4.9.4 TCIP/IP Protocol

Question 1

What is the TCIP/IP Protocol stack and what layers are there?
Remember ATNL

Answer 1

1) A stack of networking protocols that combine as 4 connected layers which pass incoming and outgoing data packets up and down layers of network communication
1) Application Layer
2) Transport Layer
3) Network Layer
4) Link Layer

Question 2

What is the function of the application layer?

Answer 2

1) Top of the stack

2) Uses protocols related to the application to transmit data over a network

Question 3

What is the function of the Transport layer?

Answer 3

1) Uses Transmission control protocol (TCP) to establish and end to end connection with the recipient computer
2) Data is split into packets and labelled with the:

1) Packet number
2) Total number of packets
3) Port number to ensure it is handled by the correct application on the recipient computer

Question 4

What is the function of the Network layer?

Answer 4

1) Adds the source and destination IP addresses
2) Routers use these IP addresses to forward packets to the destination
3) Combining the IP address and the port number forms a socket that specifies the device that the packet is to be sent to and the application being used on that device

Question 5

What is the function of the link layer?

Answer 5

1) Controls physical connections between pieces of hardware in a network, it Adds MAC addresses to packets which it receives from the network layer

Question 6

What is the role of MAC (Media Access Control) addresses?

Answer 6

1) MAC is a unique 12-digit hexadecimal code that is hardcoded on every NIC (Network Interface Card) during the manufacture
2) This uniquely identifies a particular device anywhere in the world so that data packets can be routed directly to them

Question 7

Explain what the FTP protocol is used for (Port 20 and 21)

Answer 7

1) Port 20 and 21
2) Used to transfer files between two computers
3) Used to remotely access a computer/server
4) Transfer files to the server first and then from the server to the recipient’s computer

Question 8

Explain what the SMTP protocol is used for (Port 25)?

Answer 8

1) Port 25
2) Used to send emails from email client to email server
3) Simple Mail Transfer Protocol

Question 9

Explain what the POP3 protocol is used for (Port 110)?

Answer 9

1) Port 110
2) Used to retrieve emails from email servers
3) Automatically remove emails from the server once they are accessed locally

Question 10

Explain what the SSH protocol is used for (Port 22)?

Answer 10

1) Port 22
2) Used for remotely accessing and managing a computer
3) uses public-key encryption that requires a digital certificate to authenticate the user

Question 11

Explain what the HTTP protocol is used for (Port 80)?

Answer 11

1) Port 80

2) Used to hold web pages in text form by a web server which they can deliver to clients

Question 12

Explain what the HTTPS protocol is used for (Port 443)?

Answer 12

1) Port 443

2) Same function as HTTP but encrypts the information during transfer

Question 13

Explain how an FTP client software works in terms of anonymous and non-anonymous access?

Answer 13

1) FTP Software client at the top of the protocol
2) User actions generate FTP commands
3) Files are transferred by dragging from one area to another
4) Most FTP servers require a username and password to access but some sites can be set up for anonymous use without any login details

Question 14

How is SSH used for remote management?

Answer 14

1) uses public-key encryption that requires a digital certificate to authenticate the user
2) Used by network administrators to remotely manage business servers using commands

Question 15

Explain how SSH can be combined with other application-level protocols to create loopholes?

Answer 15

1) Commbinign SSH with other application-level protocols can create a ‘tunnel’ through port 22 where HTTP, POP3 or SMTP requests can operate
2) This allows for network restrictions to be bypassed

Question 16

Explain the role of an email server?

Answer 16

1) Virtual post office
2) POP3 (Post office Protocol) retrieves emails from the mail server which temporarily stores mail
3) It is then transferred to your computer
4) Different devices not synchronized mail
5) IAMP (Internet message access protocol) maintains synchronicity between devices by keeping mail on the mail server
6) SMTP transfers outgoing emails from one server to another

Question 17

Explain the role of a web server in displaying web pages in text form?

Answer 17

1) Web servers host a website that handles client
2) uses HTTP to send content to users

3) Web pages stored as text files that are written in HTML or
JavaScript

4) Browser renders pages accordingly

Question 18

Explain the role of a web server in rendering web pages?

Answer 18

1) The HTTP response consists of
- Text document containing HTML
- CSS for styling
- Java Script to run client-side code

2) This page is parsed and broken down into a standard hierarchical model
- HTML broken down into tags called Document Object model
- CSS form their own CCSOM CSS object model
- Javascript is parsed and executed

3) Browser then renders the page on the screen as the designer intended

Question 19

What is an IP address?

