2.0 Networking! Flashcards
(83 cards)
1
Q
What is IP? And what does IP stand for?
A
IP stands for Internet Protocol. IP is the protocol by which data is sent from one computer to another on the internet.
IBID: IP is a set of rules that allows computers and other devices to communicate over the Internet.
There are several types of Internet Protocols including TCP, UDP, FTP, HTTP, HTTPS, SMTP etc. etc.
Each one has a specific purpose.
2
Q
What is TCP? What does TCP stand for?
A
TCP stands for Transmission Control Protocol.
Referred to as a “Connection oriented” protocol because there is a formal way to set up the connection and to close the connection with another device.
Considered a “Reliable” form of communication because TCP sends and acknowledgement when data is received.
3
Q
What is UDP? What does UDP stand for?
A
UDP stand for User Datagram Protocol.
Considered a “Connectionless” protocol.
- No formal process to start communication or tear down the connection with another device.
Considered “Unreliable” form of communication because the receiving device does not send acknowledgements that data was received.
-No error recovery, no reordering of data retransmissions
-No flow control. The sender determines how fast data is sent.
** Very little overhead, used for real-time communication like voice (VoIP) and video streaming
4
Q
TCP IP vs. UDP IP
A
TCP - Transmission Control Protocol
Primarily used for reliable data transmission, ensuring all packets are received in order
-formal process for setting up connection and tearing down connection after conversation is over.
-can handle errors, out-of-order messages and retransmission
-Flow control - the RECEIVER can manage how fast data is sent - tell the sender to speed up the data or slow down the data.
UDP - User Datagram Protocol
Preferred for applications requiring low latency, like streaming video, as it prioritizes speed over guaranteed delivery (Low latency means small to no delay in sending and receiving the packet of data.)
- no formalized process to open the connection or tear it down after convo is over.
-no error handling, reordering of packets or retransmission
- Sender determines how fast data is sent, even if they are sending it too fast for receiver to receive it.
5
Q
What is Latency?
A
Latency is the time it takes for a packet of data to go from source to destination. Latency is measured in milliseconds. Just 50 milliseconds of latency —less than one-tenth of one second — can result in poor network and application performance
6
Q
Can an application keep track of what info was received and what was not if using UDP?
A
Yes, even tho UDP doesn’t send an acknowledgement, the application using the data can do error handling and determine if it wants data to be resent.
7
Q
HTTP or HTTPS
A
HyperText Transfer Protocol OR HyperText Transfer Protocol Secure -
The protocol used for transferring web pages between servers and clients. This uses the TCP protocol.
8
Q
What is SSH? Is it UDP or TCP?
A
SSH - Secure Shell. It is a TCP technology
9
Q
FTP
A
File Transfer Protocol
The protocol that enables file transfer between devices, allowing users to upload and download files.
One of the oldest protocols.
10
Q
SMTP
A
Simple Mail Transfer Protocol -
Internet protocol that handles the sending of emails between servers
11
Q
DNS
A
Domain Name System - -
Internet protocol that translates human-readable domain names into machine-readable IP addresses
12
Q
bit vs. byte
A
bit – the smallest unit of
data. A bit is either a 0 or a 1.
0 means off, no, false
1 means on, yes, true
Byte – consists of 8 bits! It’s often used to represent a single character or a small amount of data.
13
Q
how many addresses are on a “packet” that is sent over the internet?
A
Each IP packet will contain both the IP address of the device sending the packet and the IP address of the intended recipient
14
Q
IPv4 & IPv6
A
- The fourth version of IP (IPv4 for short) was introduced in 1983.
- There are only so many possible permutations for IP addresses and the supply of available IPv4 addresses has become depleted.
- IPv6 addresses have many more characters and thus more permutations;
- IPv6 is not yet completely adopted, and most domains and devices still have IPv4 addresses.
15
Q
What’s in an IP header?
A header is attached to every IP packet.
A
In total there are 14 fields for IPv4 headers - although one of them is optional
An IP header is just a series of bits (ones and zeros), and it records several pieces of information about the packet, including the sending and receiving IP address. IP headers also report: Header length,
Packet length, if a packet is fragmented, which transport protocol is being used (I.E. TCP, UDP) etc. etc. etc.
16
Q
What is packet fragmentation?
A
Packet fragmentation refers to the process of dividing an IP packet into smaller fragments when the packet size exceeds the maximum transmission unit (MTU) of the network path.
