Network Flashcards 2
Define Network
A computer network is a group of computer systems and other computing hardware devices that are linked together through communication channels to facilitate communication and resource-sharing among a range of users.
What is a Local Area Network (LAN)
A network inside one organization or one building traditionally made of wires and hubs connecting servers and clients. Typically in a business, connecting employee’s PCs to the company’s servers.
What is a Wide Area Network (WAN)
A network that spans many computers in widely separate locations, e.g. separate cities for example, linking bank offices and ATMs. WANS usually include connections that are public, e.g. not owned by the company.
LAN vs WAN Diagram
Example of a WAN Diagram
What is a Virtual Local Area Network (VLAN)
It seems to be a LAN, and is all controlled by one organization. Commonly PART of a LAN, isolated with no connection to other parts of the actual physical LAN. Makes sense for security purposes, isolating sensitive resources.
Example of a VLAN Diagram
What is a Storage Area Network (SAN)?
A network containing large amounts of storage (HDD). Usually
virtualized so users don’t need to worry about the actual machines containing
the storage devices commonly “data centers”
What is a Wireless Local Area Network (WLAN)?
Also called WIFI a WIRELESS LAN, using mostly radio connections to “access point” hubs, with wires connecting the hubs to the servers. Rarely provides direct wireless connections between clients and servers, as cables (wires) are much faster.
LAN vs WLAN Diagram
What is the internet?
• The internet is a globally connected network system that uses the
TCP/IP protocols to transmit data via various types of media.
• The internet is a network of global exchanges – including private,
public, business, academic and government networks – connected
by wired, wireless and fibre-optic technologies.
• The terms internet and World Wide Web are often used
interchangeably, but they are not exactly the same thing; the
internet refers to the global communication system, including
hardware and infrastructure, while the web is one of the services
communicated over the internet.
What is the Extranet?
• An extranet is a controlled private network allowing
customers, partners, vendors, suppliers and other
businesses to gain information, typically about a specific
company or educational institution, and do so without
granting access to the organization’s entire network.
• An extranet is often a private part of a website.
• It is restricted to select users through user IDs, passwords
and other authentication mechanisms on a login page.
Intranet vs Extranet Diagram
What is a Virtual Private Network (VPN)?
Virtual Private Network provides secure, private connections between clients and servers, running across public connections like phone line typically running across the Internet
What is a Personal Area Network (PAN)?
Personal Area Network used to connect devices belonging to one user, or maybe a family. Typically running through wireless router in a home.
PAN Examples
What is a Peer-to-peer (P2P) network
P2P Peer to Peer communicates between “equal” clients, without using servers. Commonly used in the Internet to exchange files directly between client PCs.
Why are internet standards important?
• Without standards, manufacturers of networking products
have no common ground on which to build their systems.
• Interconnecting products from various vendors would be
difficult, if not impossible.
• Without agreed standards, communication would be
difficult (if not impossible)
OSI Model
All People Seem To Need Data Processing
Simplified TCP/IP Model
The 2 fundamental VPN technologies and what they do
• Encryption is the process of encoding data so that only a
computer with the right decoder will be able to read and use
it.
• Tunnelling involves establishing and maintaining a logical
network connection (that may contain intermediate hops).
On this connection, packets constructed in a specific VPN
protocol format are encapsulated within some other base or
carrier protocol, then transmitted between VPN client and
server, and finally de-encapsulated on the receiving side
VPN Tunneling Diagram
Benifits of telecommuting
VPNs Enable telecommuiting here are some of the benifits.
- Increased Productivity
- Improved moral and less stress
- Less environmental impact (transportation etc.)
- Less need for bueiness real estate
What is an internet protocol
Set of rules for data communication over a network
What is data
Anything in a form suitable for use with a computer… such as binary. Typically data is meaningless.
What is a packet
A small unit of data used in network communication
Data packet diagram
Functions of internet protocols
- Ensure data integrity
- Manage flow control
- Prevent deadlock
- Manage congestion
- Perform error checking
What is data integrity?
• Data integrity, in the context of networking, refers to the
overall completeness, accuracy and consistency of data.
• Data integrity must be imposed when sending data through
a network.
What is flow control?
• Flow control is the mechanism that ensures the rate at which
a sender is transmitting is in proportion with the receiver’s receiving capabilities.
• Flow control is utilized especially in cases where the sending
device can send data much faster than the receiver can
digest.
What is deadlock?
• A deadlock is a situation where two nodes or processes are
trying to access the same node at exactly the same moment,
causing neither to be able to proceed.
• It is then up to the relevant protocol to stop both, and requeue them so that they can happen sequentially, letting
traffic flow.
