Answer 11

a TCP segment

Question 12

What part of the TCP header contains the port number of the service the data is being sent to? How many bits?

Answer 12

The destination port field; 16 bits

Question 13

What part of the TCP header is a high numbered port chosen from a special section of ports known as ephemeral ports? How many bits?

Answer 13

The source port field; 16 bits

Question 14

When a web server replies, it is this part of the TCP header’s job to send the data to the correct program (for example, a browser instead of a wifi printer)

Answer 14

The source port field

Question 15

This part of the TCP header is a number that keeps track of where in a sequence of TCP segments this segment is supposed to be. How many bits?

Answer 15

the Sequence number; 32 bits

Question 16

This part of the TCP header is a number that represents the following segment to the current one.. How many bits?

Answer 16

the Acknowledgement number; 32 bits

Question 17

How many bytes can be sent in an ethernet frame?

Answer 17

1518 bytes

Question 18

What part of the data offset field of the TCP header communicates the length of the header so the receiving device knows when the data payload begins? How many bits?

Answer 18

the Header Length Field; 4 bits

Question 19

What are the two parts of a TCP Segment?

Answer 19

The TCP Header and the data section

Question 20

How many TCP control flags are there in a TCP segment?

Answer 20

There are 6; making up a 6 bit field

Question 21

TCP protocol is very reliant on ________________ to make sure everything is being received

Answer 21

Acknowledgements

Question 22

What part of the TCP segment contains the range of a sequence of numbers that might be sent before the receiver needs to return an acknowledgement? How many bits?

Answer 22

The window; 16 bits

Question 23

What follows the window in a TCP segment?

Answer 23

The checksum

Question 24

What is the checksum checking?

Answer 24

The checksum checks to make sure all of the data in a segment made it to the destination without data loss or corruption.

Question 25

What 2 parts of the TCP segment are rarely, if ever, used? How many bits are they each?

Answer 25

the Urgent field and the Options field; 16 bits each

Question 26

What is the field that immediately precedes the payload of a TCP segment?

Answer 26

The padding field

Question 27

Which field of the TCP segment ensures that the data payload begins at the expected location?

Answer 27

The padding field

Question 28

What is in the padding field?

Answer 28

a sequence of zeros

Question 29

What field is mostly not used except for in very complicated control protocols?

Answer 29

The Urgent Field

Question 30

How many TCP control flags are there?

Answer 30

6

Question 31

A value of one (1) in this TCP Control flag area indicates that the segment is considered urgent

Answer 31

URGent

Question 32

As a protocol, _____ establishes connections used to send long chains of segments of data. ______ and _____ just send individual packets of data.

Answer 32

TCP; IP; Ethernet

Question 33

A value of one (1) in this TCP Control flag area indicates that the acknowledgement field should be examined

Answer 33

ACKnowledgement

Question 34

this TCP Control flag area indicates that the transmitting device wants the receiving device to push currently buffered data to the application on the receiving end as soon as possible

Answer 34

PuSH

Question 35

This TCP control flag area indicates that the data hasn't been transmitted correctly and the data transfer for this TCP segment (or segments) needs to start over

Answer 35

ReSeT

Question 36

this TCP Control flag area indicates that the receiving device needs to examine the sequence number field

Answer 36

SYNchronize

Question 37

this TCP Control flag area indicates that all data has been transmitted and the connection can now be closed

Answer 37

FINish

Question 38

When a connection is going to be closed, one device sends a FIN flag of which the other device signals receipt with an ACK flag, and then the other device sends its own FIN flag of which the first device signals receipt with an ACK flag. What is this process called?

Answer 38

the Four-way Handshake

Question 39

When establishing a connection, a device sends a SYN flag to which a receiving device sends ACK/SYN flags in response. The originating device sends an ACK flag. This SYN, SYN/ACK, ACK exchange is known as...

Answer 39

the Three-way Handshake

Question 40

In computer networking, a ________ is how two devices ensure they are speaking the same protocol and will be able to understand eachother

Answer 40

handshake

Question 41

Upon receipt of a data segment over a TCP connection, what is always sent as a response?

