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A+ (Peripherals, Networking, Hardware, Virtualization, Tools,…

- - - - USB-A
      - USB-B
      - USB-Mini-B
      - USB-C
      - USB-Micro-B
      - USB-3.0-Micro-B
  - - - PCIe X Displayport. Pretty much good for anything. Three versions. Thunderbolt 1 10Gbps over 2 channels. Thunderbolt 2 20Gbps over 1 channel and Thunderbolt 3 which is the same but at 40Gbps
    - - Proprietary to Apple. Thunderbolt for IOS. Essentially lightning is like USB-C for Apple IOS with Thunderbolt being the MAC equivalent.
      - Much slower than thunderbolt. Lightning is 5Gbps where thunderbolt is 40Gbps
  - - - Blue
        
        Means Recording devices (Auxiliary line in)
      - Green
        
        Front two stereo speakers are what this is used for.
      - Pink
        
        For microphones.
      - Grey
        
        Two more side speakers.
      - Black
        
        Rear Speakers.
      - Orange
        
        Centre channel (Subwoofers)
    - - S/P DIF (Sony/Phillips Digital Interface)
    - - Usually uses USB
  - - - Used for payment and high security situations.
    - - Swipe devices
    - - SD, micro SD, Olympus xD
- - - - Ethernet frame is made up of Destination MAC/ Source MAC/ Data/ FCS
    - - Hubs are repeaters where Switches are smart and use a MAC lookup table for speed.
    - - TCP packet is constructed in this order. Dest MAC / Source MAC / Dest IP / Source IP / Data / FCS
      - Any IP ending with a 0 is a network ID, anything ending with 255 is a broadcast address.
      - Net IDs and Subnet Masks
    - - Class A (1.0.0.0 to 126.0.0.0)
      - Class B (128.X.0.0 to 191.X.0.0)
      - Class C (192.X.X.0 to 223.X.X.0)
      - Class D (224.X.X.X for multicast)
      - Class E (240.X.X.X reserved addresses)
      - Private addresses
        
        Class A starting with 10
        
        Class B starting with 172.16 or 172.31
        
        Class C start with 192.168.X
      - Loopback address (127.0.0.1 in most cases)
        
        Refers to the specific system it is configured on [Self-reference] (often used for testing)
    - - Gateway routers use NAT for all devices connected to them
      - Uses a replacement External address when the packet passes through the router, this means the private IP addresses are hidden behind the gateway and all external packets go through the gateway router.
    - - Devices will make IP requests which target a DHCP server if there is one in scope. The DHCP server will dynamically allocate an address from a pool of addresses that it controls.
      - If a DHCP server is not present each device has APIPA which is a default protocol for obtaining an IP address in the absence of a DHCP server. APIPA always give 169.254.X.X address, which is a Class B address.
      - ipconfig /renew in windows will force new connection to DHCP server in the case of an issue.
    - - Future of network addressing
      - 8 groups separated by 7 colons.
        
        remove leading zeros in a group, if a number of 0s appear in a row you can describe that using a double colon like this ::.
      - Link-local address (fe80:0000:0000:0000:[Automatically generated second half])
      - Internet address (Global unicast address)
        
        Gives first half and generates second half of this address.
      - Can spin up multiple temp addresses for security.
      - Instead of subnet mask IPv6 has a prefix which is /64
      - 128 bit addressing scheme in hexadecimal notation
    - - Port listening software such as IIS or Apache are used to allocate and watch port numbers.
      - DNS utilizes port numbers tacced onto the end of the IP address so that the application can be found.
      - Port numbers go from 0-65535. There will always be a source and destination port as well as IP address.
      - OS handles port numbers.
      - All port numbers from 0-1023 are well-known ports. e.g. web, secure web.
        
        1024-49151 are registered ports. These are for other companies that aren't well known but have their own ports.
        
        49152-65535 are ephemeral ports. These are free ports used by the operating system for return ports in traffic.
      - Common numbers
        
        21-FTP
        
        22-SSH
        
        23-TELNET
        
        25-SMTP
        
        53-DNS
        
        80-HTTP
        
        110-POP3
        
        161/162-SNMP
        
        143-IMAP
        
        443-HTTPS
        
        3389-RDP
        
        137-139-NETBIOS/NETBT
        
        445-SMB/CIFS
        
        427-SLP
        
        548-AFP
        
        67/68-DHCP
        
        389-LDAP
    - - Server that translates domain names into public IP addresses for traffic processing.
      - Consists of root servers that qualify the root domain "."
        
        Under root servers are first level servers handling things like .com, .edu
        
        Lastly there are second level domains that handle application specific domain names.
      - If DNS server doesn't have a domain name, it will ping its closest root server which will direct the request down through the hierarchy to find the server for the Domain name that is requested.
      - If a Domain is found and used frequently the DNS server and localhost will both keep a copy of the IP conversion.
      - DNS has a 256 character limit. including dots this is an FQDN
      - Working with DNS
        
        DNS servers can fail. This is why alternate servers are useful, this can be configured statically.
        
        nslookup can be used for problem solving DNS issues
        
        DNS stores record. A regular record such as www. is an A record. MX is for mail servers and Cname records are for ip addresses with multiple names.
        
        nslookup can show us if a DNS timeout is occurring.
    - - TCP is a connection oriented protocol. Using handshakes for security / good for data transfer that doesn't require speed.
      - UDP is a connectionless protocol, good for streaming and speed but there is no handshake or verification.
      - ICMP is a single packet protocol. Ping is an example of an ICMP protocol packet.
      - These protocols can be separated using a PDU. An Ethernet frame is analysed from the outside. the IP packet is the overall frame without the IP addresses and FCS. Once inside a system we have port numbers and data left, This is called a TCP segment or a UDP datagram.
    - - Every device will be part of a workgroup in windows. Could also be a member of a domain, if this is the case it will say the domain in the about info.
        
