Flashcards · 9618 · A Level Topic 14

Communication and internet technologies (A Level) flashcards

9 cards on A Level Topic 14, subtopics 14.1 to 14.2. Pick a subtopic or study them all.

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Why are protocols needed in networking?: A protocol is a set of rules for transmitting data. Devices from different manufacturers can communicate only if they follow the same rules.
What are the four layers of the TCP/IP protocol suite?: Application (e.g. HTTP, FTP, SMTP), Transport (TCP), Internet (IP), and Link (e.g. Ethernet).
What is the role of TCP and of IP?: TCP splits data into packets, numbers them, and makes sure all arrive and are reassembled in order (re-requesting lost ones). IP adds addresses and routes each packet across networks.
What are HTTP, FTP, SMTP, POP3 and IMAP used for?: HTTP: transferring web pages. FTP: transferring files. SMTP: sending email. POP3 and IMAP: retrieving email from a server (IMAP keeps it synchronised on the server).
What is BitTorrent?: A peer-to-peer protocol for sharing large files: the file is split into pieces, and each peer (in a swarm) downloads pieces from others while uploading the pieces it has. A tracker helps peers find each other.

What is circuit switching?: A dedicated path is set up between sender and receiver for the whole communication; all data follows that path, in order. Used for traditional telephone calls.
What is packet switching?: Data is split into packets, each with a header holding addresses and a sequence number. Packets may take different routes and are reassembled in order at the destination.
What are the advantages of packet switching over circuit switching?: No line is tied up, so bandwidth is shared efficiently; packets can be re-routed around faults or congestion. Drawback: packets can arrive out of order or be delayed.
What does a router do in packet switching?: It reads each packet’s destination address and uses its routing table to forward the packet to the next router on a suitable route.