5. Structure of the Internet Flashcards
Define World Wide Web
A system of interlinked Hypertext Documents accessed vie the Internet
Define Gateway
Connects networks that use different Link Layer Protocols
Define Router
A device that interconnects with 2 or more computer networks which interchange packets
Define Intranet
A private computer network that uses Internet protocols to securely share information
Explain Packet Switching
- Data is split into packets. This has from/to address and payload. Order of Packets noted for larger bits of data
- Packets are sent onto the network, moving from router to router allowing different packets to take different routes
- Once Packets arrived, they are reordered. Confirmation sent back
- If host doesn’t get confirmation, packets are resent
Advantages of packet switching
Data can easily be resent if it arrives incorrectly
Data can be re-routed around any problems
Allows the Internet to grow easliy
Simplifies the routers and the Internet
Define IP address
Unique numerical label assigned to every computer or electronic device on a network
Define IPv4
Current IP standard. Uses 32 bits so there are 2^32 possible addresses (around 4 million)
Define IPv6
New IP standard. Uses 128 Bits so 2^128 possible addresses
Explain the 2 parts of the IP address
Example: 192.168.0.32
- 168 : Network ID
- 32 : Host ID
Define Domain Name
A name that identifies 1 or more IP addresses
Define FQDN
Fully Qualified Domain Name
Must have Host ID and Domain Name
Define DNS Server
A server that translates FQDN into IP addresses
What is the first level of Domain Names
Root level. Contains international and generic labels
Com, UK, org, net etc…
Define URL
Uniform Resource Locator
A character string referring to the location of an Internet resource
Define URI
Uniform Resource Identifier.
Specifies how to access a resource in the Internet
Define the parts of this FQDN:
http://commons.wikimedia.org/wiki/picture.jpg
http://commons.wikimedia.org/wiki/picture.jpg
Http:// : Protocol commons : Host wikimedia : Domain Name .org : Top Level Domain /picture.jpg : location on server
Define Server
A software process that provides a service requested by a client
Examples of Server Software
Printing , File Sharing, Accessing Webpages
Define Client
Software process that accesses a service made available by the server
Explain the Client Server Model
- Client sends a request to the server (Example: for a Webpage)
- The server fetches the page (from Secondary Storage)
- The server sends the data back to the Client
Define Protocol
A set of agreed Signals, Codes and Rules that allow data communication between devices.
Define Port
An address for a software process
Define Socket
A combination of Host IP address and port number
Define Protocol Stack
A collection of Protocol layers.
Each Layer is responsible for part of the process governed by the stack
Define Packet Sniffing
Using Router to read the contents of packets being sent
Define FTP
File Transfer Protocol
Application layer protocol that sends data. Can be private and anonymous.
Uses Port 20 for Data and Port 21 for Commands
Define HTTP
Hyper Text Transfer Protocol
Allows for transmission of Hypertext Documents.
Uses Ports 80 and 8080
Define Telnet
Text based Protocol between server and remote client
Uses Port 23
Define SMTP
Simple Mail Transfer Protocol.
Used for sending email
Port 25
Define POP3
Post Office Protocol 3
Used for receiving Email
Port 110
Define HTTPS
Hypertext Transfer Protocol Secure.
Uses Secure Sockets Label
Port 443
Define MAC Adress
Unique identifier assigned for Network Connections.
Embedded into every Network Interface Card during production
What are the 4 Layers of the TCP/IP Stack
- Application Layer
- Transport Layer
- Network / Internet Layer
- Link Layer
Explain Layer 1 of the TCP/ IP Stack
Application Layer.
Handles the Data being sent. Uses the correct protocol for whatever is being sent.
Uses HTTP, FTP etc…
Explain Layer 2 of the TCP/ IP Stack
Transport Layer.
Splits the data into packets to be sent. Adds the number order. Adds the Port Number (protocol)
Explain Layer 2 of the TCP/ IP Stack
Network / Internet Layer
Adds the To and From IP addresses. Combined with the Port a number, this creates the Socket
Explain Layer 4 of the TCP/ IP Stack
Link Layer.
Handles the Physical details. Adds the MAC Addresses of the sender and recipient. This specifies the hardware devices to use
Define Bidirectional
Data passes both ways at the same time
Define Client Port Numbers
Temporary Port Numbers used by client processes.
They lie in the range 1024 - 4095
Define Well Known Port Numbers
Universally known port numbers used by servers.
They lie in the range 0 to 1023
Explain the HTTP Get process
- Accepts a URI from the user, gets the FQDN and uses DNS server to get the correct IP address
- Sends a GET request to the IP address on Port 80 unless another is specified
- File is sent back, where is is displayed in the users web browser.
- If the file contains other URIs, such as a reference to a graphic, anther GET request is sent for that.
Define Internet
A global system of computer networks that use the standard Internet Protocol suite TCP/IP