        Workgroup vs Domain
        
        Workgroup is an organizational scheme. Domains are more complicated and they need a windows server system. These are called an Active Directory Domain. These are great for security but also very expensive.
        
        Could also have a Homegroup which is essentially a middle ground between a Workgroup and an ADD. Windows 10 does not support Homegroup.
    - - Used to interconnect LANs
      - Routing tables tell the router which interfaces to send packets through based on addresses.
      - Every router has a default gateway to the internet. In home this is usually the interface out to the ISP.
      - Home routers these days are usually a router, a switch and a WAP all in the one box. Up stream connections in these cases use DOCSIS.
      - Rollover cable is common for first setup on enterprise routers and web interfaces are the case for most modern home routers.
      - Config
        
        Basic
        
        Most routers are DHCP Clients same as a desktop.
        
        You can set the internal LAN IP for the router to be something different. This is for obfuscation mostly. Assuming everything is dynamic DHCP will handle the rest.
        
        Admin for usernames and passwords as well as local management. Can set a filter so that only a single PC can edit the router settings. Can also enable remote management from outside the LAN. DO NOT TURN ON REMOTE MANAGEMENT.
        
        Advanced
        
        QoS
        
        Can give certain IP or MAC addresses as well as ports extra bandwidth. Can also setup router so that extra bandwidth is given if a specific application is running.
        
        Need to know Up and Down link speeds for config.
        
        Can set QoS by port number for extra bandwidth for gaming.
        
        UPnP (Universal Plug and Play)
        
        Helps with network device identification.
        
        Link Layer Discovery should be setup for discoverability.
        
        SNMP
        
        Used to admin networks and see bandwidth and router filtering etc.
    - - Takes one physical switch and electronically turns it into 2 or more switches.
      - Must give a switch an IP for VLAN management (Managed Switch). Normally more expensive but has VLAN support
      - Often switches will have VLAN 1 and VLAN 2 by default.
    - - No connectivity
        
        Look at physical connections and make sure everything is connected. If it is its probably an IP addressing issue, especially if there are static addressing schemes on some devices.
      - IP conflict
        
        Two or more devices with the same IP.
      - Limited connectivity
        
        DHCP screamer, often related to APIPA addresses. If addresses are not APIPA but the IPs are different eg 192.168.4.X to 192.168.7.X this often means there's a rouge DHCP server.
      - Unavailable resources
        
        If you can get to the system, shared resources problem. if cant system issue.
      - Slow transfer speeds
        
        Often related to network card hardware capabilities. QoS can help.
  - - - Also 1000BaseT and 10GBBaseT
    - - F-Type connectors are used with coaxial cable.
      - BNC are sometimes used but not often
      - Often these use twisted pair cabling (UTP [Unshielded twisted pairs], run about 100m) (STP [Shielded twisted pair], runs about the same but better)
        
        UTP has CAT ratings which is what is used in Ethernet
        
        CAT5 (100Mbps)
        
        CAT6 (1Gbps up to 100m, or 10Gbps up to 55m)
        
        CAT5e (1Gbps)
        
        CAT6a (10Gbps at 100m)
        
        Manufacturer makes up own ratings which ties to known cat ratings. e.g. CAT6e+
    - - Fast and uses light instead of electricity.
        
        Cabling is made out of Kevlar and cladding for reflection, with tiny fibreglass collections to propagate a light signal.
        
        Can use multimode which propagates using LEDs or Single mode which uses lasers. Single mode is better for long distances
      - Connectors
    - - PVC (very cheap and easily burnable)
      - Plenum is resistant to fire but expensive
      - Riser is slightly less resistant than plenum but cheaper (good middle ground)
  - - - The wires inside the cable need to be in a specific order to crimp properly.
        
        Orders
        
        TIA 568A Standard
        
        Order is (Starting from far right at position 8) Brown, Brown-white, Yellow, Blue-white, Blue, Yellow-white, Green, Green-white.
        
        TIA 568B Standard
        
        Order is (Starting from far right at position 8) Brown, Brown-white, Green, Blue-white, Blue, Green-white, Yellow, Yellow-white.
        
        Distance between last twist and crimp is exactly half an inch.
    - - Straight through (Same order on both ends.)
      - Crossover cable (TIA568A to TIA568B) reverse order.
  - - - MDFs usually have Rack setups with distances known as a "u"
        
        The rack has horizontal runs, each of the horizontal runs is a cable that is run from the back of a switch in the rack to a wall panel in the house. The panel on a rack that connects all Ethernet wall outlets to a switch in the house are known as Patch Panels.
        
        Horizontal runs are supposed to be no longer than 90m
        
        Path cables are run from the wall outlets and patch panel into switches and devices.
      - To connect cables from the back of the patch panel to wall outlets a 110 punchdown tool needs to be used.
      - Patch panel punchdown patterns change by manufacturer
      - Testing
        
        Use fox and hound to find stray cables and locate their other end in the patch panel
        
        TDR detects how long a cable is. If there's a 40m run and it gives a different length on the TDR there might be a break.
  - - - Everything is IEEE 802.11 standard.
      - WAP (Wireless Access Point)
      - Infrastructure mode of 802.11 is the most common. WAP is the cornerstone of infrastructure mode. a WAP also needs a WNC / NIC (Wireless network card).
      - Laptop NIC is located in the monitor. Every mobile device has a NIC which is built into the case in modern mobile devices.
      - SSID (Service set identifier) for network identification.
      - Rarer mode (Ad hoc mode)
        
        No WAP just NICs that setup a specific NIC as a WAP for other devices to use. Hot spotting is an example of this.
      - Antennas
        
        Omnidirectional
        
        Radiation pattern looks like a fuzzy ball. Imagine a signal reader orbit around the antenna.
        
