1.3.3 Networks Flashcards
What is a network?
Multiple computers connected together.
How is a physical bus topology set out? What are its advantages and disadvantages?
All devices are connected to a backbone cable.
Advantages => Cheap, no additional hardware required.
Disadvantages => Central point of failure, data collisions slow the network down, everyone on the network can see the data transmitted.
How is a physical star topology set out? What are its advantages and disadvantages?
All devices are connected to a server/switch.
Advantages => No data collisions means consistent performance, easy to add new devices.
Disadvantages => Central point of failure, expensive.
How is a physical mesh topology set out? What are its advantages and disadvantages?
In a full mesh, every node is connected to every other node.
In a partial mesh, most nodes are connected to most nodes.
Advantages => Performance and reliability increases as more nodes are added, no central server can improve speed.
Disadvantages => Expensive especially on a wired network, difficult to maintain.
What are the network protocols you need to know?
HTTP/HTTPS, POP3, TCP/IP, IMAP, FTP.
What is the HTTP/HTTPS protocol?
Hypertext Transfer Protocol (Secure) is used to render webpages.
What is POP3?
Post Office Protocol 3 retrieves emails from a server but immediately deletes them, meaning inboxes cannot be synced.
What is IMAP?
Internet Message Access Protocol retrieves emails from a server without immediately deleting them, so inboxes can be synced.
What is FTP
File Transfer Protocol transmits files over a network.
What is the TCP/IP stack?
Transmission Control Protocol / Internet Protocol contains 4 layers:
Application, Transport, Internet, Link
What does each layer do on the TCP/IP stack?
Application => Applies the correct protocol required.
Transport => Splits data into packets with a header, payload and trailer, and are given a sequence number and the port used.
Internet => Adds the sender’s and recipient’s IP addresses to the header of the packet.
Link => Adds the sender’s and recipients MAC addresses to the header of the packet.
What is a DNS and why is it used?
A Domain Name System translates domain names into IP addresses, as IP addresses are harder for humans to remember so we use domain names.
What does the header, payload, and trailer of a packet contain?
Header => Sender’s & recipient’s IP address, protocol in use, order of packets, time to live.
Payload => The raw data to be transmitted.
Trailer => The checksum.
What is circuit switching? What are its advantages and disadvantages?
A method of communication where a direct link is created between two devices. The link is maintained for the entire duration of the conversation. It requires both sides to send & receive data at the same speeds.
Advantages => Data is sent in order so doesn’t have to be reconstructed, no delay in the conversation.
Disadvantages => Bandwidth is wasted whilst data isn’t being transmitted, other uses can’t use sections of the network during transmission.
What happens during packet switching? What are its advantages and disadvantages?
- Data is split into packets which have labels, including the address of the sender and receiver, and the sequence order.
- The packets are each sent on the quickest route with the least traffic, meaning they could arrive in the wrong order.
- When all of the packets have reached the recipient, they are reordered.
Advantages => Ensures data arrives intact, multiple routes can be used, packets can be transferred globally.
Disadvantages => It takes time to reconstruct the packets, data can’t be received until all packets have arrived.