What is conjestion control?
- Congestion refers to a network state where a node or link carries so much data that it may deteriorate network service quality, resulting in queuing delay, frame or data packet loss and the blocking of new connections.
- In modern networks, avoiding congestive collapse involves the application of network congestion avoidance techniques along with congestion control.
What is error checking?
- Error checking or detection refers to the techniques used to detect noise or other impairments introduced into data while it is transmitted from source to destination.
- Error detection often makes use of parity bits, bits at the end of a packet that are calculated to be either a 1 or 0.
Causes for variation in network speeds
- Traffic
- Distance
- Infrastructure
- Envtionmental issues
What is compression?
Data compression involves encoding information to use fewer bits than the original data entity
Reasons for compression
- Backups/archiving
- File transfer
- Media file transfer
- Encryption
Lossless vs Lossy compression diagram
Characteristics of UTP – Unshielded Twisted Pair (metal) transmission
Characteristics of fibre-optic glass transmission
Characteristics of Radio waves (WLAN, WiFi) transmission
What is packet switching
Packet-switching describes the type of network in which relatively small units of data called packets are routed through a network based on the destination address contained within each packet.
Packet switching diagram
Advantages of wireless networks
• Uses unlicensed radio spectrum
– Doesn’t cost anything
• LANs can be set up without cabling
– Doesn’t take space or time to lay the cables. No extra cost on cables
• WiFi can support roaming between access points
– People can switch from router to router automatically depending in
which connection is best
• Global standards (eg. 802.11n)
• Setup costs are minimal
– Many types are available on the market and they are affordable
Disadvantages of wireless networks?
- Interference – as the 2.4GHz spectrum is often crowded with other devices
- Limited Range
- WEP – this encryption is not difficult to hack and WPA2 has solved this problem
- Access Points – these can be used to steal data • Health Concerns
Hardware components of a wireless network
- Node: PC, Laptop, Tablet, Printer
- Wireless network interface card
- Radio waves (Bluetooth/WiFi)
- Connection point: Wireless AP / Router
Software components of a wireless network
- Network Operating System (with drivers)
- Protocol stack (TCP/IP)
- Applications (Browser/File explorer)
Types of wireless networks
- WiFi
- Wimax
- 3G 4G etc.
- Lte
Characteristics of WiFI
• Also called Wireless LAN (WLAN)
• Used in laptops/mobile devices to connect wirelessly to
home network
• Most preferred network type to implement a home network
• Allows relatively slow to fast data transmissions (depending
on the version)
• Backwards compatible with most older Wi-Fi standards
(a/b/g/n)
• Small transmitting radius makes it suited for homes, usually
<20m
Characteristics of WiMAX
• WiMAX = Worldwide Interoperability for Microwave Access
• Designed for large distance high speed internet access
• Relatively cheap method of providing internet over a large area - suited
for poorer countries
• Rivalled by Long Term Evolution (LTE) standard
• Can be used as a form of wireless variant of DSL phone transmission lines
Characteristics of 3G
• The primary way mobile phones access the internet today
• Allows the tunnelling of phone lines (mobiles don’t have to
switch back to phone network when receiving a call
• Relatively fast
Data security CIA
- Confidentiality
- Integrity
• Maintaining accuracy of data - Availability
• DoS attacks
3 Factors of Authentication
- Something you know
- Something you have
- Something you are
What is a firewall
- Hardware or Software (or hybrid of both).
- Controls incoming and outgoing network traffic.
- Analyse data packets based on pre-determined set of rules.
What is a MAC address
• Media Access Control address.
• Hard-coded into devices by manufacturers
• Managed by the IEEE (institute of Electrical and
Electronics Engineers).
• Are used to identify specific pieces of hardware
Types of encryptions
- UserID (and passwords)
- PSK (pre-shared key)
- WEP (dead)
- WPA / WPA2
What is WEP
Wireless Equivalent Privacy Very simple algorithm… … that was very quickly broken!
- Superseded by WPA in 2003
- Deprecated in 2004.
Characteristics of WPA and WPA2
Advanatges of userID
• Advantages: – Access rights to the network can be set for each user – User groups can be created to manage user rights in batches
Disadvantages of userID
• Disadvantages: – A userID can be stolen – system can be bypassed – Does not protect against intercepting messages in the network
Advantages of encryption
– A strong encryption is very hard to break
– Computer are fast enough to encrypt data on-the-fly
Disadvantages of encryption
– Often, users are lazy and take a password that is easy to guess
– The password needs to be transmitted over the network to receiver to allow them to read the message
– Some encryptions are designed to have backdoors built in
