Network Flashcards

Riley Loades
Flashcards by , created 2 months ago

GCSE Computer Science (Paper 1) Flashcards on Network Flashcards, created by Riley Loades on 05/12/2019.

Riley Loades
Created by Riley Loades 2 months ago
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GCSE Subjects
OCR gcse computer science
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Question Answer
Explain LAN and WAN? A LAN covers a small geographical area located on a single site. It is owned by the organisation that uses it. A WAN connects LANs that are in different geographical locations. A WAN is purchased from a telecommunication company (third party) who own and manage the WAN.
Explain the factors affecting Network Performance? Bandwidth - the amount of data that can be transferred in a given time. The greater the bandwidth, the better the network performs. The amount of Devices and usage can cause congestion and slow the network. Wired connections are generally faster and more reliable than wireless. Wireless performance is affected by the range, interference from other devices and physical obstacles. Hardware and Topology can also have a large effect on the network.
Explain the types of Network Hardware? NIC - A Network Interface Controller allows a device to connect to a network. Switches - These connect devices on a LAN, by receiving data from one device and transmitting the data to the device on the network with the correct MAC address. Routers - These are responsible for transmitting data between networks, and have a crucial role on the Internet, directing data to their destination. They are used to connect the LAN to the Internet, and most 'home' routers are a router, switch and WAP all-in-one.
Explain the types of Network Cabling? Ethernet Cables - 'Twisted pair' cables, containing four pairs of copper wires, that are twisted together to reduce internal interference. Coaxial Cables - A single copper wire surrounded by a plastic layer for insulation and a metallic mesh, which provides shielding from outside interference. Fibre Optic Cables - These transmit data as light, that run at a high performance, making them expensive. They don't suffer from interference and can transmit over very large distances without loss of signal quality.
Explain Wireless Networking? Wireless Networks use radio waves to transmit data. Wi-Fi comes in two frequency bands - 2.4 GHz and 5 GHz. These bands are split into numbered channels that each cover a small frequency range. Wi-Fi performance is affected by interference between networks using overlapping channels.
Wi-Fi Frequency Bands 2.4 GHz and 5 GHz 2.4 GHz has a greater range, so can serve devices across a wider area, and is better at getting through physical obstacles. 5 GHz is much faster when communicating over a short distance, and there are more non-overlapping channels, so there's less chance of interference from other devices.
Explain a Client-Sever and Peer-to-Peer Network? A Client-Server network is managed by a central server, and all the devices are connected to it. All of the files and software is stored centrally on the server. The client sends requests to the server. The server processes the request and responds. A Peer-to-Peer network is where all the devices are equal, connecting directly to each other without a server. The files are stored on individual devices and shared with each other.
Advantages and Disadvantages of a Client-Server Network A Client-Server network is easy to keep track of files, perform back-ups, install and update software, manage network security and servers are very reliable and always on BUT it can be expensive to set up and needs IT specialists to maintain the network and server, it is also server-dependent and the server could become overloaded with devices.
Advantages and Disadvantages of a Peer-to-Peer Network A Peer-to-Peer network is easy to maintain and there is no dependence on a server BUT there is no centralised management so everything has to be done individually, copying files between devices can create duplicate files so you can lose track easily, Peer machines are less reliable so data could be lost if one fails and machines are prone to slow down when other devices access them.
Explain the types of Topologies? (1/2) Star Topology - all devices are connected to a central switch or server that controls the network. Bus Topology - all devices are arranged in a line, where all devices are connected to a single backbone cable and send data in both directions, which can cause data collisions and slow the network.
Explain the types of Topologies? (2/2) Ring Topology - data flows in one direction around the ring, preventing data collisions, but only one device can send data at a time and data passes through many other devices before reaching its destination. Mesh Topology - all devices are either directly or indirectly connected to each other, without the need for one central switch or server. It sends data along the fastest route from one device to another. Full Mesh - all devices directly connect Partial Mesh - not all devices directly connect.
