Week 1 - Net Flashcards
What is the internet?
A global interconnection of different data networks
What are communication systems used for?
They allow applications to transfer data and information, which typically run as distributed systems
What is a DSL modem?
A local connection to WAN. It connects you to your ISP only.
Creates a signal compatible with the WAN network technology.
What does an internet router do?
Knows how to communicate with your ISP.
Interconnects two or more different networks.
Provides global connectivity, allows communication between networks.
What does Ethernet switch do?
Provides wired connections for local devices.
Allows devices within a network to communicate.
What does a bridge do?
Provides connections for local devices, hiding low-level physical connectivity. Connects two different physical interfaces for the same
technology, or interconnects to segments of a LAN.
Example of WAN?
global networks, point-to-point links
Example of LAN?
home, office, building
What does an ISP do?
provider of global internet connectivity and sometimes also WAN connectivity for customer
How do all technologies/OS/ application platforms talk to each other?
common architecture (logical), different engineering (implementation)
What is the internet a collection of?
different services and applications
different networks
different technologies
different service providers
What are the 5 layers of the Internet protocol reference model?
application layer transport layer network layer link layer physical layer
What is protocol?
a set of conventions governing the treatment and especially the formatting of data
in an electronic communications system network protocols
Two parts of an unconfirmed service?
request sent
indication recieved
Two parts of a confirmed service?
response from reciever
confirm at sender
Explain connection-less
- send and recieve data
- send and forget
- service is typically unconfirmed
- suitable for bursty data
explain connection orientated?
- connection establishment
- data transfer
- connection release
Advantages of CL?
- low latency
- low traffic overhead
advantages of CO?
- reliable delivery
- ordered delivery
- no duplicates
- control of packet flow
Disadvantages of CL?
- no reliability
- no ordering
- possible duplication
- no control of packet flow
disadvantages of CO?
- connection overhead
- latency
- taffic overhead
- no flow rate control
What is the message format for encapsulation?
header (maybe trailer) + payload/body
What allows the protocol to operate?
The header
what is XPDU
X protocol data unit
in layered architecture, each layer has..?
- a specific purpose
- provides a service to the layer above
- has a function that depends on one or more protocols
What is a server?
a host / program that provides a service
- waits for clients to connect to make use of service
what is a client?
a program that makes use of a service.
- must identify a server and connect to it
what does FQDN stand for
fully qualified domain name
what is an IPv4 address?
a 32 bit unsigned number, normally written in dotted decimal notation
What does DNS stand for
domain name system
what does dns do
maps fqdn to address
What does a simple application packet consist of?
data
TCP header
IP header
