1. Network security: Networking Principles Flashcards
How is data sent over networks?
packets
What does it mean for a device to handle packets on a best efforts basis?
Attempts to deliver, but no guarantees
What is a packet?
Finite set of bits comprised of a header and payload
What is a packet header?
Contains routing information, and other details
What is the packet payload?
Actual information being communicated
What is network topology?
A networks connection structure
What are host nodes?
Sources and or destinations of packets in a network
What a communication nodes?
Routers through which packets flow
What does LAN stand for?
Local area network
What does WAN stand for?
Wide area network
What is an autonomous system?
A cluster of routers controlled by a single entity
How are packets routed among nodes in an AS?
(typically) shortest path, to minimise hops and avoid loops
What does AS stand for?
Autonomous system
How are packets router between AS’s?
Determined by contractual agreements (and designed to avoid loops)
What is the physical layer?
Moves bits between nodes (copper, coax, fibre, radio, etc)
What is the link layer?
Deals with the logic to transmit frames to MAC addresses
What layer does the Ethernet protocol operate at?
Link layer
What does MAC stand for?
media access control
How many bits does a MAC address have?
48
What is the network layer?
Moves packets between hosts with an IP address on a best efforts basis
What does IP stand for?
Internet protocol
How many bits in an IPv4 address?
32
How many bits in an IPv6 address?
128
What is the transport layer?
Supports communication between applications based of an IP and port
What layer does TCP operate at?
Transport layer
What layer does UDP operate at?
Transport layer
What does TCP stand for?
Transmission control protocol
What does UDP stand for?
User datagram protocol?
What does TCP do?
Establishes a virtual connection between a client and server. Guarantees delivery of all packets in order.
What does UDP do?
No prior setup, delivers packets ASAP with no delivery guarantees.
What is the application layer?
Provides protocols that support useful functions of the internet.
What layer does HTTP operate at?
Application layer
Does HTTP use TCP or UDP?
TCP
What layer does DNS operate at?
Application layer
Does DNS use TCP or UDP?
UDP
What layer does SMTP operate at?
Application layer
What layer does IMAP operate at?
Application layer
What does SMTP stand for?
Simple Mail Transfer Protocol
What does IMAP stand for?
Internet Message Access Protocol
Does SMTP use TCP or UDP?
TCP
Does IMAP use TCP or UDP?
TCP
What is SMTP used for?
What is IMAP used for?
What does SSL stand for?
Secure Sockets Layer
Does SSL use TCP or UDP?
TCP
What does VoIP stand for?
Voice over Internet Protocol
Does VoIP use TCP or UDP?
UDP
What are the five layers in the TCP/IP model?
- Physical layer
- Link layer
- Network layer
- Transport layer
- Application layer
What is packet encapsulation?
The packet from a higher layer becomes the data in a lower level
What is a network interface?
Interface between two pieces of equipment
What is the structure of a MAC address?
First 3 octets as IEEE-assigned organisationally unique, next 3 must be unique
What does a switch do?
Learns MAC address of each connected computer, forwards frames only for the destination
What layer does a switch operate at?
Link layer
What does a router do?
Maintains table to forward packets to the appropriate network, based solely on destination address