Explain what is meant by Protocol, MAC address and IP address? A Protocol is a set of rules for how devices communicate and how data is transmitted across a network. A MAC address is a unique identifier for every network-enabled device. It comes in 48 or 64 bit binary, but are converted into hexadecimal to make them easier to use, when they are read by LAN switches. An IP address is used when sending data between different networks, and aren't linked to hardware as they are assigned before the device can access the network. 128 bit is converted into 8 hexadecimal numbers and 32 bit is converted into 4 denary numbers.
Explain the types of IP addresses? Static IP addresses are permanent addresses. This is used when you don't want the IP address of something changing (websites) and they can be very expensive. Dynamic IP addresses are assigned when a device logs on to a network, so it will have a different IP address each time it connects. These are more cost-effective and can be reused.
Explain Data Packets and Packet Switching? (1/3) Data being sent between networks is split into equal-sized packets. The packet header contains the control information - destination address, source address and packet number. The packets payload is the data being sent. The packets checksum number is a form of validation that is checked by both devices to check that the data has been received correctly and not corrupted during transmit. The packet number is used to show the order of the data so it can be reassembled correctly when received.
Explain Data Packets and Packet Switching? (2/3) Packet Switching is used by routers to direct data packets on the Internet and other IP networks. The sending device splits the data into packets to be sent across the network, then each router reads the packet header and decides which way to send the packet, according to the IP rules. The way the data is sent changes depending on network traffic, and if the router receives too many packets, it may prioritise some over others.
Explain Data Packets and Packet Switching? (3/3) This causes the packets to likely arrive in the wrong order, so the packet number is used to reassemble them in the correct order. The receiving device periodically checks that it has all the data and if it doesn't after a certain time it will send a timeout message back to the sending device. When all the data is received and the checksums match, a receipt confirmation is sent to the sending device.
Explain the TCP and IP Network Protocols? TCP - The Transmission Control Protocol sets the rules for how devices connect to the network. It is responsible for splitting data into packets and reassembling the packets back into the original data, and checking that the data is correctly sent and delivered. IP - The Internet Protocol is responsible for Packet Switching.
Explain the other types of Network Protocols? (1/2) HTTP - The Hyper Text Transfer Protocol is used by web browsers to access websites and communicate with web servers. HTTPS - The HTTP Secure Protocol is a more secure version of HTTP, and encrypts all information that is sent and received. FTP - The File Transfer Protocol is used to access, edit and move files between devices on a network.
Explain the other types of Network Protocols? (2/2) POP3 - The Post Office Protocol (Version 3) is used to retrieve emails from a server. The server holds the email until it is downloaded, at which point it is deleted from the server. IMAP - The Internet Message Access Protocol is used to retrieve emails from a server. The server holds the email until you delete it - downloading it produces a copy. SMTP - The Simple Mail Transfer Protocol is used to send emails, and transfer emails between servers.
Explain the Network Protocol Layers? (1/2) A layer is a group of protocols, that have similar functions. The layers are self-contained and don't know what happened in other layers. Each Layer serves the layer above it. Layer 4 - Application Layer - It turns data into websites and other applications and vise-versa. (HTTP,FTP,SMTP) Layer 3 - Transport Layer - it controls the data flow. (TCP)
Explain the Network Protocol Layers? (2/2) Layer 2 - Network Layer - It makes connections between networks, directs data packets and handles traffic. (IP) Layer 1 - Data Link Layer - It passes data over the physical network, and is responsible for how bits are sent as electrical signals over cables, wireless and other hardware.
Explain the Internet, URLs and a DNS? (1/2) The Internet is a network of network - a WAN connecting devices and networks all over the world, based around the protocol TCP/IP. The World Wide Web (WWW) is a collection of websites that are hosted on web servers and accessed through the HTTP protocol.
Explain the Internet, URLs and a DNS? (2/2) URLs are addresses used to access web servers and resources on them. They use the HTTP/HTTPS protocol, the domain name of the website and a path to the specific page or file. A DNS (Domain Name Server) translates a websites domain name into its IP address, so you don't have to remember individual IP addresses.
