5) Fundamentals of Computer Networks Flashcards
What is a network?
A collection of connected computers
Why might we set up a network?
Data exchange
Managing computers
Resource sharing
What can a network manager manage over other computers in the network?
Updating software
Fixing problems
Help users (password resets)
What resources are commonly shared within a network?
Printers
Scanners
Internet Connections
What is a topology?
How the computers are laid out and connected together
What factors affect the overall performance on a network?
Topology
Bandwidth
Wired vs Wireless
Choice of hardware
What is bandwith?
The amount of data that can be transferred in a given time
Why can increased bandwidth not increase performance?
Bandwidth is shared so there may be too many users
What is transmission media?
Different ways of physcially transferring data along a network
What are fibre-optic cables made out of?
Thin strands of glass which transmit binary data as pulses of light
What are advantages of fibre-optic cables?
Do not suffer interference
Very high bandwidth (100Tbps)
What is fibre-optic cabling appropriate or?
Long distance communcation such as undersea channeling
What are the types of transmission media?
Fibre-optic cables
Radio waves
Coaxial cable
Twister-pair copper cable
What are radio waves?
The transmission media of wireless networking
What is a coaxial cable?
A wired transmission media where and insulated copper wire is surounded by a metal mesh to protect it from interference
What are coaxial cables most often used for?
Cable television
What is the twister-pair copper cable often referred to as?
An Ethernet cable
What is inside a twister-pair copper cable?
8 wires twisted in pairs which reduces interfernce
What do twisted cables ratings indictae?
How quickly data can be transferred
What can Cat-5e transmit at?
1 Gbps
What can Cat-6 transmit at?
10 Gbps
What are the geographical classifications of networks?
Personal area network
Local area network
Wide area network
What does PAN stand for?
Personal area network
What does LAN stand for?
Local area network
What does WAN stand for?
Wide area network
What is a PAN used for?
Connecting a single user’s devices
What is a WAN used for?
Connecting international offices for multionational companies
What is a WAN?
A collection of computers connected over a large geographical area
What is a LAN?
A collection of computers connected over a small geographical area?
What are examples for each geographical calssification of network?
PAN- Bluettoh headset to phone
LAN- Homes, Schools
WAN- The Internet
What is WiFi?
A set of protocls that define how network devices can communicate wirelessly over radio waves
What are WiFi standards?
- g - 54Mb/s
- 11n - 600Mb/s
- 11ac - 3.2Gb/s
How can we ensure devices are comaptible?
By creating devices which uses the same WiFi standards
How do we try to avoid interference?
By splitting frequencies into bands and channels
What frequency bands fo most WiFi standards transit data using?
2.4 Ghz
5 Ghz
How many channels are in the 2.4 Ghz frequency band?
13
3 of these do not intefere with each other
How many channels are in the 5 Ghz frequency band?
24 non-overlapping channels
What are WiFi security methods?
Wired Equivalent Privacy (WEP)
WPA
WPA2
What does WEP stand for?
Wired Equivalent Privacy
What does WPA stand for?
WiFi protected access
What is WEP?
Nedding a password to join a network
No data is encrypted so can be easily intercepted
What is WPA?
Uuses a password to join a network
Uses encryption to scarmble data being sent
What is WPA2?
Successor of WPA
Stronger encryption algorithm
Rank the WiFi secuirty measures from strongest to weakest
WPA2
WPA
WEP
What is the star toplogy?
Each device is connected to a central switch or server
Where are star topologies common?
LANs
What are features of star topologies?
Simultaneous access
Reliable
Scalable
Expensive
Why is a star topology reliable?
If a single client fails all the other clients can continue
If the server fails the whole network is affected
What is the bus topology?
Each computer is connected to a main cable called the bus
What are features of bus topologies?
Little cabling
Unreliable
Easily expanadable
Difficulty troubleshooting
Why can problems within a bus topology network be hard to find?
A break in the main cable could have occured in any place
Why is a bus topology unreliable?
If the main cable is broken the network is shut down
What does IP stand for?
Internet Protocol
What are IP addresses used by routers to determine?
Whether a packet’s destination is within the network or not
What happens if a packet’s detinsation isn’t within the current network?
The router will pass the packet onto the WAN
Other routers can use IP address to figure out where to send the packet
What are IP addresses used for?
Identifying where data packets are from and where they need to go
Where must IP addresses be unique?
Within the same LAN
Why are there different types of IP address?
IP addresses are not universally unique
What are the types of IP address?
Static IP vs Dynamic IP
Private IP vs Public IP
IPv4 vs IPv6
What is a static IP address?
A device that has the same IP every time it connects to the network
What is a dynamic IP address?