        A dipole antenna is the most used of these. The two fuzzy balls on the dipole antenna create a large flat signal pattern.
        
        Highly directional
        
        Propagation looks like a stretched American football. Great for long distance signals in a specific direction.
        
        Patch
        
        A patch antenna is a big fuzzy half ball. Great for propagation in one direction and not another.
        
        Parabolic
        
        Also highly directional and used for extremely long throws.
    - - Original 802.11 was 1Mbps, not seen though
      - 802.11a
        
        54Mbps and uses 5Ghz
      - 802.11b
        
        11Mbps and ran on 2.4Ghz
      - 802.11 based on ISM bands (Industrial, scientific and medical bands). Uses the 2.4 and 5Ghz bands. These bands need to be used to avoid interference. 2.4 runs from 2.412 to 2.484Ghz.
      - Channels were created for each. the 2.4Ghz band has 14 different channels. 14 for Japan. In Europe there is 13 and In the US there's 11.
      - 5Ghz runs from 5.150 to 5.875Ghz, many more channels. A lot of these channel numbers are skipped. It goes from 36-64, then from 100-144 and lastly from 149 to 165.
      - 802.11g
        
        54Mbps and ran on 2.4Ghz, as a result is backward compatible with 802.11b
      - 802.11n (Wifi 4)
        
        100Mbps and ran on both 2.4 and 5Ghz, meaning backward compatible with everything. Introduced MIMO
        
        MIMO (multiple in / multiple out) allows a single WAP to use multiple antennas to change radiation signals to zero in on devices that don't move.
      - 802.11ac (Wifi 5)
        
        Very fast and backward compatible. Introduced multi-user MIMO. Also 802.11ac has a 2.4Ghz radio in there purely for backward compatibility.
    - - SOHO routers work straight away, this is bad for security.
      - Run a site survey to establish what networks are running in the area. Use app like Wifiman
        
        General rule is to set frequency to 1, 6 or 11. But as a more general rule set the wifi to a channel that doesn't overlap with others.
      - 5Ghz channels can be set to automatic most of the time because of the size of their range.
      - Set an SSID but disabling broadcast is common. Almost useless as a security feature.
      - Set lowest compatible mode for higher throughput.
      - If the radio isn't enabled these changes cannot be seen.
      - Connecting
        
        Make sure NIC isn't disabled in Network connections.
        
        Always connect to 5Ghz if possible.
        
        Connecting to a network creates a profile on the device. You can see these in network settings by clicking manage known networks.
        
        If connection errors arise the first step is to forget the network profile.
        
        On many devices the NIC is configured as a DHCP client. This means for an incorrect password you may obtain an APIPA address.
        
        Can statically set a wireless NIC IP. Although this is weird.
      - Wireless Mesh Network (WMN)
        
        Config of WAP takes some technical skill, an alternative is a WMN. This is basically Ad hoc on steroids.
        
        One WMN base station, Place smaller stations throughout house or office. Most cases of this have an app that manages the mesh.
        
        They use third party encryption, not much to setup except a password.
        
        Don't have WAP type throughput, but they can support basic home needs.
      - Other types of wireless connection
        
        RFID (Radio Frequency Identification)
        
        Often a radio sticker that stores a small amount of information. Scanner gives sticker small amount of power so that it can project information in signal.
        
        NFC (Near Field Communication) is RFID
        
        NFC is used for tap-to-pay, tap-to-print etc.
        
        Bluetooth
        
        Looks a lot like 802.11 from signal standpoint.
        
        Designed to connect no more than two devices in a short proximity. This is called a PAN (Personal Area Network)
        
        Classes
        
        Class 1
        
        Power = 100mW, Range = 100m
        
        Class 2
        
        Power = 2.5mW, Range = 10m
        
        Class 3
        
        Power = 1mW, Range = 1m
        
        Pairing
        
        One device in Discovery and another in Search mode. Once two devices find each other they used to go through a 4 digit pin sequence. Newer devices don't use the pin sequence.
    - - Should always have a wifi analyser for troubleshooting WIFI
      - No connectivity
        
        SSID doesn't exist to devices. Could have changed SSID or password.
        
        Could also have a low RF signal, Get closer to the box or antennas to make sure they are working properly.
        
        Could also mean someone turned off the SSID broadcast. To get onto an SSID without broadcast, you need to know the SSID, the security and encryption standards and password. From there you need to make a manual SSID profile.
      - Limited connectivity
        
        Means slow transfer speeds, often times signifies an interference on the network.
        
        Low RF signal can also be a cause of this.
      - Intermittent connectivity
        
        Low RF signal is the cause of this as well.
        
        Too many people on the network, in this case you need more WAPs or QoS or both.
  - - - A number of large providers that together span an entire landmass work together to provide coverage. To do this they need peering agreements to share information. This is done at scattered centres across the landmass known as NOCs (Network Operation Centres) These are known as tier 1 internet services.
      - Tier 2
        
        Entities that aren't quite as big but have decent coverage. Tier 2s don't have peering agreements and they have to pay for their internet. Only for basic internet coverage. Everything else is peered.
      - Tier 3
        
        Tier 3 are the ISPs, they aren't interconnected and they sell their services to customers.
    - - Term for both POTS (Plain Old Telephone Service) and PSTN (Public Switched Telephone Network). Old school telephone connections. Provides a solution for taking analogue voice and sending digital data.
      - Dial up Modem has RJ-11 connectors and a DB-25 serial connector. You can plug this into the back of a computer and this establishes a Comport.
      - Dial up needs a phone number to make a connection. You can connect to the internet using a dial up modem on windows even now.
      - This started the internet but maxed out at 56Kbps.
      - ISDN (Integrated Service Digital) Is a dial up connection, this was a completely digital line that ran at 64 or 128Kbps. Faster than original dial up and entirely digital.
        