These packets are then reassembled when the packets reach their destination.
17
Q
What are the 14 fields in an IPv4 header?
A
- Version: which IP version we are using (always 4 for IPv4)
- Header Length: tells us the length of the IP header . . . This field is also called the Internet Header Length (IHL).
- Type of Service aka Differentiated Services Code Point (DSCP): used for VoIP?
- ECN-This field allows end-to-end notification of network congestion without dropping packets.
- Total Length: Total size of the IP packet (header and data) in bytes.
- Identification: each fragmented packet will use the same 16 bit identification number to identify to which IP packet they belong.
- IP Flags: These 3 bits are used for fragmentation:
1st is always set to 0.
2nd is called the DF (Don’t Fragment) bit and indicates that this packet should not be fragmented.
3rd is called the MF (More Fragments) bit and is set on all fragmented packets except the last one. - Fragment Offset: the position of the fragment in the original packet.
- Time to Live: Decremented by 1, each router the packet passes through. Once it hits 0 the router will drop the packet and sends an ICMP time exceeded message to the sender. It’s used to prevent packets from looping around forever
- Protocol: tells us which protocol is enapsulated in the IP packet, for example TCP has value 6 and UDP has value 17.
- Header Checksum: Error detection for the header.
- Source Address: source IP address.
- Destination Address: destination IP address.
- IP Option: this field is not used often, is optional and has a variable length. An example of a possible option is “source route” where the sender requests for a certain routing path.
18
Q
200, 503 and 400 are examples of what?
A
HTTP response status codes
100 – 199 Informational
200 - 299 Successful
300 - 399 Redirection messages
400 - 499 Client error responses
500 - 599 Server error responses
19
Q
What is ICMP?
A
ICMP = Internet Control Message Protocol
used to communicate data transmission errors.
- ICMP sends messages from the receiver to the sender when data doesn’t arrive as expected. For example, if a message is too long or data packets arrive out of order, the receiver uses ICMP to inform the sender and request a resend.
- ICMP works on the network layer of the OSI model (layer 3) - same as IP
- - ICMP is also commonly used for pinging a device to check connectivity
20
Q
Explain how different network protocols and data are embedded
A
First layer - IP header and payload
2nd - in side that ^ payload you could have TCP header and TCP payload
3rd - inside that ^ payload you could have HTTP header and HTTP data
TCP and UDP are also called “transport layer protocols”
Sounds like 1st layer is IP and 2nd layer is TCP or UDP and 3rd layer is something like HTTPS, FTP, SMTP etc. I could be wrong on this, but that’s how it’s sounding.
21
Q
What are OSI Layers and how do they work?
A
There are 7 OSI layers.
1. Application Layer,
2. Presentation Layer,
3. Session Layer,
4. Transport Layer - (this is where TCP and UDP opperate)
5. Network Layer,
6. Data Link Layer,
7. Physical Layer
- Each layer communicates with the layer above and below it.
- Different network protocols operate at different layers of the OSI model.
- Data is encapsulated with additional information at each layer as it moves thru the stack until it gets to the physical layer where it is sent over wires or wirelessly.
On the receiving side - as you move thru the stack data is decapsulated (removed), until the data gets to the application where the application can use the data that is received.
22
Q
What are the 7 OSI layers? What does each layer do? What are examples of protocols that operate at that layer?
A
- <b>Physical Layer:</b>
Responsible for converting digital data into electrical signals that can be transmitted over a physical medium. \n
<b>Protocols:</b>RS-232, Ethernet, FiberOptic - <b>Data Link Layer:</b>
Manages error detection and correction within a local network(LAN), ensure data delivery on devices within the same network. Deals with MAC addresses <b>Protocols:</b>Ethernet(IEEE802.3), Wi-Fi (802.11), PPP, et al. - <b>Network Layer:</b>
Routes packets by determining the best path to reach the destination. Routing data packets between different networks. Deals with IP addresses <b>Protocol:</b>Internet Protocol (IP) mainly, but also ICMP - <b>Transport Layer:</b>
Ensures data delivery by managing the flow of data segments, including error checking and retransmission if needed.
<b>Protocols:</b> TCP, UDP, - <b>Session Layer:</b>
setting up, coordinating, and terminating sessions between applications on different devices.
