Networks - Introduction Flashcards
What is a network?
A collection of connected computers and devices, with the ability to transmit data between each other.
What are the devices in a network known as?
Nodes.
What kinds of devices can nodes be?
- Usually computers
- Printers
- Scanners
- Secondary storage devices
What must each device connect to a network via?
NIC (or equivalent circuitry built into the motherboard)
Why are networks incredibly common now?
Due to the desire to share data and communicate efficiently.
What are the advantages of using a private network?
It gives complete control to the owner, including:
• Security (including data access rights)
• Software provision
• Availability of the service.
What are disadvantages of using a private network?
Requires a team of specialist staff (especially for large networks) to maintain it as well as ensure its security.
What is system redundancy?
Essential equipment is duplicated in the event of a hardware failure.
Why are regular backups made on private networks?
Regular backups ensure a copy of stored data is always available.
What is a Network Interface Card/Controller?
A circuit that uses ethernet connections in order to transmit and receive data.
These are typically built directly into the motherboards of modern day computers.
What is a MAC address?
48-bit identifiers, usually quoted in 6 pairs of hexadecimal numbers.
What does the first three octets in a MAC address do?
What about the rest?
Identify the manufacturer of the equipment.
The rest are allocated in a unique method.
What do Wireless Access Points do? (WAP)
They enable devices to connect to a network temporarily.
From how far away can connections be made?
What concerns does this raise, and what measures are in place?
From approximately 100 metres away.
This causes concern over signal interception.
Methods employed to try circumvent attack include:
- Hiding the SSID
- Encryption
- Limited Access (only accept certain MACs)
What does the SSID do?
What does hiding it result in?
The service set identifier (SSID) identifies a wireless access point.
Hiding it prevents being seen by other users.
How can signals sent between the router and device be encrypted?
Using various standards such as WPA or WPA2/PSK (WiFi protected access), which uses single use cryptographic keys.
In what quantity does the NIC send out signals in?
Packets.
What is a hub?
A hardware device that connects multiple devices in a network. All traffic has to pass through the hub.
How many hubs can you connect together on large networks?
Two or more.
What happens when a hub receives a packet of data?
It re-broadcasts it to every other connected device, ensuring the data gets to where it needs to go.
Why is using a hub on a larger network inefficient?
How is this issue overcome?
Network cables can only carry one signal at a time. As the hub continues sending out redundant data packets, data collisions begin to occur. This affects network performance.
This is overcome by using a switch instead of a hub.
How are hubs and switches similar?
They both physically join network segments together.
How does a switch work?
It has a number of ports and stores the addresses of all network devices that are directly/indirectly connected to it on each port.
As a data packet comes in, its destination address is examined and a direct connection is made between the sending and receiving devices.
What is a bridge?
A hardware device that joins two LANs together using the same protocols.
What about packets do bridges examine?
It examines the destination IP address of each packet.
On a bridge, if the packet is part of the same LAN where it came from, what happens?
It is passed through.
On a bridge, if the packet is not part of the same LAN where it came from, what happens?
It is ‘bridged’ across to that network. It is not re-broadcast on the local LAN where it originated from.
What is a router?
A hardware device that is connected to many networks.
How do routers deal with data packets?
How does it perform this?
It determines the best path through which to send a data packet to the destination node.
It does this by using an internal ‘look up’ table that keeps track of every connection it has available.
Routers receive data packets from one network, and using the _______ provided by the packet, it ________ the packet on towards the correct _______.
Routers receive data packets from one network, and using the ADDRESS provided by the packet, it FORWARDS the packet on towards the correct NETWORK.
How would routers work together?
Each router knows which other routers are closest to it, and by sharing information, it allows the optimum route for a packet to be calculated.
Where are smaller routers used?
In homes to connect computers to the ISP
What kinds of routers do large organisations, and those who run the infrastructure of the internet, use?
Very powerful and high speed routers which direct traffic accordingly.
For who would a centralised location for data storage be ideal for?
For users who all need access to the same data.
What do bridges make the joined networks look like in terms of data packets?
In terms of data packets, it looks like one single, large network.