        US has an entire ISDN industry.
    - - DSL (Digital Subscriber Line). Earlier version of broadband, piggy backed off phone lines. Came in ADSL (Asymmetric DSL) and SDLS (Symmetric DSL). Upload went from 768Kbps to 3Mbps and Download from 1.5 to 7+Mbps
        
        DSL uses PPoE (Point to Point Protocol over Ethernet). Can put multiple users on a single internet connection.
      - Cable, incoming F-Type connection for internet. Uses DOCSIS (Data Over Cable Service Interface Specification)
        
        Cable speeds are upload/download between 1.5/10Mbps in the old days but today its 50/100Mbps or better.
      - Satellite
        
        Speeds are 3/25Mbps and upwards
        
        Trouble is that satellite has high latency.
      - 802.11 ISP setup
        
        A big proprietary antenna focused on a broadband tower.
    - - All servers have firewalls, often time they can use stateful firewalls that monitor for bad behaviour.
      - FTP (File Transfer Protocol)
        
        Every web browser in the world is an ftp client. Robust ftp though needs a specialized ftp client like FileZilla.
        
        FTP can use Active Mode which kicks ftp into using port 20 for return traffic. Routers often don't like this and block it most of the time It is much faster than passive mode however.
        
        A router supports port triggering to get around this problem. We can tell the router that is somebody sends something out on port 21, allow returns on port 20.
    - - Originally a web based client was used but nowadays browser email is most common.
      - Email protocols, SMTP (Simple Mail Transfer Protocol)-port 25, POP (Post Office Protocol)-port 110, IMAP (Internet Message Access Protocol)-Port 143
        
        Either POP3 or IMAP are used with SMTP not both. POP3 operates by taking your email down to the email client, setting up folders on the client itself. IMAP copies all folders onto the client.
        
        Most common these days are POP3 and IMAP4
      - Most mail these days are secured mail on ports like 587. the SMTP ports 25 etc are almost never used.
    - - Essentially these are intermediary servers that a packet must travel to before going through to the internet.
      - Can use them for enforcing different constraints on clients.
      - Proxy servers can cache so that common websites are easy to get to
    - - A VPN Client will make a direct connection between itself and the WAN side router on the local network.
      - VPN routers have different protocols such as PPTP, IPsec and L2TP
      - When a VPN connection is made it registers as a new network card on windows.
      - Split tunnelling for internet connectivity and VPN access
    - - Internet connected devices that aren't commonplace. Lightbulbs etc. 802.11 is the common way to talk to IOT devices ZigBee can also be used.
      - Z-Wave run in 900Mhz band and is used for IOT devices.
      - Requires a hub and can be used with voice capabilities.
- - - - Webcam (Output)
      - Game controller (input)
      - Hard drive
      - Headset
        
        Microphone (Input)
        
        Headphones (Output)
    - - USB A (Gen 1, 2 and 3)
      - RJ-45 (Network cable connections)
      - Sound connectors (mic and speakers)
      - Fibre optic connector for advanced sound systems
      - Video connections
        
        DVI
        
        HDMI
        
        DisplayPort
      - Power connection
      - Older connections
        
        mini-DIN [PS/2] (Keyboard and mouse)
        
        Parallel Port [LPT] Printers
        
        Serial (Network)
        
        Video Graphics Array [VGA] (Video)
        
        Analog Style [SVideo] (Video)
      - Mobile connections
        
        Anti Theft
        
        Mini DisplayPort
        
        USB-C
        
        Power connector
        
        Disc Drive [Optical Media]
    - - Power supply
        
        Power connectors
      - Video Card
      - Fans
      - Motherboard
      - RAM
      - Storage
        
        SSD
        
        HDD
      - CPU
      - Chipset
        
        Defines motherboard functionality and connection details
      - What do these all mean?
        
        A computer is essentially a very complex math machine (Turing machine) That uses stored data to implement and execute programs to display obtain and communicate information.
        
        On boot a program (Often OS) is loaded from SSD to RAM to run / Also stored from RAM to SSD when closed
        
        A computer is made up primarily of a CPU, RAM and Storage as well as an OS.
        
        Computers are not only desktops, but laptops, Webcams, raspberry pi, Routers and even dishwashers.
  - - - In modern CPUs registers can be in the hundreds with each being around 128 bits long.
    - - Using the machine language we can specify instructions in the following order. Define binary ordering for all registers, press the clock, wait until CPU is complete and repeat these steps.
      - The binary ordering is presented on the external data bus for both calculation and presentation of programs.
      - Comprises in modern CPUs of 4 "men" known as the prefetch, Math, Number and Cache guy. Doing it this way is a great way to utilize pipelining, each pipeline is a segment of a single core inside a potentially multicore CPU. Each of the "men" in this case can be considered a bus or register.
    - - Determined by a system crystal on the motherboard. Essentially it is a quartz clock, this should match the speed of the CPU.
      - Most motherboards run around 200MHz at the high end, maximum cap is about 400MHz.
      - Clock Multiplying
        
        A base BUS speed on the motherboard is multiplied by a variable multiplier that utilizes higher CPU clock speeds. Multiplier varies based on temperature.
      - CPUID CPU-Z (Program for CPU specification of speed)
      - Overclocking
        
        Motherboard communicates with the CPU to utilize high speeds often at the sacrifice of temperature management. Usually makes systems unstable but more powerful.
    - - Hyper-Threading
        
        Essentially each "man" in the pipeline handles multiple different tasks, eg. A smart pipeline which ends up looking more like multiple pipelines in a single core. Hyper threading is a single pipeline that can handle 2 programs at the one time.
      - A CPU has multiple pipelines, each pipeline being a single core.
      - Modern Systems can have up to 24 cores in a CPU.
    - - SRAM (Contained in CPU)
      - Small and extremely fast partition of memory on the CPU for common commands and code.
      - Common CPUs have 3 different Caches
        
        Level 1 Cache
        
        64KB of RAM that is extremely fast (Same speed as multiplied CPU)
        
        Level 2 Cache
        
        128 - 256KB feeder cache. Runs at about half the speed of a the multiplied CPU.
        
