3.5 Protocols and Layers

Question 1

Give all the protocols for this topic

Answer 1

• HTTP
• HTTPS
• FTP
• POP
• IMAP
• SMTP
• TCP/IP

Question 2

What is a protocol?

Answer 2

A set of rules that a connection follows on a network

Question 3

HTTP

Answer 3

• Hypertext transfer protocol is used for accessing and receiving web pages via the internet
• Written in HTML
• Protocol requests a web page from the web server and then it receives the web page

Question 4

HTTPS

Answer 4

• Secure HTTP encrypts the information so that it cannot be understood by an eavesdropper
• Sites that include information based on credit or passwords ideally use HTTPS (banks, online shops, social networks)

Question 5

FTP

Answer 5

File Transfer Protocol is used for sending or retrieving files to or from a FTP server

Question 6

SMTP servers

Answer 6

SMTP protocol is when an email is sent to a mail server and forwarded to the internet back to the mail server destination and POP/IMAP to access the email

Question 7

POP and IMAP

Answer 7

Email retrieval protocols fetch message data and attachments from your remote mail server

Question 8

POP

Answer 8

Post-Office Protocol will download every new message to your local device and with them no longer being available on the server - This is similar to the protocol of sending a letter through a post office

Question 9

IMAP

Answer 9

Internet Message Access Protocol will leave the messages on the server/ They can be accessed by multiple devices and they can only be removed if the user deletes them

Question 10

SMTP

Answer 10

• The Simple Main Transfer Protocol is used for sending email (gmail, outlook etc.)
• Needed for when the sender and recipient use different mail services
• Mail server relays the message through various other servers known as mail relays
• Finally the email arrives at the destination mail server

Question 11

TCP

Answer 11

• Transmission Control Protocol breaks up the messages sent over the Internet into small chunks called packets. Reassembles the packets at the other end
• Detects error
• Resends lost messages

Question 12

IP

Answer 12

Internet Protocols routers the individual packets from one IP address to another

Question 13

What is the TCP/IP protocol stack?

Answer 13

Defines 4 layers that enable communication on the Internet. This is a design with each layer being responsible for a small part of the communication process

Question 14

What are the 4 layers of TCP/IP protocol stack?

Answer 14

• Application layer
• Transport layer
• Internet layer
• Link layer

Question 15

Sending data using the stack

Answer 15

The application you are using to send data will determine the correct protocol to use to communicate

Question 16

Application layer (1st)

Answer 16

Computer application produces data for sending. Things like SMTP, FTP and HTTP operate in this layer. HTTP would connect to websites. SMTP would be used for emails and FTP would be used to upload files to a website

Question 17

Transport layer (2nd)

Answer 17

• Transport layer creates the connection between 2 computers or ‘hosts’. Here data is divided up into packets and given a packet number. Packets are reassembled by the recipient’s Transport layer.
• Lost packets are resent
• This layer uses TCP

Question 18

Internet layer (3rd)

Answer 18

Internet layer is responsible for routing packets and routers operate on this layer. Source and destination addresses are written on to the packets ready for transmission

Question 19

Link Layer (4th)

Answer 19

Physical hardware and cables that ‘link’ data. Things like MAC, ethernet and Wi-Fi operate on this layer

Question 20

Receiving data

Answer 20

Data packets move back up the opposite way to how you send it.

Question 21

Advantages of layers

Answer 21

• Layers are self-contained and this means the functionality of one layer can be changed without affecting functionality of other layers
• Different hardware or software operates on a particular layer providing interoperability between providers and systems

Question 22

What are layers?

Answer 22

• A division of network functionality

- A specific function of the network

Question 23

Why do we have protocols?

Answer 23

So we have standards on how computers send and receive messages on a network

Question 24

What are standards?

Answer 24

Specifies the way that computers access a network, speeds on different types of networks, and the types of technologies used