Midterm

Question 1

T/F - UDP Protocol implements RDT.

Answer 1

False - unreliable, connectionless transport layer service

Question 2

T/F - A Network is a system for connecting multiple computers using a single transmission technology.

Answer 2

True

Question 3

Which delay is occurs during transit time between nodes?

Answer 3

Propagation Delay

Question 4

What is the internet?

Answer 4

A computer network that interconnects computing devices.

Question 5

What devices reside in the network core?

Answer 5

Routers, Packet Switches

Question 6

What devices reside in the network edge?

Answer 6

PCs, Printers, Smart Phones, Servers, etc.

Question 7

What is a Time-Division Multiplexing (TDM) link?

Answer 7

A link of a circuit-switched network that divides up connections based on time (e.g. 0.1ms alotted to connection #1 of 10).

Question 8

What is a Frequency-Division Multiplexing (FDM) link?

Answer 8

Used in circuit-switched networks, it divides up the connections of a link across the frequency (hz) spectrum.

Question 9

What is a silent period in a circuit-switched network?

Answer 9

If a connected user is not using their allotted bandwidth.

Question 10

T/F - the internet is a network of networks.

Answer 10

True.

Question 11

Is the internet core packet-switched or circuit-switched?

Answer 11

Packet-switched

Question 12

What is a store-and-forward network?

Answer 12

A packet switch must receive the full packet before transmitting out.

Question 13

Signal Attenuation effects _____ more than _____.

Answer 13

Unguided Media / Guided Media

Question 14

At the transport layer, what is the payload?

Answer 14

Application data

Question 15

Which layer is responsible for finding the destination IP address?

Answer 15

Application Layer

Question 16

What are the 7 layers of OSI layering model?

Answer 16

Layer 7 = Application Layer
Layer 6 = Presentation Layer
Layer 5 = Session Layer
Layer 4 = Transport Layer
Layer 3 = Network Layer
Layer 2 = Link Layer
Layer 1 = Physical Layer

Question 17

What is packet spoofing?

Answer 17

Using someone else’s IP address to send info into the internet.

Question 18

What is multiplexing?

Answer 18

Merging multiple communications streams into the same media.

Question 19

A paired ip address and port number is called a _____.

Answer 19

Socket

Question 20

What are some application-layer protocols?

Answer 20

Telnet, FTP, POP3, DNS, SSH

Question 21

Protocol ________ allows multiple protocols to work together.

Answer 21

Interoperability

Question 22

Which endian has smallest byte first?

Answer 22

Little Endian… 6F4A is written as 4A6F

Question 23

Which endian representation is used for network comms?

Answer 23

Big Endian.

Question 24

A pair of sockets is called a __________.

Answer 24

Connection

Question 25

Live-streaming video would likely use ____ as its transport layer protocol.

Answer 25

UDP

Question 26

What is the reserved port for HTTP?

Answer 26

Port 80.

Question 27

What are the two pull protocols for email?

Answer 27

POP3 and IMAP

Question 28

What does HTTP utilize for caching?

Answer 28

Conditional GET

Question 29

Does an FTP server maintain client states?

Answer 29

Yes

Question 30

Reserved port for SMTP

Answer 30

25

Question 31

What are two FTP ports?

Answer 31

Control port = 21. Data port = 20.

Question 32

Transport layer manages communications from _____ to _____.

Answer 32

Process to Process

Question 33

HTTP implements caching using a _____ protocol check.

Answer 33

TCP

Question 34

Network layer manages communications from ________ to ________?

Answer 34

Host to Host

Question 35

What is TCP Receiver Action after receiving an in-order segment with expected sequence number. All data up to seq num allready ACK'd?

Answer 35

Delayed ACK. Wait up to 500ms for next segment. If next segment doesn't arrive, send ACK.

Question 36

What is min and max TCP header size

Answer 36

20 BYTES/ 60 BYTES

Question 37

What is maximum UDP Header size?

Answer 37

8 bytes

Question 38

What ACK scheme has ACKs that only verify the ACK'd segment?

Answer 38

Selective Acknowledgement Scheme

Question 39

What ACK scheme has ACK's that verify all segments prior to the ACK'd segment have been received?

Answer 39

Cumulative Acknowledgement Scheme

Question 40

A TCP fast-retransmit will occur after....

Answer 40

3 duplicate ACK's received for the same segment

Question 41

What is sequence of events for closing a TCP Connection?

Answer 41

Client sends segment with FIN bit set. Server responds with ACK. Server sends segment with FIN bit set. Client sends ACK of received segment.

Question 42

What are steps to initializing a TCP connection?

Answer 42

Client send segment with SYN bit set to 1. Server responds with SYN set to 1 and ACK set to Client's SeqNum+1. Server responds with segment of SYN set to 0 and ACK set to Server's SeqNum+1 (this segment can have payload).

Question 43

What is the best transport protocol to push data into the internet?

Answer 43

UDP

Question 44

The TCP sliding window is used to implement ___________.

Answer 44

Flow Control

Question 45

The TCP countdown timer is used to implement ___________.

Answer 45

Reliable Data Transmission

Question 46

What does TCP receiver do if it receives an out-of-order segment with higher than-expected sequence number?

Answer 46

Immediately send duplicate ACK indiciated seq num of next expected byte.

Question 47

What does TCP receiver do if it receives an in-order segment with expected sequence number, with one other in-order segment waiting for ACK?

Answer 47

Immediately send single cumulative ACK, ACK-ing both in order segments.

Question 48

What are fields in the UDP header?

Answer 48

Length, Destination Port, Source Port, Checksum.

Question 49

A _____________ type retransmission will retransmit one segment at a time upon a countdown timer interrupt.

Answer 49

selective retransmission