        L3 Cache
        
        In MB range but runs at the base CPU speed. Slower than the other two but still much faster than regular RAM.
      - Caches are found on each core.
      - Set association.
        
        A number of blocks in cache memory are divided into sets. Instructions in the main memory are broken into addresses with a block offset, set number and tag. These are used to associate instructions in main memory with a set, reducing the number of comparisons per cache search.
    - - Each CPU has a form factor design
      - Different CPUs commonly has a different microarchitecture. Even if they have a similar or identical form factor.
      - Each CPU producer will often pick a specific microarchitecture and give it a family name eg. Kaby Lake for intel. It will then make as broad range of CPUs with different capabilities all utilizing the same microarchitecture.
      - A Socket is where the CPU connects to the motherboard.
      - Socket names
        
        PGA (Pin Grid Array)
        
        LGA (Land Grid Array)
      - Intel vs AMD
        
        AMD has an AM4 (Mainstream) Socket which is a PGA, and the TR4 (High end) which is also a PGA
        
        Intel has LGA 1151 (Mainstream) and LGA 2066 (High end). These are both land grid array sockets.
  - - - Synchronized to the system crystal. Contains two notches. Utilizes 1678 pin connector.
      - DDR SDRAM (Double Data Rate)
        
        Gives two bits of information per clock cycle. Uses 184 pin connector with single notch.
        
        Clock speed 2 is DDR speed and DDR speed 8 is the PC-Speed rating.
    - - DDR2
        
        Uses 240 pin connector with single notch.
        
        Clock speed of system crystal is multiplied by 4 for the DDR2 speed rating rating, and once again the PC rating is then found by multiplying that by 8. for DDR2 the PC rating is PC2.
      - DDR3
        
        Also uses the 240 pin connector with the notch offset as compared to DDR2. DDR3 speed is computed by multiplying system crystal speed by 2^3 or 8. PC3 is found by multiplying that by 8.
      - DDR4
        
        288 pin stick with another large offset for the notch. Very fast compared to the others. Uses DDR4 speed rating and PC4, both multiply the same as the DDR3 by 8.
    - - Based on a square. Memory sizes are based on a times 4 multiplier. But if using a double sided stick the size of the stick is only doubled.
      - Channels
        
        Motherboards usually have between 2 and 4 slots. But for large server systems this can go up to 16. Extra slots are useful because we can have sticks with smaller form factors adding up to a higher total memory count.
        
        If the mother board supports dual channel, we can use both sticks at once in parallel. Most modern motherboards use dual channel. These are necessary for using the motherboards full capacity.
        
        A single channel needs two identical RAM sticks, each channel can contain different types of RAM often different sizes, but commonly not different speeds or types.
    - - Parity / ECC
        
        RAM commonly has 8 chips per stick that relate to a bit each, often however RAM will be error correcting which will result in an extra chip that handles what's known as a parity bit. A demonstration of why these are useful can be found when researching Hamming codes.
        
        Parity is memory that supports an error in at most 1 message bit. ECC can support at most two error bits in the message portion. Parity is outdated and ECC is now most often used. However very expensive and must be supported by motherboard which is not so common.
      - SO-DIMM
        
        DDR4
        
        260 pin connector
        
        DDR3
        
        204 pin connector
        
        Lower gen SO-DIMM memory has non-uniform characteristics.
        
        Basically just RAM with a smaller physical size
      - SPD Chip
        
        Contains characteristics of a given RAM Stick. can be queried to learn about RAM Stick.
        
        Can be queried using CPUID CPU-Z program or potentially others.
  - - - Essentially the BIOS is firmware that acts as an intermediary between the OS and the hardware.
      - Motherboard contains a BIOS chip
      - M BIOS
        
        Stands for main BIOS, Exists as the primary BIOS chip
      - B BIOS
        
        Backup BIOS in case the M BIOS fails.
      - BIOS contains testing software to make sure system functions before booting into the OS, this software is known as POST firmware. It also contains system setup information in the CMOS.
    - - First thing the motherboard does when the CPU spins up.
      - Runs checks on the system to make sure all the hardware is running correctly.
      - Small speaker exists on modern motherboards to report on POST tests. This is mostly used for Beep codes which are the communication of an issue in the event of a video output failure.
      - Also Display codes exist for other more detailed issues.
      - POST Card
        
        Hexadecimal output that reports error codes. They can be referenced in the motherboard book.
    - - When the BIOS is updated the update is stored in the CMOS chip in older machines.
      - In newer systems there are Single Flash ROM chips. You can flash (reprogram) this chip to upgrade built in BIOS using this chip.
      - To keep time on each system there used to be an RTC (Real time clock) chip, this is not a chip anymore but still exists to synchronize the times on all devices.
      - There exists a CMOS Battery to keep the RTC chip running while the system is turned off.
        
        If these are not there the system will lose its time.
        