<b>Protocols:</b> NetBIOS, AppleTalk(ASP), PPTP, etc. - <b>Presentation Layer:</b>
converts data from a complex format into one that the application layer can understand, including data formatting, compression, encryption, decryption and translation
<b>Protocols:</b>JPEG, SSL (Secure Socket Layer), TLS (Transport Layer Security), GIF, ASCII etc. - <b>Application Layer:</b>
Directly interacts with user applications, providing network services like email, file transfer, and web browsing.
<b>Protocols:</b>HTTP (Hypertext Transfer Protocol), FTP (File Transfer Protocol), SMTP (Simple Mail Transfer Protocol), DNS (Domain Name System), SSH (Secure Shell), POP3 (Post Office Protocol 3) etc.
23
Q
What is multiplexing (when it comes to networking)?
A
Having many applications on your system talking to a separate servers simultaneously. This is accomplished thru network protocols (like UDP&TCP) that keep the data separate from each other, but also allow data to go EXACTLY where it’s supposed to.
24
Q
What are DHCP and TFTP and what do they have in common?
A
DHCP = Dynamic Host Configuration Protocol
TFTP = Trivial File Transfer Protocol
These are both “connectionless” protocols that use UDP (rather than TCP) at the transport layer.
With UDP communication, the application keeps track of what data was received and if they are missing data, or a lower level protocol (like DHCP) keeps track of missing data and asks for a resend.
25
IP address
Just like every house has an address, every computer on the internet has an address. This is the IP address.
26
IP address vs. MAC address
An IP address identifies a device globally on the internet, while a MAC address identifies a device only on its local network (LAN).
** Scope & Usage: IP address is global, while MAC address is local.
** Assignment: IP addresses can be dynamically assigned by a network, while MAC addresses are permanently assigned by the device manufacturer.
Each device on a LAN has a unique IP, but the first part of the IP address (network portion) will be the same for all devices on the same LAN.
27
IP addresses vs. ports
An IP address identifies a specific device on a network, while a port number identifies a specific application or service running on that device. IE, a port number tells you which application on that device to send data to
A port is essentially a virtual "door" on a device that directs incoming data to a particular application.
-It's like a street address, and a port number is like an apartment number within that building.
**Sockets - an IP address & port number together form a "socket".
When you need to connect to a specific service on a device, you use both the IP address and the port number, which is often written together as "IP address:port number". For example: 192.168.1.10:80 - the first 9 numbers are the IP address and "80" is the port number.
** Port numbers are usually assigned to specific duties/services/applications:
Usually port 80 is used for web traffic and port 22 for SSH.
Example: you want to access a website on a server with the IP address "192.168.1.10". To reach the website, you would use "192.168.1.10:80" because port 80 is typically used for web traffic.
28
What is multiplexing? How does it use ports?
Multiplexing is the process of combining multiple data streams into a single connection. In TCP/IP, it is achieved through the use of ports. By assigning unique port numbers to different applications or services, multiple data streams can be transmitted over a single connection. And then broken down into different ports once the data arrives at the receiving device.
Ports determine what service/application on a server will receive the data
Ports are used in TCP and UDP data transmission
Specific ports are usually associated with specific types of data/services/applications. 80 is usually for HTTP and 443 is for HTTPS.
29
ephemeral defenition
ephemeral - lasting a very short time
30
ephemeral vs. non-ephemeral ports
Non-ephemeral ports are permanent port numbers that are assigned to a specific application or service and do not change. For example, a web server will always use port 80 to provide its services
** Most servers (services) will use non-ephemeral port numbers, aka "well known" port numbers. This is standard, but there are exceptions.
** most clients will use ephemeral ports when communicating with a server.
Ephemeral ports are temporary, short-lived ports assigned by the operating system for the duration of a communication session. The OS randomly selects these ports from a predefined range. Once the communication session is completed, the ephemeral ports are returned to the pool for future use.
31
What is the range of port numbers ?
What ranges are typically used for what activities?
Port numbers range from 0 to 65,535:
Ports 0–1023:
System or well-known ports (non-ephemeral) - usually it will be a well known port number on the server side of things
Ports 1024–65,535:
temporary or ephemeral ports - assigned by the client in real-time. Used for a communication session and then next time you open communication with that server, it will pick a new port number from the pool of available numbers
32
what is a port scanner
scans a server and finds all the open ports
33
TCP vs. UDP port numbers
Is a TCP port 80 the same as a UDP port 80?
NO!
TCP port numbers aren't the same as UDP port numbers.
