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.
when is a gateway required
Required when data is travelling from one network to another that use different protocols.
what is a firewall
software or hardware that controls access to and from a network
what is packet filtering
a mechanism in firewalls where packets of data are inspected by the firewall to check which port they are attempting to access.
how does packet filtering work
the header of each packet is examined and compared against a set of rules defined in the firewall.
what is stateful inspection
tracks the state of connections and monitors the entire session
what is stateless inspection
examines each packet independently without context of packets
pros/cons between stateful and stateless
stateful is secure however resource heavy
stateless is fast but limited security
what are proxy servers
servers that make request on behalf of your computer hiding the true request enabling anonymous surfing
what is symmetric encryption
encryption where the same primary key is used to both encrypt and decrypt data and it is sent along with the message
what is asymmetric encryption
a public key is used to encrypt the message but a private key is used to decrypt making it more secure.
what is a digital signature
a private key is used to encrypt the message. the hashed version is sent alongside the original. public key is used to decrypt and the messages are compared to ensure there has been no tampering.
what is a digital certificate
used to trust the identity of the owner of each public key when decrypting the message.
what is a worm
a stand alone program that can be spread without the user running it
what is a trojan
a type of malware which is disguised as legit software and it cannot self replicate.
what is phishing
manipulating users with links to give away personal info
