The Internet Flashcards
What is the difference between an intranet and an extranet?
An intranet is used for communication within an organisation, high security
An extranet allows some connections outside of the organisation, but is not available to the public
What is a Network Address Translation table?
A table used to match the private IP addressed on a network with public IP addresses
How do you determine if two computers are on the same subnet?
AND subnet mask with computer A’s IP
AND subnet mask with computer B’s IP
compare results (network IDs)
If they are the same, they are on the same subnet
What the Dynamic Host Configuration Protocol (+ purpose)?
A protocol for assigning dynamic IP addresses to devices on a network, so that unused IP’s can be put back into the IP pool to allow more devices to connect to the network
What is a Regional Internet Registry, IANA and NRO?
An organisation that controls and assigns Internet addresses in a region which they are provided by The Internet Assigned Numbers Authority (IANA). The 5 RIRs combined to form the Number Resource Organization
What is the difference between a router and a gateway?
A router connects two or more computer networks
A gateway connects two or more computer networks using different protocols
How does a gateway deal with packets using different protocols?
Strips the header of each packets and replaces it with a new one
How does packet switching work?
Split a message into packets, each with a destination address and a sequence number. Dispatch the packets though the internet with a router, with each subsequent router forwarding them. Reassemble packets when they reach their destination.
Explain the two techniques used by a firewall to examine incoming data
Packet Filtering -
Examine the headers of packets, including port, destination etc.
Stateful Inspection -
Examine the actual data of packets to check for malicious code
Explain the steps in sending and receiving a message using asymmetric encryption + how a digital signature is created and verified
Sender -
Digest calculated with hash algorithm
Encrypt digest with senders private key, this is the digital signature
Append digital signature to message
Encrypt with receiver’s public key
Receiver -
Decrypt message with receiver’s private key
Decrypt digital signature with sender’s public key
Rehash message to get digest
If the calculated digest and the received digest are the same, the message is authentic
What is the difference between a virus and a worm?
A virus needs human action to spread, a worm does not
What is the difference between a trojan and a worm?
A trojan does not self replicate
What does the application layer of the TCP/IP stack do (+ protocol example)?
Selects the appropriate protocol for communication and interact with the user (HTTP, FTP, POP3, IMAP, SMTP)
What does the transport layer of the TCP/IP stack do (+ protocol example)?
Establishes end to end communication, error control, packet switching, choosing port number (TCP, UDP)
What does the network layer of the TCP/IP stack do (+ protocol example)?
Supplies IP addresses for source and destination, packet routing (IP)