This means that there could be a TCP service running on port 80 and a completely different service running on UDP port 80. But ppl don't tend to do this in normal operation (use the EXACT same number) because it's confusing.
34
What is happening in this scenario:
Server:
10.0.0.2
Client (laptop):
10.0.0.1
Source IP: 10.0.0.1
Destination IP: 10.0.0.2
TCP Source port: 3000
TCP Dest. Port: 80
HTTP data
The client (the laptop) is sending http data to the server. Http data is sent using the TCP protocol so that's why we're using TCP ports. If we were sending VoIP data, we would be using UDP ports.
notice how the server port is 'well known' and the client port is pretty random
35
What is the road, house, room metaphor for networking?
The network is like a series of roads that connect with each other.
The IP packets are like trucks that take things from one place to another.
The boxes inside the truck are the payload inside IP packets. One box might be UDP data, another box might be TCP data.
Inside the boxes is application data.
The IP address - Every device has an IP address just like every house has a street address.
Port number - each port is like a room in the house. Some data will go to this port and some data will go to that port. just like some boxes will go in the kitchen and some will go to the bedroom.
36
what is encapsulation and decapsulation
Encapsulation is nesting different types of data inside other types of data. Or nesting application data inside a certain protocol that is then encapsulated in another type of protocol.
Encapsulation is packaging the data and decapsulation is unpacking the data.
37
2.1
What protocol usually runs on
ports 20-21?
FTP - File transfer Protocol
38
Why is it important to know commonly used port numbers
1. Firewall configuration - port numbers are commonly used to allow or block network traffic.
2. When you're trying to troubleshoot a communications issue with a service/server.
39
2.1
What is FTP?
What port does it usually run on?
What is it used for? What does it do?
FTP = File Transfer Protocol
TCP Ports 20-21
There are different types of FTP and they may use one or both of these ports.
Port 20 is used for active mode data
Port 21 is use for control/admin
Transfers files between systems
-Can authenticate with password and username
-Some systems allow use of generic/anonymous login so that anyone can gain access
- FTP can also list files in a directory, add files, delete files and do other administrative functions.
40
2.1
What protocol usually runs on
ports 22?
Secure Shell (SSH)
41
2.1
What is SSH?
What port does it usually run on?
What is it used for / What does it do?
SSH = Secure Shell
TCP Port 22
Used to connect to a remote device and make configuration changes at the command line.
Encrypted from end to end
Looks and acts the same as Telnet, but telnet is not encrypted so ppl no longer use Telnet as much
42
2.1
What protocol usually runs on
ports 23?
Telnet
43
2.1
What is Telnet?
What port does it usually run on?
What is it used for? What does it do?
Telnet
TCP Port 23
Used to connect to a remote device and make configuration changes at the command line.
Used in older systems - is not longer used because SSH is preferred because SSH is encrypted and Telnet is not.
Sometimes unencrypted communication is referred to as "in-the-clear" communication.
44
2.1
What protocol usually runs on
ports 25?
Simple Mail Transfer
Protocol (SMTP)
45
2.1
What is SMTP?
What port does it usually run on?
What is it used for? What does it do?
SMTP - Simple Mail Transfer Protocol
TCP Port 25
- Server to Server email transfer
- SMTP is also used to send mail from a mobile device to an email server. (You might configure SMTP on a device)
- To RECEIVE emails as a client(ie not a server) - usually we use other protocols like POP3 and IMAP.
46
2.1
What protocol usually runs on
ports 53?
Domain Name System (DNS)
47
2.1
What is DNS?
What port does it usually run on?
What is it used for? What does it do?
DNS = Domain Name System
UDP Port 53
Converts/translates names (like ellenstucki.com) to IP addresses
48
2.1
What protocol usually runs on
ports 67/68?
Dynamic Host
Configuration Protocol (DHCP)
UDP Port 67
UDP Port 68
49
What is a DHCP server and how does it work?
DHCP = dynamic host configuration protocol
a DHCP server - can be a stand alone server or appliance, can also be integrated into a small office/home office router
1. On this server is a pool of available IP addresses and when a device connects to the network the device requests an IP address and configuration parameters from that pool
2. The device receives the IP address and it "leases" that IP address for a certain amount of time. When the time is up it can renew the lease or return it to the IP address pool for someone else to use.