        If battery dies, the system update information in the BIOS is removed and have to be reset.
      - CMOS Battery is often a CR2032
    - - Essentially the UEFI is the system setup menu found when you press the boot menu key on a computer.
      - Often user and admin passwords can be set in the UEFI BIOS to prevent unauthorized users from even booting the OS.
      - Replaces traditional 16-bit BIOS in modern systems.
      - System setup enables custom info about changeable devices in scope.
      - Enables changes to CPU speed RAM timings, Passwords, boot options, etc.
    - - Firmware is often extremely safe. But sometimes needs fixing.
      - Often BIOS issues involve a run down or empty CMOS Battery.
      - Flashing can result in issues.
        
        Do not run out of electricity in the middle of a flash.
        
        Make sure it is good power.
        
        Maintain a new copy of the entire BIOS update.
  - - - I/O area is often the same size and this is so that they fit in most cases.
      - Types
        
        ATX (Biggest common form factors) 12 inch by 9.6 inch
        
        MicroATX (Trimmed ATX) 9.6 by 9.6 inches
        
        Mini-ITX (Smallest form factor for small systems)
        
        ITX (Larger version of Mini-ITX / Not commonly seen)
      - Power supply offers standardized connectors
      - All motherboards come with an I/O shield
    - - A chipset is a super smart chip that handles a number of different jobs
      - Chips
        
        Northbridge
        
        Interface to CPU (Memory controller and expansion busses)
        
        Southbridge
        
        Interface to slower stuff (Often I/O)
        
        Todays chipsets are mostly southbridge functionality. CPU handles all northbridge functions
      - A chipset defines what specs a system needs and what is compatible with it. RAM capacity, USB capabilities, etc.
    - - Power connectors
      - SATA ports
      - Capacitors
        
        Voltage regulator modules
        
        Both manage variable power situations
      - I/O Area
      - Expansion slots
        
        PCIe
        
        16 Lane PCIe Connector (GPU port)
        
        Essentially single lane serial data transfer port. Sophisticated in modern motherboards, and is used for speed. Parallel vs Serial discovery led to this technology.
        
        Single lane PCI socket for smaller technologies (Hard Drives etc.)
        
        4 Lane PCIe Connector
        
        USB male expansions
        
        High end serial port and VGA dongle connectors etc.
        
        Mass storage
      - RGB Connectors
    - - USB connectors
      - On/Off switch
      - Audio connectors
      - Inside
        
        Standouts
        
        Pass throughs
        
        Hard drive mounts
        
        Front connectors
        
        Fan connectors (3 or 4 pin connectors)
  - - - Molex (Oldest of the power connectors / Usually for external drives)
      - Mini-connector (Provides power to older hardware like floppy drives but sometimes can be found in modern systems.
      - SATA power (For hard drives and things)
      - PCIe Connector (For video card power)
    - - Good for modular support of different connectors
      - Much more convenient, but can potentially lose wattage efficiency. compared to soldered PSUs
    - - SpeedFan. Application for managing speed of fans inside the OS.
      - Can also be controlled natively through firmware.
    - - Ways they die
        
        Fast
        
        Smoke / Burning smell, fried system. No recovery.
        
        Slow
        
        Capacitors begin to fail. Must be tested with a PSU tester.
        
        Can also plug into motherboard and measure using multimeter.
        
        Usually can be spotted by observing a slow drop in voltage.
    - - Troubleshooting
        
        If you can get BIOS it means CPU, RAM and GPU are working properly. CPU fault is most sinister boot issue.
        
        Often times RAM issues are just incorrect input of sticks.
        
        If video isn't working the CPU may not have built in graphics.
        
        Often times troubleshooting 101 is just to start the setup over again.
        
        Firmware issues can be fixed using a clear CMOS jumper. Resets the BIOS firmware to factory.
        
        Loud noises are often cables stuck in fans, not a whole heap of moving parts internally. Potentially in the power supply but not as often. This will most likely be a blown capacitor.
        
        If RAM problems arise, you can use active recovery or firmware to do recon on the issue.
- - - - Type 1
        
        Bare metal -> Hypervisor -> VM
        
        ESXI, Microsoft Hyper-V, KVM
      - Type 2
        
        Bare metal -> OS -> Hypervisor -> VM
      - once a VM is turned off the whole machine turn into a file.
        
        This means that in server settings we have security, cost savings and power savings. Recovery also. VMs are very powerful.
        
        Gives possibility of entirely virtual networks
  - - - VirtualBox comes with extensions packs. These extension packs allow for features such as dynamic resizing etc.
      - Can create new devices and drives using a virtual machine.
        
        In network settings you can add a bridged network adapter. This essentially installs a virtual network card that can use the same network as the physical computer.
        
        Can also use network settings to add NAT to a VM. This makes a kind of virtual router, it treats the physical computer as the ISP. You can also make a NAT network so that a number of machines exist all on the same network.
  - - - Doing this establishes "rapid elasticity"
      - Also means that you can clone machines on demand and remove afterward. good for seasonal cost and savings.
      - Resource pooling, they can now share electrical and cooling needs as well as storage etc.
    - - Private Cloud
        
        Generate VMs and networks for a single organization.
      - Public Cloud
        
        AWS or Azure are examples of this. Customer focused
      - Hybrid Cloud
        
        Public/Private Cloud
      - Community Cloud
        
        Teams of businesses as a community paying for a cloud together.
    - - Storage and Synchronization, these are things like Google drive, drop box, etc.
      - Email is now cloudified
      - Can also cloudify domain controllers
      - Offsite virtual desktops
      - Streaming
- - - - Identify problem
      - Establish theory of probable cause
      - Test theory to determine cause
      - Establish plan of action to resolve the problem and implement this solution
      - Verify full system functionality, and implement preventative measures
      - Document, finding, action and outcome
- - - - Cornerstone of laser printer is a toner cartridge with a photosensitive drum.
      - The laser imaging process begins with processing.
        
