topic 5 computer networks Flashcards
describe the function of the application layer SPEC
this is where the network applications, such as web browsers or email programs, operate.
what happens in the application layer
determines what protocol to use
describe the function of the transport layer SPEC
this layer sets up the communication between the two hosts and they agree settings such as the size of packets
what happens in the transport layer
creates a connection between 2 devices
describe the function of the internet layer SPEC
addresses and packages data for transmission. Routes the packets across the network.
what happens in the internet layer?
writes the destination onto the data packets for transmission
describe the function of the link layer SPEC
this is where the network hardware such as the NIC (network interface card) is located.
what happens in the link layer?
physical hardware that connects 2 devices
describe the role of HTTP
Provides a way for users to interact with web resources.
Transmits messages between client and server using hypertext.
describe the role of HTTPS
As HTTP but in addition uses an encryption protocol to ensure communications are secure.
describe the role of IMAP
Stores email messages on an ISPs server but allows user to manipulate messages as though on a local device. Local devices access the ISP server to access the messages. IMAP works with desktop clients and webmail clients. Allows simultaneous logins from different devices to one account
describe the role of SMTP
Enables users to send (and receive) email messages.
Initiates sessions between user and mail server. Server then forwards messages. Uses a process called ‘store and forward’ to store messages and forward as necessary. The server decides which server to send the message to and the inbox provider then downloads the message and places it in the recipient’s inbox.
Often used in conjunction with IMAP.
describe the role of FTP
Allows secure transfer of files between client and server. Files are uploaded to and downloaded from the server using FTP.
describe the role of TCP
Connects network devices to the Internet. It defines how applications can create channels of communication across a network. It manages how a message is assembled into smaller packets before transmission and reassembles packets in the correct order at destination.
describe the role of UDP
Communications protocol that establishes low latency and loss-tolerating connections between applications. Enables the transfer of data before an agreement is provided by the receiving party. This speeds up transfers.
Can start transferring data before agreement is received from receiving party.
describe the role of IP
Relays data across network boundaries. It defines how to address and route each packet to make sure it reaches the right destination.
