Networks and Communications Flashcards
What is the role of a Router?
A router connects two or more
networks together. Regulates the flow of packets from one network to another.
What is the role of a Switch?
A switch connects devices into a network. Directs and routes packets within a network efficiently.
What is the role of a Firewall?
A software or hardware device that blocks or allows packets based upon a predefined set of rules.
What is the role of a Modem?
Modulator/Demodulator. Changes digital signals to analogue and back so that they are suitable for transmission.
What is the role of a Network Interface Card (NIC)?
A NIC acts as a gateway by translating ethernet packets into usable data for the computer.
What is the role of a Wireless Access Point (WAP)?
Allows wireless devices to connect to a wired network.
What is the role of a Bridge?
Network bridges are devices that allow multiple LANs to communicate with one another. Works on MAC Addresses.
What is the role of a Gateway?
Connects two networks with different transmission protocols.
What is the role of a Repeater?
Regenerates the signal before the signal becomes too weak or corrupted, to extend the range.
What are the characteristics of Broadcast Radio? Pros/Cons?
Broadcast radio is a wireless transmission medium that distributes radio signals through the air.
* Long Distances
* Susceptible to Noise
What are the characteristics of Satellite Transmission? Pros/Cons?
Recieve microwave signals from earth-based station and broadcasts it back over a wide area.
* Very Long Distances
* Limited Bandwidths
What are the characteristics of Microwave Transmission? Pros/Cons?
Involves sending signals from one microwave station to another.
* Highspeed/High Bandwidth
* Line of Sight Required
What are the characteristics of Celluar? Pros/Cons?
Cellular radio is a form of broadcast radio that is in wide use for mobile communications.
*Can support many concurrent users
*Infrastructure Required
What are the characteristics of Unshielded Twisted Pair (UTP)? Pros/Cons?
Twisted‐pair cable consists of one or more twisted‐pair wires bundled together.
*Cheap/Easy to Install
*Low Range/Prone to Interference
What are the characteristics of Shielded Twisted Pair (STP)? Pros/Cons?
Two copper wires that are twisted together are coated with an insulating coating.
* Prevents Interference/Larger Range
* More Expensive/Thicker
What are the characteristics of Fibre Optic? Pros/Cons?
The core of a fibre optic cable consists of dozens or hundreds of thin strands of glass of plastic that use light to transmit signals.
* Large Carrying Capacity/Immune to EM Interference
* Expensive
Describe the types of Fibre Optic.
Single Mode - Light travels over one path and does not disperse. Is good for long distances.
Multi-Mode - Generate light pulses which travel at different angles. Better for short distance but modal distortion can occur.
What are the layers of the TCP/IP Model?
- Application Layer
- Transport Layer
- Internet Layer
- Network Layer
What is the Application Layer of the TCP/IP Model?
End-User applications and service interact with the network using protocols such as HTTP, SMTP and FTP.
What is the Transport Layer of the TCP/IP Model?
Responsible for end-to-end communication between devices ensuring error-free delivery, using TCP and UDP protocols.
What is the Internet Layer of the TCP/IP Model?
The internet layer handles the addressing and routing packets among multiple networks. Uses IPv4 and IPv6.
What is the Network Layer of the TCP/IP Model?
Involves the transmission of data over a physical medium such as UTP or STP.
List three types of Wireless Communications Protocols and Standards?
- Bluetooth
- Ethernet 802.11x
- Radio Frequency Identification (RFID)
How does Radio Frequency Identification work?
It uses radio waves to transmit signals that activate the tag. Once activated, the tag sends a wave back to the antenna, where it is translated into data.
Name a Wired Communication Protocol.
Ethernet 802.3
What is Internet Protocol (IP)?
A set of rules that dictate how data should be delivered over a network and the internet.
What is Transmission Control Protocol (TCP)?
TCP works with IP to send packets over a network. TCP divides data into packets and gives each packet a header. TCP checks that all packets were recieved assembles it back into a file.
What are differences between IPv4 and IPv6?
IPv6 is an upgraded version of IPv4. It has 128 bits instead of 32 bits. Has a simpler header format. This means less address collisions and more efficient routing. Has built-in encryption.
Describe Domain Name System (DNS).
An Internet service that translates domain names into IP addresses.
Describe Dynamic Host Configuration Protocol (DHCP).
A protocol for assigning dynamic IP addresses to devices on a network. Automatically assigns IP addresses to new devices.
List methods used to ensure the security of networks.
- Firewalls
- Anti-Virus Software
- Password and Network User Policies
- Authentication
- Encryption
What is Anti-Virus Software?
- Software designed to detect and/or destroy computer viruses
- Scans downloaded programs and compares to viruses
What are Password and Network User Policies?
A set of rules that govern access to information, traffic routing, use of passwords and encryption.
What is Authentication?
Authentication is a method of protection, which verifies the identity of a user, before allowing data to be accessed.
What is Encryption?
Encryption is used to protect data from being stolen by scrambling it using algorithms.
List some strategies used to compromise the security of networks?
- Denial of Service
- Back Doors
- IP Spoofing
- Phishing
What is a Denial of Service Attack?
A type of cyber attack designed to disable, shut down or disrupt a network, website or service. Overloads the network with too much network traffic.
What are back doors?
Back doors are instructions that allows users to bypass security controls when accessing a program, computer, or network.
What is IP Spoofing?
The creation of IP packets with a false IP address to impersonate another computer system.
What is Phishing?
Phishing is a way of stealing personal information by tricking people into sending their personal details.
Describe Carrier Sense Multiple Access with Collision Detection (CSMA/CD).
- Computer will send data on an idle wire and listen for a collision.
- If a collision is detected will try again after a random amount of time.
- Only used on old wired networks.
Describe Carrier Sense Multiple Access with Collision Avoicance (CSMA/CA).
- Tries to avoid collisions.
- Will only transmit when there are no other transmissions.
- Will send again if reciever does not respond.
What is a Parity Check?
- Both computers agree to have an odd or even amount of 1 bits.
- One bit is used as a parity bit to ensure that the total number of 1 bits is odd/even.
What is a Checksum?
- Both computers agree to a divisor.
- The sum of bits is divided and the remainder (checksum) is sent along with the message.
- The checksum can be re-computed and crosschecked at the destination.
What is a Storage Area Network (SAN)?
- A special high speed network that stores and provides access to large amounts of data.
- All Devices are interconnected.
- Secure, fast and huge capacity.
What is a Network Attached Storage (NAS)?
- Stored in a centralised location on a network.
- Has a single point of failure.
- Remote access, scalable and reliable.
What are some factors influencing the performance of a network?
- Bandwidth - Amount of data travelling.
- Network Design - Efficiency of network.
- Excess Broadcast Traffic - Too much traffic.
- Viruses and DOS Attacks - Designed to slow down network.
- Data Collisions - Data has to be resent.
