The internet Flashcards
Define ‘the internet’
A network of interconnected computer networks which uses an end-to-end communication protocol.
What is an ISP
An ISP is an internet service provider which provides internet access to its customers.
what is a ‘packet’
A container in which data is transmitted over networks. like an envelope in postal system, labeled with address for their sender and recipient and contain information intended for the recipient.
What is a packet switched network.
A network in which data is sent in packets. 1 message is frequently split into multiple packets, each of which is sent to its recipient via the best possible route before being reassembled with other packets by its recipient.
How is a packet sent through the internet.
It passes through a number of routers before reaching its destination. A router uses the recipient address on a packet to determine where to send the packet. Every time that a packet passes through a router, a hop is said to occur.
What is a packets time to live (TTL)
Each packet can only pass through a finite number of hops. A packets TTL indicates how many hops the packet can partake in and is reduced by one with each hop.
What happens when a packets TTL expires.
When the TTL expires it is said that the packet is dropped, meaning that the packet is deleted.
What happens when a packet is dropped.
The recipient will notice that a packet is missing and request that the sender transmits the missing packet again.
What is the purpose of the senders address in the packet
Identifies where the packet was sent from, and therefore
What is the purpose of the receivers address in the packet
Identifies the packets intended recipient allowing it to be routed to the correct device.
Sequence number
Contains the number of packets in a message and identifies a packet’s position in relation to others. This allows packets to be reassembled in the correct order and allows missing
packets to be identified.
What is a router and describe its function
A router is a device that connects 2 or more packet-switched networks or subnetworks. Routers send packets to their recipient via the fastest possible route.