        The job is loaded into printer memory
        
        After which a single spot on the drum is charged using the primary corona with a -400V to -600V charge.
        
        As the drum begins to spin a laser will start to write the job to the drum
        
        Developing begins and the toner starts at around -300V. At this point the toner cartridge will release toner onto the drum where the laser has produced charge.
        
        The transfer corona under the drum gives the paper a charge of around 150V so that the toner will transfer. At which point the toner is attracted to the paper. After which the toner needs to be sealed.
        
        The next process is a fuser assembly that heats and pressurizes the toner onto the paper, the paper is the destaticified, cleaned and given out.
        
        Colour printers use the same process except they have CMYK. Difference is that the 4 toner hoppers for each different toner, they add the toner to an assembly belt which is then used to give the toner to the paper.
      - Printers need cleaning (Often to get into specific spots an anti static vacuum is needed). A maintenance kit is also useful for a printer.
      - Can also have calibration issues, but most printers have a calibration option to fix this.
    - - Inexpensive compared to laser printers (not always the case)
      - How they work.
        
        A number of ink cartridges are connected to a hose with a jet at the other end.
        
        The jet is boiled which sends the ink firing out of the eye with a charge. A number of small metal plates can be used to point the ink in a direction when printing.
        
        This entire contraption is setup on a print head which can be moved left to right on the carriage.
        
        All the colours are CMYK same as laser.
      - Can also be a multifunction device. Often printer, scanner, copier and fax together.
      - Every inkjet has maintenance tools and systems. Often needs to prevent clogging in the jet using blocking and heating. Calibration is also important. Paper jams are also an issue for just about any printer.
    - - Oldest type of printer (Pre-dates PCs)
      - How it works
        
        The printer has ink ribbons that contain pins that come into contact with the paper. All operating on a carriage
        
        Only used tractor feed paper
      - Not really seen anymore, except for in industrial environments
      - Not a lot of maintenance tools for these, they just need cleaning really
    - - Consists of feed mechanism and heating element, heating element often needs cleaning.
      - Special thermal paper can be used in a thermal printer for multiple copies
      - Often used for POS (Point of Sale) situations
      - Need a lot of paper replacements
      - Generate a lot of paper debris, needs to be removed often.
    - - Locally
        
        Can be connected to a local system using USB, Serial (Especially for Thermal Printers).
        
        Read manual and make sure printer is ready to go.
        
        Plug in an make sure it works in device manager. If it doesn't the drivers need to be found and firmware may need to be updated.
        
        Spooler is a set of software that keeps track of print jobs, these can be determined to be working by looking for the printers print queue in device manager.
        
        Can determine whether the printer is setup right using the printer properties in the queue option.
        
        Collate and Duplex are two important features for higher end printers.
        
        Spooler needs permissions to handle cancelling, pausing, etc.
      - Network
        
        Shared
        
        After setting it up locally, Go to printer properties, click on sharing and share printer.
        
        Can setup so that your device is working as the print server. May also need additional drivers for different devices. Similar access requirements for domain usage.
        
        Sharing printers can produce data privacy leaks
        
        Cloud
        
        Wireless printing devices need a Wireless NIC
        
        Protocols for Printing devices network awareness are SLP for Mac and LLDP for Windows. Printers will get their own IP and broadcast automatically.
        
        Can configure TCP/IP settings on printers.
        
        Often times Wireless printers have network setup software that can be downloaded online for the systems that need to get to the printer.
        
        Wireless printers are subject to same 802.11 constraints as other devices.
        
        Can setup Wireless printer to adhoc networks
        
        Bluetooth capable printers do exists but are rare, they are subject to same bluetooth processes as other bluetooth devices.
        
        Some printers have WPS
        
        Zeroconf (Windows) and Bonjour (Mac) are designed to make printing easier. Airprint can also be used on Mac to make the process easier aswell.
        
        Could specific printing
        
        New printers can scan and copy to fax, onenote etc.
        
        Can configure cloud printing with wireless printer. The printer must also have google cloud print capabilities.
  - - - No rights to installation
    - - Physical connection or DHCP issue. Often a network problem.
    - - Wrong or no permissions
    - - No image on display
        
        Sleep mode or turned off, maybe bad display
      - Paper trouble
        
        Something wrong with pickup rollers or separation pads
      - Low memory errors
        
        All printers use RAM, older printers may have trouble with sizes of documents
      - Error codes
        
        Can be a challenge. May need to research the specific error code.
    - - bad drivers
    - - Laser printer problem, foreign matter on roller
    - - Driver or lost colour cartridge
    - - Physical problem
    - - Inkjet problem, related to clogging in the jet
    - - Remove residual toner on the drum
- - - - Tracks
      - 5.25 inch width standard
    - - Sector
        
        Stores certain amount of data (usually 4096)
      - 3.5 inch width standard
      - Made up of platters that have data stored in them, a little arm reads and writes to the platter.
    - - Pages
      - 2.5 inch standard / Also m.2 exists (Laptops)
      - NVMe are a faster alternative to SATA usually used in m.2
      - Modern motherboards are starting to have m.2 connectors for faster SSDs.
    - - LBA is a combination of hardware software that allocates blocks of memory for files. Also means that mass storage devices don't need device drivers in the operating system, which is important.
        
        LBA
        
        Language spoken by LBA is ATA (Advanced Technology Attachment protocol), used to be PATA but this is long dead. SATA does still exist and stands for Serial ATA. All motherboards have a built in SATA controller that can be utilized to connect mass storage.
        
