The internet

Question 1

Define ‘the internet’

Answer 1

A network of interconnected computer networks which uses an end-to-end communication protocol.

Question 2

What is an ISP

Answer 2

An ISP is an internet service provider which provides internet access to its customers.

Question 3

what is a ‘packet’

Answer 3

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.

Question 4

What is a packet switched network.

Answer 4

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.

Question 5

How is a packet sent through the internet.

Answer 5

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.

Question 6

What is a packets time to live (TTL)

Answer 6

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.

Question 7

What happens when a packets TTL expires.

Answer 7

When the TTL expires it is said that the packet is dropped, meaning that the packet is deleted.

Question 8

What happens when a packet is dropped.

Answer 8

The recipient will notice that a packet is missing and request that the sender transmits the missing packet again.

Question 9

What is the purpose of the senders address in the packet

Answer 9

Identifies where the packet was sent from, and therefore

Question 10

What is the purpose of the receivers address in the packet

Answer 10

Identifies the packets intended recipient allowing it to be routed to the correct device.

Question 11

Sequence number

Answer 11

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.

Question 12

What is a router and describe its function

Answer 12

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.

Question 13

when is a gateway required

Answer 13

Required when data is travelling from one network to another that use different protocols.

Question 14

what is a firewall

Answer 14

software or hardware that controls access to and from a network

Question 15

what is packet filtering

Answer 15

a mechanism in firewalls where packets of data are inspected by the firewall to check which port they are attempting to access.

Question 16

how does packet filtering work

Answer 16

the header of each packet is examined and compared against a set of rules defined in the firewall.

Question 17

what is stateful inspection

Answer 17

tracks the state of connections and monitors the entire session

Question 18

what is stateless inspection

Answer 18

examines each packet independently without context of packets

Question 19

pros/cons between stateful and stateless

Answer 19

stateful is secure however resource heavy
stateless is fast but limited security

Question 20

what are proxy servers

Answer 20

servers that make request on behalf of your computer hiding the true request enabling anonymous surfing

Question 21

what is symmetric encryption

Answer 21

encryption where the same primary key is used to both encrypt and decrypt data and it is sent along with the message

Question 22

what is asymmetric encryption

Answer 22

a public key is used to encrypt the message but a private key is used to decrypt making it more secure.

Question 23

what is a digital signature

Answer 23

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.

Question 24

what is a digital certificate

Answer 24

used to trust the identity of the owner of each public key when decrypting the message.

Question 25

what is a worm

Answer 25

a stand alone program that can be spread without the user running it

Question 26

what is a trojan

Answer 26

a type of malware which is disguised as legit software and it cannot self replicate.

Question 27

what is phishing

Answer 27

manipulating users with links to give away personal info