Protocols

Question 1

Protocols

Answer 1

standards/rules used to define how devices communicate. They govern the transmission of data.

Question 2

Each protocol has its own method to determine:

Answer 2

• How data is formatted when sent
• How the data is compressed
• The size of message and speed of transmission
• How to check for errors in data

Question 3

Handshaking

Answer 3

the client requests access, the server grants it and the protocols are agreed

Question 4

Packets

Answer 4

collections of data forming part of a message

Question 5

Packet switching

Answer 5

• packets are sent individually across a network
• packets from the same message may take different routes according to the availability and traffic conditions
• the packets are assembled to form the complete message at the receiving end.

As well, it improves the reliability of sending messages because if one route is busy, another can be found.

Question 6

TCP/IP model

Answer 6

• Consists of four layers, with each layer responsible for a small part of the communication process. Referred to as a modular design.
• Advantage - is that each layer of the protocol software can be easily adapted for specific hardware and operating systems

Question 7

Application layer

Answer 7

Encodes the data being sent so that it will be understood by the recipient.

This means formatting data and adding an appropriate header according to a protocol being used, such as HTTP or FTP.

Question 8

Transport layer

Answer 8

Splits the data into packets and adds packet information such as, packet number specifying that packet’s order and the total number of packets so they can be reassembled correctly.

Question 9

Internet layer

Answer 9

Attaches the IP address of the sender so the recipient will know who sent it. It also attaches the address of the host that is sending the data and the destination IP address.

Question 10

Link layer

Answer 10

Attaches the Media Access Control (MAC) addresses of the sender and the recipient, allowing the packet to be directed to a specific device on a local area network.

At the receiving end, these data packets are passed back up the protocol stack.

Question 11

Protocols – application layer:

Answer 11

HTTP
FTP/SFTP
SMTP
POP3
SNMP

Question 12

Hyper Text Transfer Protocol - HTTP

Answer 12

• used to access and receive web pages in the form of HTML files
• protocol requests the web server to transmit the requested web page to the user’s browser for viewing
• HTTPS encrypts

Question 13

File Transfer Protocol - FTP/SFTP

Answer 13

• Used to transfer files online
• For moving information from the computer you’re working on to the server where the website is hosted
• Can be used to share/upload files. File is uploaded onto the FTP server and link sent to another person

Question 14

Simple Mail Transfer Protocol – SMTP

Answer 14

• Used for sending email messages
• Needed when using different email service providers
• At least one requirement of this protocol is the specification of an IP port address on which this protocol will ‘listen’ for the messages
• Requires a sender name, receiver name, subject and body

Question 15

Post Office Protocol - POP3

Answer 15

• Used for receiving emails
• POP receives and holds email on the server until the user picks it up
• User can download all emails from the server to store on their computer
• Creates local copies of emails and deletes the originals from the server, so emails are on the user’s devices

Question 16

Simple Network Management Protocol – SNMP

Answer 16

• Used for network management
• Used for collection information from and configuring network devices such as, servers, printers, hubs, switches and routers on an Internet Protocol (IP) network

Question 17

Protocols – transport layer:

Answer 17

TCP

UDP

Question 18

Transmission Control Protocol – TCP

Answer 18

• Standard which defines how messages are broken up into packets and reassembled at the destination. It detects errors and re-sends lost packets.
• Different to IP as it identifies the location on the internet
• When you load a web page, computer sends TCP packets to the web server, asking it to send the webpage to user.

Question 19

TCP Process

Answer 19

• Web server responds by sending TCP packets, which your web browser puts together to form the web page and display it.
• Each time you do something, the web browser sends TCP packets to the server and the server sends TCP packets back
• 2 way communication – systems sends packets back to acknowledge it has received from your packets

Question 20

How does TCP ensure packets reach their destination?

Answer 20

by numbering them, messages are sent confirming the delivery, if these confirmation messages don’t reach the sender, the packets are resent to ensure delivery

Question 21

How is TCP reliable?

Answer 21

because packets are checked for errors, packets are tracked so data is not lost or corrupted in transit

Question 22

User Datagram Protocol – UDP

Answer 22

• Datagram is the same thing as a packet of information
• Similar to TCP – but without checking for errors. This makes it faster because the messages confirming delivery slows communication down.
• Packets are sent, the sender won’t wait to check if the packet has been received, will continue sending packets

Question 23

What happens if UDP packets aren’t received?

Answer 23

the recipient can’t request the missing packets, no guarantee that all packets have been received. Means that computers communicate at a faster speed.

Question 24

When is UDP best used?

Answer 24

when communication needs to take place quickly

Question 25

Protocols – network layer:

Answer 25

IP | ICMP

Question 26

Internet Protocol – IP

Answer 26

* Identifies the location of a device on the internet * Allows data packets to reach the appropriate destination on a network * The IP address is a number which is linked to all online activity from a computer on a network

Question 27

Why is IP needed?

Answer 27

- Your computer connects to the internet indirectly. - First, you connect to a network that is A) connected to the internet itself and B) grants access to the internet. - IP is responsible for addressing, delivering and routing your online requests precisely.

Question 28

IP address

Answer 28

We are used to domain names, these are changed to a numerical IP address by a Domain Name System (DNS) server.

Question 29

Internet Control Message Protocol – ICMP

Answer 29

- error-respnding protocol | - used to create and send error messages to the source IP addresses when network problems prevent delivery of IP packets

Question 30

Reasons for protocols

Answer 30

- Managing the network - Dealing with how different data types should be structured - Ensuring the appropriate transfer of information between devices attached to the internet,

Question 31

Benefits of using layers when working with network protocols

Answer 31

- set rules for each layer - layers are self contained - each layer of protocol software can be easily adapted for specific hardware and operating systems

Question 32

TCP/IP Protocol stack model

Answer 32

Host (your laptop) Application layer (HTTP) > transport layer (TCP) > network layer (IP) > data link layer >>>> > data link layer > network layer (IP) > transport layer (TCP) > application layer (HTTP) > Target (webserver)