Networking Fundamentals (1)

Question 1

What is a network

Answer 1

Two or more computers connected together

Computers can be any type of computing device (IPSO)

Can be wired or wireless

Question 2

Why have a network?

Answer 2

Share data, remote communication, share resources, such as printers, DBs

Question 3

How computers communicate on a network, what is needed on both sides?

Answer 3

Applications that wish to communicate with one another
Common protocol
Network Interface to connect to network
Transmission media (wired/wireless)

Diagrams page19

Question 4

Client / Server communication

Answer 4

Client initiates the connection
Server waits for clients to connect (has the option to accept or deny)

Question 5

Explain P2P connections

Answer 5

No dedicated server, both clients act as client and server

Question 6

What is an IP Address

Answer 6

Number that identifies a node on the network

e.g.
IPv4 - 192.168.1.10
IPv6 - 2601:140:8780:43f0:2d1e:9ebb:92f0:d6e9

Question 7

Explain MAC Addresses

Answer 7

Physical address of the network interface
Cannot be changed and is assigned by the NIC vendor

Question 8

Unicast

Answer 8

Data being sent to one device

Question 9

Multicast

Answer 9

One to some

Question 10

Broadcast

Answer 10

One to all

Question 11

What is a protocol

Answer 11

Set of rules or “language” for communication
A host will use several protocols to make a connection on the network

Question 12

What is a port

Answer 12

Number that represents an application on the network

Question 13

What is a socket

Answer 13

A port that is in use
Unique combination of protocol, IP address and port

Question 14

Provide an example of a socket

Answer 14

TCP 192.168.1.5:80

Question 15

How many layers in the OSI Model

Answer 15

7

Question 16

OSI Model layer 1

Answer 16

Physical

Question 17

What is Protocol Data Unit (PDA)?

Answer 17

Specific block of information transferred over a network

Question 18

PDU OSI Layer types

Answer 18

◦ Application = data
◦ Presentation = data
◦ Session = data
◦ Transport = segment (TCP), datagram (UDP)
◦ Network = packet
◦ Data Link = frame
◦ Physical = bit

Question 19

OSI Layer 7 : Application Layer

Answer 19

The application itself, where users are typically provided a gui

A protocol is agreed on
e.g. SMTP, HTTP, RDP, TFTP, etc.

Question 20

Layer 6 : Presentation

Answer 20

Both sides agree on a common data format, application might request a browser plugin to be installed here
e.g. JPG, MP3, MP4, PDF, etc.

Question 21

Layer 5 : Session

Answer 21

Keeps seperate conversation seperate
Ports are usually assigned to the conversation

Question 22

Layer 4 : Transport

Answer 22

TCP / UDP Utilised

TCP:
Breaks up data into manageable pieces for transmission
◦ Adds sequence numbers to each segment for reassembly at other end
◦ Embeds the source and destination ports into its header
◦ Establishes the session with a handshake
◦ Provides error correction and flow control during session
◦ Tears down session with a handshake

UDP:
◦ Embeds the source and destination ports into its header
◦ Depends on the application for session establishment, management, payload length, error correction,
flow control, and tear down

Question 23

Layer 3 : Network

Answer 23

Adds a logical address, usually IP address
Chooses optimal route

Question 24

Layer 2 : Data Link Layer

Answer 24

Adds a physical source and destination address
Adds both a header and trailer
Checks incoming frames for errors, cyclical redundancy check (CRC)

Question 25

What are Layer 2s Two Sub Layers

Answer 25

Logical Link Control (LLC) : Describes the layer 3 payload Media Access control (MAC) : Adds the physical address

Question 26

Layer 1 : Physical

Answer 26

Actual transmission of 1s and 0s All electrical and mechanical aspects of transmission e.g. Hubs, repeaters, rj45 connectors

Question 27

Data encapsulation and Decapsulation

Answer 27

Encapsulation Layers 4, 3, 2 on the sender add a header ◦ Description of the data and/or protocol ◦ Layer 2 also adds a trailer Decapsulation: Corresponding layers on the receiver remove the header ◦ Refer to the information in the header/trailer ◦ Pass the PDU up to the next layer

Question 28

OSI Encapsulation / Decapsulation Diagram page

Answer 28

Page 55

Question 29

What is the DoD Model

Answer 29

Developed by the US department of defense 4 Layer model Referred to as TCP/IP Model

Question 30

DoD Model Layers (Top to bottom)

Answer 30

Application, Host to Host, Internet, Network Access

Question 31

DoD Model core protocols

Answer 31

TCP,UDP,IP,ICMP,IGMP,ARP

Question 32

Which is the only protocol in the DoD that doesn't have an IANA assigned protocol number?

Answer 32

ARP

Question 33

DoD Model Application Layer Contains

Answer 33

Data Payload

Question 34

DoD Model Host to Host Layer Contains

Answer 34

Session establishment / Management Sequencing

Question 35

DoD Model Internet Layer Contains

Answer 35

Logical Addressing Routing

Question 36

DoD Model Network Access Layer Contains

Answer 36

Physical addressing, Framing/CRC/MTU Actual Transmission

Question 37

Purpose of a connection oriented protocol

Answer 37

Attempts to ensure reliability and completeness Typically found used in application like video games

Question 38

Purpose of a connectionless protocol

Answer 38

Makes no attempt to ensure completeness of transmission Typically found in application like streaming services

Question 39

Connection Oriented vs Connectionless Protocols P63 for diagram

Answer 39

Connection Oriented: TCP Connectionless: UDP, IP, ICMP, IGMP, ARP

Question 40

What is the difference between connection oriented vs connectionless when regarding performance

Answer 40

Connection oriented prioritises reliability whereas connectionless goes for speed/performance

Question 41

TCP Flags

Answer 41

URG, ACK, PSH, RST, SYN, FIN

Question 42

What does each TCP Flag mean

Answer 42

URG: Tells receiver to prioritise the data ACK: Acknowledge PSH: Tells receiver to directly send this data to the application RST: Tells receiver that the sender has abruptly ended the connection SYN: Used in 3way handshake to start conversation FIN: Used in the 4way handshake to end the conversation