A device that will be allocated a new IP address every time it connects to the network
What provides dynamic IPs?
Dynamic Host COnfiguration Protocl
(DHCP) server
Describe a private IP
Devices within a LAN can have a private IP
These can be used to exchange data between devices on the LAN
Describe a public IP
Routers which connect a LAN to a WAN have a public IP
These are used when other networks on the WAN want to send data to the LAN of the router
What is the IPv4 format?
32-bit numbers
11.22.33.44
What is the IPv6 format?
128-bit numbers often 8 groups of 4 hex digits
111A.222B.333C.0000.0000.0000.0000.888D
What does NIC stand for?
Network Interface Controller
What does every NIC have?
A globally unique MAC address
What does MAC stand for?
Media Access Control
When are MAC addresses assigned?
When the device is manufactured and cannot be changed
How many MAC address do devices with multiple interfaces have?
Multiple MAC addresses
What are uses of MAC addressing?
Used to exchange data on the same LAN
Used by swithces and NICs to send data to the intended recipient
What is the MAC address format?
48-bit numbers as pairs of hex digits
1A.2B.3C.4D
What does each half of a MAC address mean?
First half = manufacturer
Second half = Individual device produced
What are netowkr protocols?
A set of rules that define how data is transmitted beween connected devices
What are the transmission protocols?
IP Ethernet WIFI Transmission Control Protocol (TCP) User Datagram Protocol (UDP)
What does the IP define?
How packets should be sent between networks
IP header added to packets with source and destination
What does ethernet define?
How data should be physically transmitted
What does WiFi define?
How data should be transmitted using radio waves
What does TCP stand for?
Transmission Control Protocol
What does the TCP do?
Splits data into packets
Each packet has a header and payload
What is the payload of a data packet?
The actual data
What does UDP stand for?
User Datagram Protocol
What does the UDP do?
Performs same functions as TCP but doesn’t check packet has arrived
What are the differences between TCP and UDP?
UDP faster but less reliable than TCP
UDP better for gaming
What are the web protocols?
HTTP
HTTPS
File Transfer Protocol (FTP)
What does HTTPS stand for?
Hypertext Transfer Protocol Secure
What is HTTP mainly used for?
Accessing websites from servewrs
What does HTTP define?
How data should be exchanged between web browsers and web servers
What does HTTPS use to encrypt data between the client and server?
Secure Socket Layer (SSL)
What does SSL stand for?
Secure Socket Layer
What does FTP define?
How binary and text data can be requested from a server and transmitted back to the client
What is FTP used to do?
Download or transfer files over a network
What does FTP stand for?
File Transfer Protocol
What are the email protocols?
SMTP
IMAP
POP
What does POP stand for?
Post Office Protocol
What does POP do?
Defines how emails can be retrieved from a mail server
Once user has dowloaded mail from server, server deletes copy and only local copy remains
What does IMAP stand for?
Internet Message Access Protocol
Why is IMAP more popular than POP?
Ability to sync multiple devices
Inboxes remain constant across multiple devices
What does SMTP stand for?
Simple Mail Transfer Protocol
What are almost all e-mails sent using?
SMTP
What does SMTP define?
How emails are sent from an e-mail client to a mail server
What is a protocol layer in a protocol layer model?
A group or collection of network protocols that work at a similar level within the networking process
What are properties of netwrok layers?
Layers of protocol layer model should be inedpendent
Layers should only interact with each other by considering inputs and outputs of that layer
What are layers an example of?
Abstration
What are the 4 layers of the TCP model?
Application
Transport
Internet
Network Access
What does the application layer do?
Creates and interprets data (HTTP, IMAP, FTP)
What does the transport layer do?
Splits/joins data (TCP)
What does the internet layer do?
Adds addresses to data (IP)
What does the network access layer do?
Converts data into electrical signal, hardware (Ethernet, WiFi)
What are the 7 layers of the OSI model?
Application Presentation Session Transport Network Data Link Physical
What are the first three layers of the OSI model grouped into in the TCP model?
The application layer
What layer is the same in both the TCP and OSI model?
The transport layer
What is the OSI’s network layer called in the TCP model?
Internet
What are the bottom two layers of the OSI model grouped into in the TCP model?
The network access layer
What are advantages of layering?
Application developers create apps without network knowledge
Specialists can work on one layer
Layers can be changed without affecting others
Individual layers can be debugged
What are the 2 common layering models?
TCP
OSI
What does TCP stand for?
Transmission Control Protocol
What does OSI stand for?
Open Systems Interconnection
What are the first 3 sections of a URL?
Protocol
Path
Domain