Answer 19

A unique numerical address used to identify a host computer or network node

Question 20

How is an IP address structured?

Answer 20

1) 2 parts to identify the individual network and the host computer
- Network Identifier = First bits in 32-bit address
- Size of the network ID determines the number of bits remaining for the Host ID

Question 21

How many standards of IP address are there?

Answer 21

1) IPv4

2) IPv6

Question 22

Why was v6 introduced?

Answer 22

1) IPv6 was deployed as IPv4 (32 bit) only provides 4 billion address combinations and we are running out of addresses
- 4 blocks divided by dots

2) IPv6 (128 bit) hexadecimal introduced which offers 340 trillion unique addresses
- 8 blocks divided by colons

Question 23

What is a routable IP address?

Answer 23

1) A Public IP address registered under the DNS

Question 24

What is Non-routable IP address?

Answer 24

1) A private IP address used for a device on a private network that is hidden behind a router or firewall

Question 25

What is the purpose and function of DHCP?

Answer 25

1) Used to automatically assign a dynamic IP address from a pool of available addresses to a computer attempting to operate on a public network e.g. a Hotspot
2) DHCP provides the subnet mask and the configuration details for the IP address for those manually configuring
3) Since IPv4 is in short supply computers can request an IP address when they are online and release the address back to the pool for other computers when their not in use

Question 26

What is NAT?

Answer 26

1) NAT is the conversion of a private IP address to a public IP address by modifying address information in the packet header when the packet is sent through router

Question 27

Why is NAT used?

Answer 27

1) NAT is used as private IP addresses are not routable and cannot be used for routing packets on the Internet
2) NAT is used as Private addresses are not unique so external servers cannot send packets directly back to a unique private address
3) Extra layer of security as it automatically creates a firewall between internal and external networks

Question 28

What is Port Forwarding?

Answer 28

1) Process of routing data through additional ports to allow a server in a non-routable network to provide services to the internet

Question 29

What is the Client-Server Model?

Answer 29

1) In the client-server model a client sends a request message to a server which should respond with the data requested or a suitable response
2) E.g. client browser sends an HTTP request to a web server

Question 30

What is the WebSocket protocol

Answer 30

1) An example if an API Web socket is a modern application layer that facilitates a persistent bi-directional communication channel between the client and the server which allows them to send data at any time
2) Packets are smaller less header information and travel faster they are automatically accepted at either end without security checks
3) E.g. In Online gaming, instant messaging or remote collaboration

Question 31

What does the CRUD acronym stand for?

Answer 31

CRUD = Create-Retrieve-Update-Delete

Four fundamental operations for any database or content

Question 32

What is REST?

Answer 32

1) REST enables CRUD to be mapped to database functions (SQL) as follows:
1) Client makes a request to update a resource to the webserver
2) The HTTP request contains all the information required to process the request
3) Javascript allows a pass-through of HTTP requests to the Database server
4) The response is sent back as JSON or XML

Question 33

What are JSON and XML?

Answer 33

1) JSON (Java-Script Notation) and XML are the 2 standard methods for transferring data between the server and the web application
2) JSON > XML

Question 34

What are the advantages of JSON over XML?

Answer 34

1) Easier for a human to read
2) More compact
3) Easier to create
4) Easier for computers to parse and therefore quicker to parse

Question 35

Compare and Contrast thin vs tick client computing?

Answer 35

1) Thickness of Computing refers to the level of processing and storage that it does compare to the server
- Thin = More processing done by server and storage
- Thick = Less reliant on Server higher spec

Question 36

What are the advantages of thin computing?

Answer 36

Advantages:

1) Easy set up as little installation required locally
2) Automatic updates from the server
3) More secure

Question 37

What are the advantages of thick computing?

Answer 37

Advantages:

1) Robust and reliable
2) Can operate without server connection
3) Better for running more demanding software application

Question 38

What are the Disadvantages of thin client computing?

Answer 38

Disadvantages:

1) over-reliant on the server if the server goes down terminal lost functionality
2) Very powerful and expensive server required
3) Increased bandwidth

Question 39

What are the Disadvantages of thick client computing?

Answer 39

Disadvantages:

1) More expensive computers required
2) Individual installation of software
3) Data integrity can be compromised