DHCP reservation
1. Network administrators can also use DHCP to manually configure IP address that will ALWAYS be assigned to certain devices. This is called reserving an IP address
2. They assign the IP address to the MAC address (MAC addresses are typically hardcoded into a device's hardware and remain constant)
3. Typically used if you have a printer or server and you want it to ALWAYS have the same IP address b/c ppl on the network are constantly trying to connect to it.
50
2.1
What is DHCP?
What port does it usually run on?
What is it used for? What does it do?
DHCP = Dynamic Host Configuration Protocol
UDP Ports 67-68
Configures computers (like my computer) automatically when I connect to the network
Configures your system with host IP addresses automatically behind the scenes
Must have DHCP server for this to work.
See the other flashcard for a detailed description of how this works.
51
2.1
What protocol usually runs on
ports 80?
80 – Hypertext Transfer
Protocol (HTTP)
52
2.1
What is HTTP?
What port does it usually run on?
What is it used for? What does it do?
HTTP = Hypertext Transfer Protocol
TCP Port 80
Communicates with browsers - sends info to and from browsers
NOT encrypted - aka 'in the clear' communication
53
2.1
What protocol usually runs on
ports 110?
110 – Post Office Protocol 3 (POP3)
54
2.1
What is POP3?
What port does it usually run on?
What is it used for? What does it do?
4 distinctions
Post Office Protocol v. 3
TCP Port 110
Protocol to RECEIVE email from an email server (on your computer or mobile phone)
1. Client-Side Storage: Emails are downloaded to the user's device (computer, phone, etc.) and typically removed from the server.
2. One Device Access: Primarily designed for accessing emails on a single device.
3. Offline Access: Downloaded emails can be accessed without an internet connection.
4. Less Server Load: Reduces the load on the email server as emails are stored locally.
55
2.1
What protocol usually runs on
ports 143?
143 – Internet Mail Access
Protocol (IMAP) - currently on version 4 -- so IMAP4
56
2.1
What is IMAP?
What port does it usually run on?
What is it used for? What does it do?
2 distinctions
IMAP = Internet Mail Access Protocol
tcp Port 143
Protocol to RECEIVE email from an email server (on your computer or mobile phone)
1. Emails are stored on the server but can be accessed from multiple devices.
2. Synchronization: Changes made on one device (reading, deleting, moving emails) are changed on the server reflected across all devices.
--Just as a remind an email client is what the user uses - it is gmail or Outlook or YahooMail
57
Compare and contrast IMAP4 with POP3
IMAP4:
1. Server-Side Storage: Emails remain on the email server, allowing access from multiple devices.
2. Synchronization: Changes made on one device (reading, deleting, moving emails) are reflected across all devices.
3. Flexibility: Ideal for users who need to access their email from various devices or locations.
4. Potential for Server-Side Issues:
If the server experiences problems, data loss is possible unless backups are in place.
POP3
1. Client-Side Storage: Emails are downloaded to the user's device (computer, phone, etc.) and typically removed from the server.
2. One Device Access: Primarily designed for accessing emails on a single device.
3. Offline Access: Downloaded emails can be accessed without an internet connection.
4. Less Server Load: Reduces the load on the email server as emails are stored locally.
58
2.1
What protocol usually runs on
ports 137-139?
137-139 NetBIOS = Network Basic Input/
Output System /
NetBIOS over TCP/IP (NetBT)
59
2.1
What is NetBIOS? NetBT?
What port does it usually run on?
What is it used for? What does it do?
NetBIOS = Network Basic Input/Output System
NetBT= NetBIOS over TCP/IP
udp port 137 = runs the name service (like DNS)
TCP port 139 - runs the session service (like SMB)
1. Name Resolution: NetBIOS provides a mechanism to resolve computer names into network addresses, (like DNS)
2. Connection Services: communication services for applications to establish sessions and exchange data.
3. Legacy Support: NetBIOS was widely used in older Windows operating systems and applications. While still present in some systems, modern systems are more likely to use the more secure and more efficient protocols SMB and DNS.
4. NetBIOS over TCP/IP:
NetBIOS was actually an API that worked on very small LANs - wasn't really a protocol. NetBT is a protocol that was invented to allow NetBIOS to run over TCP networks (which are the dominant networks today.) IBID: NetBT allows modern networks to support older applications that were originally designed to use NetBIOS
5. Security Concerns:
Due to vulnerabilities, NetBIOS is often disabled in modern networks and SMB and/or DNS are used.
