4.9.4 TCIP/IP Protocol Flashcards by Momin Ahmed

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

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

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What is the function of the application layer?

1) Top of the stack

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

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What is the function of the Transport layer?

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

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What is the function of the Network layer?

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

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What is the function of the link layer?

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

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

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

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

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

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

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

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

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

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

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

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

1) Port 80

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

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

1) Port 443

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

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

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

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How is SSH used for remote management?

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

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

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

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Explain the role of an email server?

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

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

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

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

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

What is an IP address?

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

How is an IP address structured?

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

How many standards of IP address are there?

1) IPv4

2) IPv6

Why was v6 introduced?

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

What is a routable IP address?

1) A Public IP address registered under the DNS

What is Non-routable IP address?

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

What is the purpose and function of DHCP?

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

What is NAT?

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

Why is NAT used?

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

What is Port Forwarding?

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

What is the Client-Server Model?

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

What is the WebSocket protocol

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

What does the CRUD acronym stand for?

CRUD = Create-Retrieve-Update-Delete | Four fundamental operations for any database or content

What is REST?

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

What are JSON and XML?

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

What are the advantages of JSON over XML?

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

Compare and Contrast thin vs tick client computing?

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

What are the advantages of thin computing?

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

What are the advantages of thick computing?

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

What are the Disadvantages of thin client computing?

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

What are the Disadvantages of thick client computing?

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