HTTP, Used to make a request for a webpage. The server returns the page or an error code if there was a problem with the request., HTTPS, Sends an encrypted request for a webpage. The server returns the encrypted page or an error code if there was a problem with the request., FTP, Used to upload or download a file. The server opens a data connection (over which the file will be transferred) or sends an error code if there was a problem with the request., SMTP, Used to send an email to an email server. The server returns a code indicating whether or not the email could be delivered., POP, Used to request any new emails for a specific email account. The server returns the emails (if there are any)., IMAP, Used to synchronise a client email account with an account on a mail server. The server returns new emails (if there are any) and deletes any emails that were deleted locally on the client application. This allows a user to use multiple devices to access their email account., DHCP, Used to assign IP addresses and other configuration options to devices in a network., TCP, When data is to be sent (whether from client or server), the data is split into packets and each packet is given a sequence number. This is a reliable transmission protocol. At the receiving end, the packets are checked. If any packets go missing, they will be resent., UDP, Data is split into packets (as with TCP). However, this is an unreliable transmission protocol. If any packets arrive out of sequence or are missing, they are ignored. UDP is suitable where data does not have to be 100% accurate but speed is important, e.g. with some video streaming services or VOIP., IP, Creates a new packet (imagine putting the packet from the transport layer into a new envelope). Adds the source and destination IP addresses to allow the packet to be delivered. These are the packets that are routed across the internet., Ethernet & WiFi, Encapsulates the data from the previous layer into frames (another kind of packet) with a source and destination MAC address, and manages multiple transmissions on the media..

Network Protocols (A Level)

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