Lesson 1 - History and Internet Architecture

Question 1

Galactic Network

Answer 1

a 1962 vision of J.C.R Licklider from MIT. He envisioned that everyone could quickly access data through a set of interconnected computers.

Question 2

ARPANET

Answer 2

First network connecting 4 nodes (UCLA, Stanford, UCSB, Univ. of Utah) created by MIT researcher Lawrence Roberts in 1969.

Question 3

DARPA

Answer 3

Defense Advanced Research Projects Agency

Question 4

One of the first application launched on the internet in 1972

Answer 4

email

Question 5

The initial ARPANET Host-To-Host protocol introduced in 1970

Answer 5

Network Control Protocol (NCP)

Question 6

Protocol developed 1973 as an evolution of NCP which introduced the idea of open-architecture networking so that individual networks may be independently designed and developed

Answer 6

TCP/IP

Question 7

TCP original 1973 service features were

Answer 7

The Transmission Control Protocol focused on service features such as flow control and recovery from lost packets.

Question 8

IP originally responsible for

Answer 8

Internet Protocol responsible for addressing and forwarding of individual packets

Question 9

System designed in 1983 to translate domain names to IP addresses by a scaleable distributed mechanism.

Answer 9

Domain Name System (DNS)

Question 10

Application first introduced by team of researchers lead by Tim Berners-Lee

Answer 10

World Wide Web

Question 11

Advantages of internet layered architecture

Answer 11

scalability, modularity, flexibility

Question 12

Disadvantes of layered protocol stack model

Answer 12

1. Some layers’ functionality depends on the information from the other layers.
2. One layer may duplicate lower layer functionalities.
3. Overhead that is caused by the abstraction between layers.

Question 13

OSI model layers proposed by the International Organization for Standardization (ISO)

Answer 13

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

Question 14

Internet Protocol Stack layers are:

Answer 14

1. Application
2. Transport
3. Network
4. Data Link
5. Physical

Question 15

What is the interface between the application and transport layer?

Answer 15

sockets

Question 16

describe the Application Layer

Answer 16

includes multiple protocols (web, email, ftp, DNS) and multiple services.

Question 17

What does the Presentation Layer do?

Answer 17

formats the information that it receives from the layer below and delivering it to the application layer.

Question 18

The Session Layer is responsible for

Answer 18

The session layer is responsible for the mechanism that manages the different transport streams that belong to the same session between end-user application processes

Question 19

In which layer do the TCP and UDP protocols reside

Answer 19

Transport Layer

Question 20

Transport layer packet of information

Answer 20

segment

Question 21

Network layer packet of information

Answer 21

datagram

Question 22

Transport layer is responsible for

Answer 22

end-to-end communication between end hosts.

Question 23

The Network Layer is responsible for

Answer 23

moving datagrams from one Internet host to another.

Question 24

Which layer includes the Internet Protocol (IP) & routing protocols?

Answer 24

Network layer

Question 25

Data Link layer packets of information

Answer 25

frames

Question 26

Protocols in the Data Link Layer

Answer 26

Ethernet, PPP, WiFi

Question 27

Describe the Physical Layer

Answer 27

The physical layer facilitates the interaction with the actual hardware
It is responsible for transferring bits within a frame between two nodes that are connected through a physical link.

Question 28

What responsibility does the data link layer have?

Answer 28

data link layer is responsible to move the frames from one node (host or router) to the next nod

Question 29

define encapsulation with respect to network data

Answer 29

the process of adding layer information to the proceeding layer.
The transport layer encapsulates the application message with a transport header to make a segment.
The network layer encapsulates the segment with network header information to make a datagram.

Question 30

End-to-end principle

Answer 30

the network core should be simple and minimal, while the end systems should carry the intelligence.

Question 31

What is OSI model

Answer 31

A 7-layer internet architecture model proposed by ISO

Question 32

What are examples of a violation of the end-to-end principle?

Answer 32

firewalls, traffic filters, Network address translation box (sometimes home router),

Question 33

What are the ramifications of the hourglass shape of the internet?

Answer 33

A. Many technologies that were not originally designed for the internet have been modified so that they have versions that can communicate over the internet (such as Radio over IP).
B. It has been a difficult and slow process to transition to IPv6, despite the shortage of public IPv4 addresses.

Question 34

What is an EvoArch model?

Answer 34

an abstract model for studying protocol stacks and their evolution.

Question 35

On which layers to repeaters, hubs, bridges, routers operate?

Answer 35

repeaters/hubs - physical layer - receive and forward digital signals to connect different Ethernet segments.
Bridges - Data Link layer (layer 2) Receive packets and forward them to the appropriate destination.
Routers - Network Layer (Layer 3)

Question 36

What is the purpose of the Spanning Tree Algorithm?

Answer 36

The goal of the spanning tree algorithm is to have the nodes (bridges) select which links (ports) to use for forwarding eliminating loops.

Question 37

Describe the steps of the Spanning Tree Algorithm.

Answer 37

The algorithm runs in “rounds” and at every round each node sends to each neighbor node a configuration message with three fields: a) the sending node’s ID, b) the ID of the roots as perceived by the sending node, and c) the number of hops between that (perceived) root and the sending node.

At every round, each node keeps track of the best configuration message that it has received so far, and it compares that against the configuration messages it receives from neighboring nodes at that round.

Question 38

Name each of the 5 internet layer’s packet of information

Answer 38

application - message 
transport - segment, 
network - datagram
data link - frame
physical - ??