week 11

Question 1

what is the application layer

Answer 1

• -> The application layer is the closest to the user
• -> Provides interface between the applications we use to communicate and underlying network over which our messages are transmitted
• -> application layer protocols are used to exchange data between source and destination hosts

Question 2

what are the 3 functions of the presentation layer

Answer 2

–> formats data from the source device into a compatible form for receipt by the destination device

–> compression of data in a way that can be decompressed by the destination device

–> Encryption of the data for transmission and the decryption of data upon receipt by the destination

Question 3

what are the functions of the session layer

Answer 3

• -> creates and maintains dialogs between source and destination applications
• -> Handles the exchange of information to initiate dialogs, keep them active and to restart the session s

Question 4

what is DNS

Answer 4

used to resolve internet names to ip addresses

Question 5

what is telnet

Answer 5

a terminal emulation protocol used to provide remote access to servers and networking devices

Question 6

what is DHCP

Answer 6

used to assign ip address, subnet mask, default gateway and DNS server to a host

Question 7

what is HTTP used for

Answer 7

used to transfer flies that make up webpages of the world wide web

Question 8

what is FTP

Answer 8

used for interactive file transfer between systems

Question 9

what is trivial file transfer protocol (TFTP)

Answer 9

used for connectionless active file transfer

Question 10

what is simple mail transfer protocol

Answer 10

used for transfer of mail messages and attachments

Question 11

what is post office protocol (POP)

Answer 11

used by email clients to retrieve mail from a remote server

Question 12

what is internet message access protocol (IMAP)

Answer 12

another protocol for email retrieval

Question 13

every connected end device are considered _________ in the p2p network

Answer 13

equal

Question 14

what is a peer in peer to peer networks

Answer 14

it is the end devices

Question 15

what do peer networks do with the resources on the network

Answer 15

peer to peer networks decentralize the resources on a network

instead of locating the data to be shared on dedicated servers, data can be located anywhere and on any connected device

Question 16

what do p2p applications do instead of using a central database

Answer 16

The devices on the network each tell the others what files are available when queried, and use the file sharing protocol and services to support locating resources

Question 17

what are some common p2p applications

Answer 17

• -> edonkey
• -> eMule
• -> BitTorrent
• -> Bitcoin
• -> LionShare

Question 18

in a client server architecture in addition to actual data transfer what else is required

Answer 18

user authentication

identification of file data

Question 19

what protocols does HTTP specify

Answer 19

request and response protocol

Question 20

what are 3 common request message types in HTTP

Answer 20

GET
POST
PUT

Question 21

SMTP used to __________

Answer 21

send mails

Question 22

_________ and __________ used to retrive mail

Answer 22

POP and IMAP

Question 23

SMTP transfers mail reliably and efficiently to ___________–

Answer 23

destination email server

Question 24

describe how SMTP works

Answer 24

• -> transfers mail
• -> SMTP processes must be running on both client and server
• -> message and message header must have a properly formatted recipient email address and a sender
• -> uses port 25

Question 25

what is post office protocol

Answer 25

- -> enables a workstation to retrieve mail from a mail server - -> mail is downloaded from the server to the client and then deleted on the server - -> uses port 110

Question 26

what is Internet Message Access Protocol

Answer 26

- -> another protocol that is used to retrieve email messages - -> unlike POP, when the user connects to an IMAP capable server copies of the message are downloaded to the client application - -> original messages are kept on the server until manually deleted - -> port 143

Question 27

why were domain names created

Answer 27

domain names were created to convert the numeric IP addresses into a simple, recognisable, and easy to remember name

Question 28

the domain name system was created for ________________-

Answer 28

domain name to address resolution

Question 29

what does DNS use to resolve the names associated with these numbered IP addresses

Answer 29

distributed set of servers

Question 30

what system does a DNS protocol use and why

Answer 30

Hierarchical system is used to create a database to provide name resolutino this system looks like inverted tree

Question 31

DNS relies _________ to store and maintain records

Answer 31

decentralised servers

Question 32

what is EACH DNS server responsible for

Answer 32

-->maintains a specific database file and is responsible for managing name to IP mappings for that small portion of the entire DNS structure

Question 33

give some examples of top level domains

Answer 33

.au .com .jp

Question 34

what is Dynamic Host Configuration Protocol

Answer 34

--> automatically assigns IP addresses, subnet masks, gateway and other IP networking parameters to network devices -->When the DHCP server is contacted and an address is requested, the DHCP server chooses an address from a configured range of addresses called a pool and assigns it to the host for a set period. This is why DHCP assigned addresses are not permanent --> DHCP can pose a security risk because any device connected to the network can receive an address

Question 35

what are the 4 DHCP steps

Answer 35

DHCP discover DHCP offer DHCP request DHCP Ack

Question 36

how does an FTP client applicaiton push and pull data from a server

Answer 36

by running FTP daemon

Question 37

what are the 2 connections that the client establishes in FTP

Answer 37

--> the client establishes the first connection to the server for control traffic, consisting of client commands and server replies --> The client establishes the second connection to the server for the actual data transfer `