1.3 Networks Flashcards
1
Q
Network
A
Two or more linked computers.
2
Q
Advantages of Networks
A
- Users can share files
- Users can share peripherals
- Users can access their files from other computers on the network
- Servers can control security software updates and backup of data.
3
Q
Disadvantages of Networks
A
- Increased security risks to data.
- Malware and viruses spread easily between computers.
- Computer may run slowly if there is a lot of data travelling through the network.
4
Q
LAN
A
Local Area Network
5
Q
WAN
A
Wide Area Network
6
Q
Characteristics of LAN
A
- Covers small geographical area.
- All the hardware for a LAN is owned internally.
- Wired with a UTP/fibre optic cable
- Wireless using Wi-Fi.
7
Q
Characteristics of WAN
A
- Covers large geographical area, linking
LANs together. - Infrastructure between LANs is leased
from the companies who own them. - WANs are connected with telephone lines,
fibre optic cables or satellite links
8
Q
Advantages of LAN
A
- Cheap to set up
- Easy to set up
- Secure
- Rapid communication between devices.
9
Q
Disadvantages of LAN
A
- Limited distance covered.
10
Q
Advantages of WAN
A
- Large distance covered.
- Higher bandwidth.
11
Q
Disadvantages of WAN
A
- Less secure
- Large installation cost
12
Q
Factors affecting Network Performance
A
- Bandwidth
- Contention rate
- Latency
- Error rate
- Transmission media
13
Q
Bandwidth
A
The amount of data that can be sent and received at a given time. Measured in bits per second.
14
Q
Contention rate
A
Too many users on the same network can cause it to slow down as bandwidth is limited.
15
Q
Latency
A
The delay from transmitting to receiving data.
Caused by bottlenecks in infrastructure of network or hardware not operating at the same speed.
16
Q
Error Rate
A
The number of data collisions per second. The higher the error rate, the network slows down as data must be resent.
17
Q
Client-server networks
A
A server controls access and security to one shared file store, manages peripherals and backup of data.
A client makes requests to the server for data and connections.
18
Q
Advantages of Client-server networks
(3)
A
- Easier to manage security files.
- Easier to backup all shared data.
- Easier to install updates on all connected computers.
19
Q
Disadvantages of Client-server networks (4)
A
- Expensive to set up and maintain.
- Needs IT specialists to maintain.
- Single point of failure.
- Users lose access if server fails.
20
Q
Peer-to-Peer Networks
A
All computers on the network are equal and are responsible for their own security and backups.
21
Q
Advantages of Peer-to-Peer networks (4)
A
- Easy to maintain
- No specialists required
- No dependency on single computer
- Cheaper to set up
22
Q
Disadvantages of Peer-to-Peer networks
A
- Less secure
- Difficult to maintain file store
- Users manage own backups
23
Q
Modes of Connection
A
Wired - Ethernet
Wireless - Wi-Fi, Bluetooth
24
Q
Wired Networks
A
Use physical wires to connect devices. Typically used in offices as cables limit their ability to move.
25
Wireless Networks
Use radio waves to carry signals. Range of 50m - walls can interefere.
26
Advantages of Wired Networks
- Speed of up to 1 gigabit per second
- Distance of up to 2km for fibre optic - 100m for Ethernet.
- More secure
27
Disadvantages of Wired Networks
- Installation is expensive
- IT specialists required for set up
28
Advantages of Wireless Networks
- Cheap to set up
- Easy to set up
- Easy to connect
29
Disadvantages of Wireless Networks
- Slower speed - 50 megabits per second.
- Lower range - up to 50m.
- Less secure, data is more easily intercepted.
30
Network hardware
- Network Interface Card (NIC)
- Wireless Access Point (WAP)
- Switch
- Router
- Transmission media
31
Network Interface Card
Allows a device to connect to a network. Uses protocol to determine how connection should work. Every computer connecting to a network needs one.
32
Wireless Access Point
Allows wireless enabled devices to connect to a network without cables.
33
Switch
Sends data between computers and a LAN. Segments networking by forwarding traffic to correct location.
34
Router
Sends data between networks.
Creates a WAN from many LANs.
35
Purpose of Transmission Media
To carry data signals from one computer to another.
36
Types of Transmission Media
- Copper cables
- Fibre optic cables
37
Fibre Optic Cables
Uses light to transmit data.
Covers larger distance and has greater bandwidth than copper cables.
38
Copper Cables
Has a set of wires for transmitting and receiving.
Covers less distance and has less bandwidth, more reliable.
39
Bluetooth
A form of wireless communication that enables different devices to connect.
Limited in transmission speed and range.
40
Star Topology
In a star topology all computers indirectly connect to each other through a switch, which acts as a central point through which all communications are passed.
41
Advantages of Star Topology
- If one computer fails, it does not affect the others.
- Easy to add new devices.
- A message is sent to the intended recipient only.
42
Disadvantages of Star Topology
- Central point of failure - the switch.
- Wired star topology needs lots of cable - expensive.
43
Mesh Topology
Each computer is connected to at least one other computer, which act as relays, passing on signals to its final destination.
44
Partial Mesh Topology
Not all computers are connected directly to each other.
45
Full Mesh Topology
Each computer is directly connected to every other computer.
46
Advantages of Mesh Topology
- Messages can be received quickly.
- Messages should always arrive as there are many routes to take.
- No isolated computers
- Each computer can send and receive from multiple computers at one time.
- New computers can be easily added without interruptions.
47
Disadvantages of Mesh Topology
- Full mesh is impractical because many connections are needed to be set up.
- Lots of maintenance required.
48
IP Addresses
Each device connected to a network has its own unique IP address.
49
IPv4
192.168.0.254
4 sets of up to 3 digit numbers (0-255), separated by dots.
50
IPv6
2001:0000:130F:0000:0000:09C0:876A:130B
8 sets of 4-digit hex values, separated by colons.
51
MAC Addresses
A unique serial number assigned to each NIC which allows a network to uniquely identify any device. Can't change.
A string of hex numbers, separated by colons.
52
Example of MAC Address
1A:5B:6H:98:78:35
53
Protocols
- HTTP
- HTTPS
- POP
- IMAP
- TCP/IP
- FTP
- SMTP
54
TCP/IP
Transmission Control Protocol / Internet Protocol.
Enables communication over the internet.
55
HTTP
HyperText Transfer Protocol
Manages communication between a webserver and a client.
56
HTTPS
HyperText Transfer Protocol Secure
Manages communication between a webserver and a client and secure encryption.
57
FTP
File Transfer Protocol
Governs the transmission of files across a network and the internet.
58
POP
Post Office Protocol
Govern retrieving emails from email servers and deletes the file immediately after being transferred.
59
IMAP
Instant Messaging Access Protocol
Govern retrieving emails from email servers and stores the file on the server after being transferred.
60
SMTP
Simple Mail Transfer Protocol
Governs the sending of email over a network to a mail server.
61
The Cloud
Generic term for remotely accessed storage - accessed through the Internet.
