1.3.3 Flashcards
What is a protocol?
A set of rules to govern communication across a network.
What are some examples of protocols?
TCP
IP
POP
SMTP
IMAP
FTP
What are the benefits of protocols?
Allow networks to communicate by ensuring all devices follow the same rules
This means devices interpret data in the same way
Define and give examples of a standard.
An agreed way of doing things like USB, HTML, MP3
What is the benefit of standards?
Standards make it easier for people to build programs and software that work on different systems in different countries.
What is a DNS, and what is its purpose?
Domain Name System (DNS)
Used to convert a given URL to a corresponding IP address.
What is the process used by a DNS?
URL (www.google.co.uk) is entered and sent to the DNS resolver
DNS servers map this domain to an IP address, by looking up in a lookup table/cache.
If the DNS server cannot find it, it passes the request (recursively) to the top-level domain name server.
If the IP address is found it updates the DNS servers that did not know it.
If it is not found then it will return an error
The original DNS Server sends the IP address to the browser so it can retrieve the website from the server on which it is hosted.
What is an IP address?
Uniquely identifies a device on a network.
An IP address is a logical identifier. (e.g. 192.168.0.1)
State the four layers of the TCP/IP Stack.
Application
Transport
Internet
Link
Describe the application layer and give an example of a protocol used at this layer.
Sits at the top of the stack.
If a browser is used, then it will use HTTP protocols
Describe the transport layer and give an example of a protocol used at this layer.
Uses the Transmission Control Protocol (TCP) to establish an end-to-end connection
Splits the data into packets
Adds the packet number, total, and port.
Describe the internet layer and give an example of a protocol used at this layer.
Routers operate on this layer
Adds the IP address to the packet (to/from)
Describe the link layer of the TCP/IP stack.
Source and destination MAC addresses added.
What are the benefits of protocol layering?
Allows different layers to be worked on independently.
Allows layers to be upgraded without affecting others.
Allows for layers from different providers to be used interchangeably.
What is a LAN?
LAN – Local Area Network
A group of devices connected over a small geographical area.
The equipment is owned by the network owner.
The range could include a building or campus.
What is a WAN?
WAN – Wide Area Network
A group of devices connected over a large geographical area
Often uses third-party communication channels.
Range could include the entire world
Define circuit switching and its associated pros and cons.
Creates a direct link between two devices for the duration of the communication. The public telephone system is an example.
- The connection is set up for the entire duration of the message so
bandwidth is wasted during the periods when no data is being sent. - The two devices must transmit and receive data at the same rate
+ Data packets arrive in the same order that they are sent, simplifying the process of reconstructing the message at the recipient end.
Define packet switching.
Data is split into equal-sized packets.
Each packet has a header of information (including the destination address and the place of the packet in the complete message)
Each packet is placed on the network, each may travel by a different route, meaning they may arrive at different times.
At each node on the network, the destination address is read, and the best route is found.
Packets need to be reordered at the destination.