60
2.1 Compare and Contrast NetBIOS and NetBT
NetBios
1. NetBIOS is primarily an API that defines how applications can access network services like file sharing and printing.
2. Legacy system: It was designed for very small local area networks (LANs) in the early days of networking.
3. Its original implementations had limitations, particularly with routing and scalability.
4. Name-based addressing: NetBIOS relies on computer names (up to 16 characters) for addressing, rather than IP addresses.
NetBT (NetBIOS over TCP/IP):
1. NetBT was developed to allow NetBIOS applications to function on TCP/IP networks.
6. Name resolution: It provides a mechanism to map NetBIOS computer names to IP addresses, enabling communication between NetBIOS-based applications and the broader TCP/IP network.
7. Uses TCP/UDP ports: NetBT utilizes specific TCP and UDP ports (137, 138, and 139) for name resolution, datagram, and session services.
8. Compatibility:
NetBT is crucial for compatibility with older applications that still rely on NetBIOS for network communication.
61
2.1
What protocol usually runs on
ports 389?
389 – Lightweight Directory
Access Protocol (LDAP)
62
2.1
What is LDAP? LDAPS?
What port does it usually run on?
What is it used for? What does it do?
LDAP = Lightweight Directory Access Protocol
LDAP = Lightweight Directory Access Protocol SECURE
tcp Port 389
- protocol used for accessing and managing directory information services over a network. Think of it as a phone book for your network, allowing applications to easily find and use information stored in a central location
1. LDAP enables applications to interact with directory services, which store information about users, systems, and other network resources.
2. lightweight, efficient data retrieval,
3. open and vendor-neutral, meaning it can be used with various directory services and operating systems.
4. widely used for user authentication, single sign-on, and managing user accounts, passwords, and other directory information.
5. Microsoft's Active Directory is an LDAP-based directory service, meaning it uses the LDAP protocol for accessing and managing directory information.
6. How it works: Applications send LDAP requests to a server which then responds with the requested information
63
2.1
What protocol usually runs on
ports 443?
443 – Hypertext Transfer
Protocol Secure (HTTPS)
64
2.1
What is HTTPS?
What port does it usually run on?
What is it used for? What does it do?
HTTPS = Hypertext Transfer Protocol SECURE
TCP Port 443
Communicates with browsers - sends info to and from browsers
Differs from HTTP in that all information in the packet with be encrypted
65
2.1
What protocol usually runs on
port 445?
445 – Server Message Block (SMB) -- aka
Common Internet File System (CIFS)
66
2.1
What is SMB? CIFS?
What port does it usually run on?
What is it used for? What does it do?
SMB = Server Message Block
aka CIFS = Common Internet File System
TCP Port 445
It enables applications on one computer to access files and resources on another computer as if they were local. Primarily used in Microsoft Windows environments, SMB facilitates communication between clients and servers for file access, printing, and other network services.
This is sometimes refered to as NetBIOS-less communication b/c it does not use NetBIOS.
67
Compare and contrast FTP vs. SMB
FTP is primarily used for transferring files between servers and client machines. SMB is used for sharing resources within a local network, such as files, printers, and serial ports
68
Is there a difference between SMB and CIFS?
Yes, CIFS is technically a dialect of the SMB (Server Message Block) protocol. CIFS (Common Internet File System) was a specific implementation of SMB, used in Windows 95 and 98. While the term "CIFS" is still used, modern Windows systems primarily use newer versions of the SMB protocol (2.0, 3.0 etc)
SMB and CIFS are still used interchangeably, especially in informal settings.
69
2.1
What protocol usually runs on
ports 3389?
3389 – Remote Desktop
Protocol (RDP)
70
2.1
What is RDP?
What port does it usually run on?
What is it used for? What does it do?
RDP = Remote Desktop Protocol
tcp Port 3389
- Remote control access of a separate machine
- Usually used on windows devices but there are clients that will allow you to connect with a windows machine from a linux box, android, iphone, AppleOS etc.
- Can connect and run an entire computer or just run a specific application on that computer.
71
2.2
what frequencies are most commonly used by wireless networks?
2.4 GHz: This band offers a longer range and better penetration through walls and obstacles, but it also has slower data speeds and is more susceptible to interference from other devices.
5 GHz: This band offers faster data speeds and is less crowded than 2.4 GHz, but it has a shorter range and is more affected by obstructions.
6 GHz: This band, introduced with newer Wi-Fi standards, offers even faster speeds and wider channels but with the shortest range.
72
What are the basics of radio frequencies and how they are used for wireless networking?