Explain the Cloud and its Advantages and Disadvantages? The Cloud uses the Internet to store files and applications. The Cloud allows users to access files from any connected device, its easy to increase the capacity, no need for hardware or IT staff, the Cloud host provides security and backups and the Cloud software updates automatically BUT users need access to the Internet to access it, it is dependent on the host for security and backups, vulnerable to hackers, unclear who has ownership and subscription fees may be expensive.
Explain Virtual Networks, VPNs and Virtual LANs? (1/2) A Virtual Network is a network that is entirely software based. Several virtual networks can exist on the same physical network, so they all share the same hardware. Each virtual network has its own security, so that even people using the same physical network don't have access to the virtual network and may not know it even exists.
Explain Virtual Networks, VPNs and Virtual LANs? (2/2) A Virtual Private Network (VPN) is a type of virtual network that can be used to send data securely over a large network, like a WAN or the Internet. A Virtual LAN allows you to split a LAN into several separate networks using the same hardware.
Explain the types of Network Attacks? (1/2) A Passive Attack is where someone monitors data travelling on a network and intercepts any sensitive information. An Active Attack is when someone attacks a network with malware or other planned attacks. An Insider Attack is someone inside an organisation exploiting their network access to steal information.
Explain the types of Network Attacks? (2/2) A Brute Force Attack is a type of active attack used to gain information by cracking passwords through trial and error using automated software. A Denial of Service Attack is where someone tries to stop users from accessing a part of a network or website.
Explain Malware and the different actions of Malware? (1/2) Malware is installed on someone's device without their knowledge or consent. Malware can delete or modify files. Scareware - tricks users into following malicious links or paying the hacker by telling the user the device is infected with lots of viruses. Ransomware - encrypts all the files on a computer, and asking the user to pay for a decryption key.
Explain Malware and the different actions of Malware? (2/2) Spyware - secretly monitors users actions. Rootkits - alters permissions giving malware and hackers administrator-level access to devices. Backdoors - create a gap in someone's security to be used in the future.
Explain the ways Malware can access a device? Viruses - attach to certain files, and users spread them by copying infected files and activate them by opening these files. Worms - self-replicate without any user help so they spread very quickly, and exploit weaknesses in network security. Trojans - malware disguised as legitimate software. They don't replicate themselves, instead users install them not realising they have a hidden purpose.
Explain Social Engineering and the different types? Social Engineering is a way of gaining sensitive information or illegal access to networks by influencing people. This can be across the telephone where the social engineer attempts to gain someones trust so they will disclose sensitive information with them. It can also be done through Phishing, where emails or texts are sent as bait containing spoof versions of websites that ask people to update their information, so they enter sensitive information (login details) and give it all over to the criminal.
Explain SQL Injections and how they are used? Networks that make use of databases are vulnerable to SQL Injection attacks. SQL Injection attacks is when pieces of SQL (coding language) are entered into a websites input box to reveal sensitive information. This can be used if a websites input box doesn't have strong enough Input Validation that cant detect SQL statements, as it would give other peoples account information as well as their own.
Explain what a good Network Policy will have? A good Network Policy would involve the network being regularly tested and weaknesses being fixed, passwords to prevent unauthorised access, user access levels to limit the number of people with access to the sensitive information, install anti-malware and firewall software and encrypt sensitive data.
Explain the types of Network Protection? (1/3) Penetration Testing - organisations employ specialists to stimulate potential attacks on their network, to identify possible weaknesses so they can be fixed. Network Forensics - investigations carried out to find the cause of attacks on the network by capturing data packets, then analysing them to discover how the network was attacked and prevent any further attacks.
Explain the types of Network Protection? (2/3) Passwords - help prevent unauthorised users accessing the network. User Access Levels - control which group of users can access certain information/areas of the network. It helps limit the number of people with access to important data, reducing the chance of an insider attack.
Explain the types of Network Protection? (3/3) Anti-Malware - designed to find and stop malware from damaging a network and the devices on it. Firewalls - block unauthorised access by examining all data entering and leaving the network, blocking potential threats. Encryption - data in plain text is translated into cipher text which only someone with the correct key can access, so it can be sent across the network securely.