I.T. Information and resources

There is a lot of hype currently about A.I., however, the concept has been around for decades.  Before we dive into A.I., let me explain a related term; machine learning.   

• Machine Learning: is founded in the idea that we can use statistical analysis and mathematical modeling to look for patterns in data. We can then leverage computing power to look at a massive amount of data for patterns that are unexpected or lead us to new conclusions.  The best example I know of M.L. is the hurricane modeling NOAA does, especially the ‘spaghetti model’.  Each line is a probable outcome, and together, you can see the general ‘direction’ of the data.   

A.I. is this concept supercharged.  It combines a variety of fields to create devices that can reason, learn, and respond to input in new and unique ways.   

Using API's, scripts, and software to complete time consuming and monotonous tasks.  E.G. copying and pasting data from a ticketing system to an Excel sheet.      

 Bluetooth: used to connect two devices that are close to each other (~30 feet).   Common in wireless earbuds, wireless printers, etc.  Switches frequency hundreds  of times a second.  Devices have to be paired first 

 NFC (Near-Field Communication) 

connect devices over very short distances (~4 inches).  Commonly used for  mobile payments, like Google Pay 

 (Dynamic Host Configuration Protocol) -- allows for automatically assigning and reserving IP addresses for connected devices.  Can provide default gateway, domain name, DNS servers and time servers info to devices.   It is like the road map of the network.  

In a small office / residential setting DHCP is often handled by the router.  In an enterprise setting DHCP runs on a server instance and device connect and renew IP leases.   

 (Domain Name System) - provides a naming system for resources on the internet or other IP networks.  Converts a common name to the IP address of the resource.   It consists of a set of distributed servers maintain the domain name hierarchy and IP address spaces for the internet.   

• The ‘phone book’ of the internet.  URLs and email addresses use DNS to find the IP to find / send to.   
• A, AAAA records, SMTP mail (MX), domain name aliases (CNAME) records 
• Hierarchical structure – ascends from right to left.   www.ITSupport.teckworm.com 
• .com is the ROOT 
• .teckworm is subdomain 
• .departments is subdomain of teckworm 
• Uses a lot of caching servers to speed up requests, devices have DNS cache as well to speed up searches.   

Convert plain-text into a form that is unreadable without a decryption key. Ensures confidentiality and protects data at rest and it transit in data transmissions.  You can employ symmetric (where both sender / receiver have the same key) or public keys (where the only the receiver has the key to decrypt).

 TLS (transport layer security): uses encryption to provide secure communications  for services like email, VoIP phones, HTTPS requests and more.  Runs in the Application layer.  

 A network device (or software) that monitors network traffic and allows or blocks inbound / outbound traffic on the network based on rules.  They evaluate packets against an number of criteria: 

• Direction: inbound or outbound 
• Source and destination (IP Address) 
• Port 
• Protocol 
• Applications (not all firewalls) 
• Action: Allow / Deny / Drop / Forward for further inspection  

Firewalls are used to protect corporate networks from the public internet and on individual devices as part of the overall security suite.  

• Individual devices: should have a software-based firewall.  Windows has the “Windows Firewall with Advanced Security” built in.   

 Open Systems Interconnection model) - rules / concepts that are used in data transmission and troubleshooting network issues. 

There are 7 layers: 

• Application – Displaying and receiving information from the user.  Mail services, Directory services, remote file shares, etc. 
• DHCP, DNS, FTP, HTTP, HTTPS, IMAP, LDAP, SSH, TLS\SSL 
• Presentation – AKA Translation layer.  Data is formatted for the application, JPEG, GIF, TLS, SSL.  Handles encryption, compression.  
• Session – establish, manage and terminate sessions between two devices.   
• Transport – provides services for upper application layers.  E.G ACK for successful data transmission and re-transmit missing data.  Adds Port numbers to headers so data is handled by the right process (e.g. a webserver, port 80) Data is in segments.  Protocols are TCP, UDP, Error detection and correction 
• Network – transmission of data across networks, with devices like routers and switches.  Data is in packets.  IP address is used for routing. 
• Protocols: ICMP, IPsec 
• Data Link -- (DLL) ensures data moves between the nodes without errors using devices like switches.  Data is in Frames.  DLL uses MAC addresses to route. 
• Protocols: ARP, PPP, MAC 
• Physical – Physical connection between the devices, cords, hubs, modems, etc.   Information is in bits.  Manages things like Bit rate control, Transmission mode (full duplex, half duplex etc)  
• E.G. sending an email:  User types message in Mail application --> data is formatted and encrypted --> session established and managed --> data is segmented --> segments are broken into packets and routed --> packets are broken into Frames and sent to next device --> data is transmitted in bits.  Then REVERSE process to see the message.   

