Protocols (Cambridge (CIE) A Level Computer Science): Flashcards
Exam code: 9618
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Define protocol.
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Cards in this collection (48)
Define protocol.
A protocol is a set of rules that define how computers communicate over a network.
What do protocols ensure?
That data is sent, received and understood correctly by all devices, regardless of their manufacturer or operating system.
Name three problems that would occur without protocols.
Devices would not know how to structure or interpret data, data could be lost, corrupted or misrouted, and communication between different hardware and software systems would break down.
Name four things protocols guarantee.
Reliable data transfer, consistent formatting and addressing, error checking and correction, and security during transmission.
Define protocol stack.
A protocol stack is a way of organising network protocols into layers, where each layer is responsible for a specific function.
How do the layers of a protocol stack interact?
Each layer handles its own task independently and communicates with the layers directly above and below it.
True or False?
Each layer of a protocol stack communicates with every other layer.
False.
Each layer communicates only with the layers directly above and below it.
Give two benefits of the stacked model.
It makes the network easier to design, update and troubleshoot, and makes communication modular and efficient.
Protocols allow different technologies to work together using rules.
Protocols allow different technologies to work together using standardised rules.
Give an example of a protocol stack.
TCP/IP
Define TCP/IP.
TCP/IP, the Transmission Control Protocol / Internet Protocol, is a suite of communication protocols used to interconnect network devices on the internet.
Name the four layers of the TCP/IP model.
Application, transport, internet and link.
The TCP/IP layer where the communication process begins is the layer.
The TCP/IP layer where the communication process begins is the application layer.
What does the application layer do?
It interacts directly with software applications, such as web browsers and email clients, and prepares data for transmission over the network.
Define encapsulation in TCP/IP.
Encapsulation is converting data into a format that can be sent and received over the network.
What is the transport layer responsible for?
End-to-end communication between the source and the destination.
What does the transport layer do to the data?
It breaks the data into smaller units called packets, assigns each packet a sequence number, and labels each with a header.
Why is each packet assigned a sequence number?
So the data can be reassembled in the correct order at the destination.
What does the internet layer add to each packet?
A header containing the sender's IP address and the receiver's IP address.
What is the internet layer responsible for?
Routing each packet across the network, using the IP addresses in the headers.
True or False?
The transport layer adds the IP addresses to each packet.
False.
The internet layer adds the IP addresses. The transport layer breaks the data into packets and adds sequence numbers.
What is the link layer also known as?
The network interface layer.
What does the link layer do?
It translates the digital packets into an electrical, optical or wireless signal that can be sent over the physical network.
Name four families of standard protocol.
HTTP and HTTPS, FTP, POP, IMAP and SMTP, and BitTorrent.
Define HTTP.
Hypertext Transfer Protocol allows communication between clients and servers for website viewing.
What two things does HTTP let a client do?
Receive data from the server, such as fetching a webpage, and send data to the server, such as submitting a form or uploading a file.
What is the difference between HTTP and HTTPS?
HTTPS works in the same way but with an added layer of security: all data sent and received is encrypted.
What is HTTPS used to protect?
Sensitive information such as passwords, financial information and personal data.
Define FTP.
File Transfer Protocol allows sending and receiving files between computers.
What is FTP often used for?
Uploading and downloading files to and from a web server.
Give two advantages of FTP.
Greater efficiency, and support for bulk transfers and large files, such as resuming interrupted transfers.
Define FTP client.
An FTP client is a software application that uses the FTP protocol to make the transfer process easier for users.
Which three protocols handle email?
SMTP, POP and IMAP.
Define SMTP.
Simple Mail Transfer Protocol allows communication between an email sender and the email server, and between different email servers using the internet.
Which email protocol sends mail rather than retrieving it?
SMTP
Define POP.
Post Office Protocol downloads emails to a device from an email server. Once retrieved, the email is removed from the server.
Define IMAP.
Internet Message Access Protocol downloads emails to a device from an email server, and a copy is retained on the mail server.
What is the key difference between POP and IMAP?
With POP the email is removed from the server once downloaded. With IMAP a copy is retained on the server.
Give two advantages of POP.
It frees up storage space on email servers, and is faster on slow connections.
Give two disadvantages of POP.
You can only access emails from the device they were downloaded to, and emails are deleted from the server once downloaded.
Give two advantages of IMAP.
You can view and manage emails from any device with internet access, and changes made on one device are synchronised on all connected devices.
True or False?
With IMAP, deleting an email on one device leaves it in place on the others.
False.
Changes made on one device are synchronised on all connected devices.
Give two disadvantages of IMAP.
Server storage space can limit the amount of email retained, and it requires internet access to view emails.
Define BitTorrent.
BitTorrent is a peer-to-peer (P2P) file-sharing protocol used to distribute large amounts of data efficiently across the internet.
How does BitTorrent differ from downloading from a central server?
Users download pieces of the file from multiple peers who already have parts of it, rather than from a single central server.
Give two benefits of BitTorrent.
It is faster, because downloads come from many sources at once, and more efficient, because it reduces the load on any single server.
BitTorrent supports distribution, which avoids the need for central hosting.
BitTorrent supports decentralised distribution, which avoids the need for central hosting.
True or False?
BitTorrent is an illegal technology.
False.
BitTorrent is a legal technology, though it is sometimes used to share copyrighted content illegally, so ethical and legal use matters.
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