Answer 41

A segment with an ACK flag

Question 42

This is the instantiation of an endpoint in a potential TCP connection

Answer 42

a Socket

Question 43

This is the actualization of something defined elsewhere; the creation of an instance of an abstraction

Answer 43

Instantiation

Question 44

This TCP socket state means that a TCP socket is ready and waiting for incoming connections

Answer 44

LISTEN

Question 45

This TCP socket state means that a synchronization request has been sent but the connection hasn't been established yet

Answer 45

SYN_SENT

Question 46

This TCP socket state means that a socket previously in a LISTEN state has received a synchronization request and sent a SYN/ACK flag back.

Answer 46

SYN_RECEIVED

Question 47

This TCP socket state means that a TCP connection is in working order and both sides are free to send each other data

Answer 47

ESTABLISHED

Question 48

This TCP socket state means that a FIN flag has been sent but a corresponding ACK has not been received yet

Answer 48

FIN_WAIT

Question 49

This state means that the connection has been closed at the TCP layer but that the application that opened the socket hasn't release its hold on the socket yet

Answer 49

CLOSE_WAIT

Question 50

This TCP socket state means that the connection has been fully terminated and no further communication is possible.

Answer 50

CLOSED

Question 51

LISTEN is a TCP socket state found on the client or server side?

Answer 51

Server side

Question 52

SYN_RECEIVED is a TCP socket state found on the client or server side?

Answer 52

Server side

Question 53

ESTABLISHED is a TCP socket state found on the client or server side?

Answer 53

Both client and server sides

Question 54

FIN_WAIT is a TCP socket state found on the client or server side?

Answer 54

Both client and server sides

Question 55

CLOSE_WAIT is a TCP socket state found on the client or server side?

Answer 55

Both client and server sides

Question 56

CLOSED is a TCP socket state found on the client or server side?

Answer 56

Both client and server sides

Question 57

SYN_SENT is a TCP socket state found on the client or server side?

Answer 57

Client side

Question 58

This type of protocol establishes a connection and by its standards, ensures that all data has been properly transmitted

Answer 58

Connection-Oriented Protocol

Question 59

Is TCP a connection-oriented or connectionless protocol?

Answer 59

TCP is a connection- oriented protocol

Question 60

How does TCP ensure that data that has been resent due to errors at lower levels is able to be assembled in the correct order?

Answer 60

Sequence Numbers

Question 61

Is UDP a connection-oriented or connectionless protocol?

Answer 61

UDP is a connectionless protocol

Question 62

This type of transfer protocol simply sends a packet of data without creating a connection with a stream of acknowledgements

Answer 62

Connectionless Protocol

Question 63

This protocol is more reliable but can require a lot of bandwidth; this protocol is less reliable but can send higher quality data packets because it requires less bandwidth

Answer 63

TCP (connection-oriented); UDP (connectionless)

Question 64

What is an example of data transfer using UDP?

Answer 64

Streaming video

Question 65

How many bits are used to represent a port?

Answer 65

16 bits

Question 66

What is the range of numbers that can be assigned to ports?

Answer 66

0-65535

Question 67

What port number isn't used for network traffic but can be used for communication between different programs on the same device?

Answer 67

Port 0

Question 68

What is the range of numbers used to represent system ports?

Answer 68

1-1023

Question 69

What is another term for system ports?

Answer 69

Well-known ports

Question 70

What is the range of numbers used to represent registered ports?

Answer 70

1024-49151

Question 71

What is the range of numbers used to represent ephemeral ports?

Answer 71

49152-65535

Question 72

What is another term for ephemeral ports?

Answer 72

Private Ports

Question 73

This kind of port is considered the official port for most well-known network services.

Answer 73

System, or Well-known, Ports

Question 74

This kind of port is used for less common network services

Answer 74

Registered Ports

Question 75

This kind of port is unregistered, generally used for establishing outbound connections, and assigned to the client for just one connection

Answer 75

Ephemeral, or private, ports

Question 76

This is the primary way to stop unwanted traffic from entering a network

Answer 76

Firewalls

Question 77

In which TCP/IP model layer is a firewall most often used?

Answer 77

The transportation layer

Question 78

At the transportation layer, _______ are configured to block traffic to certain ports while allowing traffic to other ports

Answer 78

Firewalls

Question 79

Firewalls block ranges of IP addresses at the __________ layer,

Answer 79

Network