 Uses psychological manipulation (fear, urgency, empathy) to get a person to share sensitive data or take an action, like opening a link. Phishing is the most common social engineering attack.  

 A type of attack in which perpetrators create fake webpages, email addresses, phone number and domains that look legitimate, but are not.  Victims then divulge private information.    

 An attack in which the victim’s files are encrypted and the attacker demands payment to decrypt the files.  The file name extensions change and the victim can’t open there own documents.    

You need to know the basic parts of a computer.  There are some differences between laptop and desktop devices, this is hardware you’ll find in both.   

Motherboard: the motherboard contains, houses, or connects to all the other parts of the computer.  Things like the CPU and RAM are directly connected to the motherboard, while other devices, like power supplies connect to it.  The motherboard is covered in wires, resistors and components.     

CPU: central processing units is like the ‘brain’ of the computer, executing code at the binary level from the instructions it is given. 

GPU: graphical processing unit is specifically designed to handle computer graphics.  Modern video and gaming demands require a lot of comput power to meet, so GPUs were developed to provide smooth graphics.   

PCIe: Peripheral Component Interconnect Express are slots on the motherboard you can plug memory and other cards into.  GPU’s are plugged into a PCIe slots in desktop devices often and in laptops you can easily change out or add RAM with a PCIe slot.  

RAM: Random Access Memory is the short term memory storage for the  

 (Application programing interface) enable disparate applications to communicate with each other and exchange data.  The API is the set of rules (or protocols) used to coordinate this exchange.  E.G. if you log into a website using a Google account to authenticate, that website is making and API call to Google. 

 Used to direct network traffic to the correct services, E.G. port 443 for HTTPS traffic.   

• Used in connection strings for access, like SQL queries (Object Connector in SSMS) 

 Think back to the OSI model and how data flows from outside a network, to a connected device, and back out again (see OSI model above).  The network is all the devices and software running to make that function.  From cables coming into the building from the internet provider, to switches to route data, access points to provide a wireless connection, and firewalls on client device to filter packets.   

• Switch: a hardware device with many ports, it routes the data to where it needs to go 
• VLAN : on a switch you can logically group ports together for management or security purposes.  For example, you put all your security cameras on one VLAN and block access so malicious actors can’t access them remotely.   
• VPN: virtual private networks create a secure, encrypted connection between a device and a remote server (or two devices) .  Workplaces often use them to protect data.   
• MDF / IDF : The Main Distribution Frame (MDF) is the main junction between the corporate network and the external internet provider.  It consists of switches, often includes firewalls and hardware built to handle lots of traffic.  An Intermediate Distribution Frame is a secondary server rack for specific parts of a building.  There is often one on each floor of a building.  All the IDFs connect to the MDF for an external internet connection. 

Many of the things we do on computers, like checking email or browsing the web, rely on services running as background processes. These services each have a specific set of rules (protocols) that govern how they work.  Protocols are what define how data is sent, received and encapsulated in transit.  Also, most protocols use a specific port number to communicate on.   