5 distinctions
1. Frequencies: Wireless networks use radio waves to transmit data. The number of cycles (oscillations) per second of these waves is measured in Hertz (Hz). A gigahertz (GHz) is one billion Hz. So 2.4 GHz frequency is 2.4 billion cycles per second.
2. Speed vs. Distance: Lower frequencies like 2.4 GHz offer longer distance but slower speeds, while higher frequencies like 5 GHz provide faster speeds with shorter ranges
3. Channels: Within each frequency band, the spectrum is further divided into channels. These channels allow multiple devices to connect to the same network without interference.
4. Interference: Microwaves, Bluetooth devices, and other Wi-Fi networks can interfere with 2.4 GHz signals, potentially slowing down or disrupting your connection.
5. Bandwidth: Bandwidth refers to the amount of data that can be transmitted at a given time. Higher frequencies generally support higher bandwidths. (but higher frequencies go shorter distances)
6. Some devices can use different frequencies simultaneously.
73
What are wireless networking channels?
Frequency Bands, Channels and Bandwidth
1. Frequency Bands: Wi-Fi operates primarily on two frequency bands: 2.4 GHz and 5 GHz. (6GHz has been introduced)
2. Channels: Each frequency band is further divided into multiple channels. These channels allow multiple devices to connect without interfering with each other.
-- 2.4 GHz Band:
Offers 14 channels, but only channels 1, 6, and 11 are non-overlapping, meaning they can be used simultaneously without causing significant interference.
-- 5 GHz Band:
Provides more channels, typically 23 non-overlapping, offering more flexibility and less congestion.
3. Channel Width (aka Bandwidth): Channels can also have different widths (e.g., 20 MHz, 40 MHz, 80 MHz, and 160 MHz for Wi-Fi 6)
The higher the GHz, the more bandwidth you have and the more channels you can have. Also the wider the channels can be.
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What are the regulations regarding wireless frequencies
Each country has its own regulatory authority (e.g., FCC in the US, ETSI in Europe) that sets specific rules for Wi-Fi use.
Regulations specify
1. channel widths - how wide a channel is like 20MHz, 40 MHz etc.
2. allowed power levels
3. which frequency ranges can be used (2.4GHz, 5GHz etc.)
4. which channels can be used within the 2.4 GHz and 5 GHz frequency bands.
For example, in the US, only 11 channels are allowed in the 2.4 GHz band, while more channels are available in the 5 GHz band
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2.2
Who is the IEEE and what do they do?
IEEE = Institute of Electrical and Electronics Engineers
They create standards for wireless networks
The 802.11 committee is the committee that determines wi-fi standards. That is why wi-fi technology is sometimes referred to as 802.11
Everyone follows these standards.
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2.2
What are the different names for the different versions of Wi-fi?
802.11ac wi-fi 5
802.11ax wi-fi 6 and wi-fi 6E (extended)
802.11be wi-fi 7
future versions will increment accordingly.
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2.2
What is the Unlicensed ISM
2.4 GHz is sometimes referred to as the unlicensed ISM (Industrial, Scientific and Medical) band because you don't have to have a license to use frequencies in this band.
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2.2
What is bluetooth, how is it used?
Bluetooth is another wireless technology that is different from wi-fi (802.11)
It uses the 2.4GHz range
Maximum range for Bluetooth is about 10 meters - which is much smaller than wifi
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What does RFID stand for? and where is it used?
RFID = Radio Frequency Identification
Use in Access badges
Pet/Animal tracking
Inventory tracking
Anything that needs to be tracked
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2.2
How does RFID work w/out a battery?
The power from the radio frequency of the scanner is enough to power the RFID tag.
1. radio power is transmitted to the tag thru a scanner
2. radio frequency powers the tag and an ID code is transmitted back
3. The ID code is compared to information in a database to determine what that ID tag is referencing
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2.2
Do some RFID tags have batteries? Why?
Yes, some RFID tags have batteries.
Having a power sources which makes it so that you can scan that device from a longer distance away.
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2.2
What is NFC? how is it used?
NFC = Near Field Communication
Another type of wireless communication
It builds on the RFID technology - which is usually a one-way communication - NFC makes it a 2-way communication
Used in
1. Payment systems - credit cards and online wallets (apple pay etc.)
2. NFC sometimes helps a device connect to bluetooth or wi-fi
3. Can be used on your phone as an access card or ID card
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2.3