Here are some of the most important ones: 

• ARP: (address resolution protocol) is used to map IP addresses to MAC addresses, basically matching up devices IDs to their IP address so packets can route to the correct place. Networking devices keep a mapping (ARP table) of this information that can get corrupted.  
• FTP: (file transfer protocol) is used to transfer files from servers to client devices.  New systems, like SharePoint, are being used instead of FTP, but it still widely used.   
• DNS: (Domain name system) is what allows us to find websites based on their common names, instead of an IP address.  For example, when I search for ‘Google.com’, DNS works to translate that into 8.8.8.8 so my web browser can connect.    DNS is often compared to a phone book, letting you find out what number (IP address) is assigned to a given place (domain name) 
• DHCP: (Dynamic Host Configuration Protocol) provides a way to manage the IP addresses for the computers and devices that connect to the network.  Every device that connects needs its own unique IP address and there is no way to realistically manually edit and update the IP address for even a small organization.  Among other things, DHCP allows you to reserve addresses and assign them so they don’t change.  This is useful for things like printers and routers that you want to keep a persistent IP address assigned to.  

SaaS, Paas, IaaS: these refer to how cloud providers deliver products to their customers and how much management and updating you’re responsible for as the network administrator. 

• SaaS: (Software as a Service) Updates, maintenance, and management is handled by the provider, as the admin you just make accounts.  These services are usually accessed through a web portal, with nothing to install on the local devices.  An example is an email service like Gmail, you just log into it and don’t have to manage the service at all, that is Google responsibility. 
• PaaS: (Platform as a service) provides the hardware and software environment to run and manage their own applications and data in the cloud.  For example, a Virtual Desktop environment that provides the CPU, RAM and operating system to work in.  As the Admin, you’d configure the environment, like a custom background and what apps are available for users.   
• IaaS: (Infrastructure as a service) provides the basic infrastructure services that business's need, like compute, storage, and networking  resources.  Admins install the operating system, custom apps and configure the environment as needed.  

 Uses radio waves to provide wireless network connection for devices.  Almost all personal devices that connect to the internet have a wi-fi cards inside.  To provide Wi-Fi to client devices, you install access points (AP) throughout the building.  Devices need to be no more than about 100 feet away from the AP, and less with walls and obstacles in the way.   

There are two primary wavelengths used in wifi set ups, 2.4 Ghz and 5 Ghz, and a number of common bands used, 802.11a, 802.11b, 802.11g and 802.11n.   

**For the Comptia exams, you’ll need to know the speeds and reach of each of these bands. 

 Virtual private networks create a secure, encrypted connection between a device and a remote server (or two devices) .  Workplaces often use them to protect data.    

Each device that connects to the internet needs a unique IP (internet protocol) address so it can receive and send data.  They consist of 4 groups of numbers separated by a period, e.g. 192.168.4.26.  Often, you create a range of addresses (called a subnet) to logically group devices and manage them more easily, or to keep different subnets isolated from each other / the public internet.  

Running a holiday sale or weekly special? Definitely promote it here to get customers excited about getting a sweet deal. 

• HDMI:  video cable used to connect computers to monitors and devices to TVs.  Blue Ray players, gaming systems, TVs, and projectors all use HDMI cords.  The ports are wider and narrower, with fluted edges. 
• USB: (universal serial bus) ports are the rectangular ports on laptops and desktops that peripherals devices plug into, like mice, keyboards and headsets.  USB flash drives are another common use of USB ports as well.  
• USB-C:  a newer and smaller version of USBs that support audio, video, docks and charging.  Newer monitors support USB-c and most cell phones use it for charging and data transfers with a cord.   
• ***Not to be confused with Thunderbolt cords – these cord have the same connectors  and fit into USB-C ports, but support much higher speeds.  You often find these in Apple devices and have a little lighting bolt near the port. 
• DisplayPort: used to connect computers to monitors.  The cords look similar to an HDMI cord.  It is rectangular with just one corner cut down.  DisplayPort cords support higher resolution and refresh rates than HDMI cords.  
• DVI-D: (digital visual interface) cords are older cords used to connect monitors to laptops and desktops.  They are wide and have number of pins. They often screw in like VGA cords.   
• VGA: (video graphics array) were the primary cords to connect desktop computers and monitors for a long time.  They are an analog interface and have a 15 PIN connector that screws into the port.