        Can also use an eSATA cable. This stands for External SATA.
    - - 1000 = Kilo
      - 1000, 1000s = Mega
      - 1000 Megas = Giga
      - 1000 Gigas = Tera
      - 1000 Tera = Peta
      - 1000 Peta = Exa
      - You can also do the same thing but for base 2 numbers which relates to binary combinations, or number of possible instructions.
        
        2^10 = Kibi
        
        2^20 = Mebi
        
        2^30 = Gibi
        
        2^40 = Tebi
        
        2^50 = Pebi
        
        2^60 = Exbi
    - - For Serial Attached SCSI (SAS) devices.
      - Nowadays SCSI is only really used in server systems.
      - iSCSI is SCSI devices connected via ethernet cables.
    - - System setup will define where a system boots an OS from and in what order.
      - Essentially you set the order of each motherboard SATA connection in the system setup and it will go down the list looking for the first OS it can find.
      - UEFI cannot be a first boot choice.
    - - RAID 0 (Striping)
        
        Take a piece of the file being saved and chunk it over as whole bunch of different locations. Upside of this is speed but downside is file safety.
      - RAID 1 (Mirroring)
        
        Save whole file on a drive and copy it on another. Slow save speed but very good for data redundancy.
      - RAID 5 (Striping with parity) Requires 3 drives.
        
        Save in chunks over two drives and compute a parity value set for on the fly error correction when chunks get corrupted. If more than one drive is lost the system doesn't work but if not it provides redundancy and speed.
      - RAID 6
        
        Same as RAID 5 with 4 drives. So the system can lose 2 drives before failing.
      - RAID 10 (Striping Mirrors)
        
        Mirroring each stripe over two drives. Needs 4 drives but provides speed and redundancy. Losing a mirrored pair means losing whole file.
      - RAID 0+1
        
        Same process as raid 10 in the opposite direction. will stripe over two drives and then mirror that across another 2 drives. Needs 4 drives total.
      - Proprietary RAIDs
        
        Different RAID formats from distinguished providers.
      - Hardware RAID
        
        Enabling RAID on the system setup usually provides the option on the next boot to configure the RAID array as necessary.
        
        Can enable Hot spares or swappable drives for when a drive fails. Good for an extra layer of redundancy.
    - - Back up files.
      - Mental reinstall for missing steps.
      - Triple check.
      - RAID
        
        Not found
        
        Never been installed, check that RAID controller is active and drivers are setup properly. Is everything as it should be in the system setup.
        
        Not working
      - Read/Write failures
        
        Common in HDD. Each HDD has a lifespan and at the end of this read/write failures are common. use S.M.A.R.T technologies to troubleshoot.
      - Slow performance
        
        Usually means no RAM or Clock speeds.
      - Loud clicking
        
        No fix for this except replacement. Which is why backups are important.
      - Failure to boot.
        
        Check boot order. WINre can be used to recover from boot failures.
      - Drive not recognized.
        
        Reformat usually fixes this.
      - OS not found
        
        Incorrect boot process.
      - Continuous reboots
        
        Usually an operating system issue.
  - - - TN (Twisted Nematic)
      - IPS (In-plane switching)
      - All of these are used for monitor lighting and RGB.
      - OLED (Organic LED), used for thin monitors and flexible monitors.
      - DLP (Digital Light Processing), tiny mirrors setup in a grid to define a resolution. An RGB wheel spins and reflects colours off of mirrors to reflect coloured light.
      - CCFL (Fluorescent tubes)
    - - NITs (Measure of light)
    - - A measure of the amount of time it takes for LCD to go from black to colour to black again.
    - - A GPU is used to keep track of pixel data for each pixel in the panel.
      - Refresh rate is the speed at which the internal scanner can go through a single cycle.
      - CPU + GPU = APU
      - VGA connectors are analog. for monitors it has to be converted to digital and displayed. DVI is digital which is faster
      - DVI-I white with 4 squared is for both digital and analog signals. DVI-D is digital only.
        
        Single link DVI is for single monitors but dual link DVI was originally used for splitting between two monitors. Nowadays high resolution monitors use Dual link DVI for better performance
      - HDMI (High Definition multimedia interface)
        
        Mini-hdmi also exists for tablets and things.
      - DisplayPort is high definition video only connection.
        
        Also has mini-DisplayPort
    - - Commonly use DLP and LCD
      - Light sources are a big deal
        
        Every projector is sold to a lumen spec. 1000 to 1200 lumens is a good amount for a dark room. Anything above 2500 lumens is good for a well lit room.
      - Throw
        
        The throw is the distance a projector can throw an image which relates to its resolution.
      - Pincushion/Keystone/Skew
        
        Adjustable setting for adjusting various distortions in an image.
      - LED projectors are best because the bulbs are inexpensive
    - - Overheat shutdown
        
        Video card heats up and shuts down. Often means bad fans or bad ventilation to the video card.
      - Dead pixels
        
        Allowed and common problem. Just replace this with the manufacturer.
      - Artifacts
        
        Pictures that were on the screen but shouldn't be anymore. Often a video RAM issue, keep and extra card around for testing. No replacement for this.
      - Incorrect colour patterns
        
        Check cables, look at video RAM if that doesn't work.
      - DIM image
        
        Check brightness, check cables
      - Flickering image
        
        check cables
      - Distorted image
        
        Make sure you're running at native monitor resolution. Adjust geometry otherwise
      - Burn In / Persistence
        
        On old technology burn in would happen which is a constant fixed image on the screen. Usually fixed by replacement of panels.
- - - - Every laptop is different on the inside. Be cautious when dealing with the inside of a laptop.
      - Take pictures of the disassembly process to get a clear picture of its makings.
      - CORE
        
        Battery
        
        Hard Drive
        
        SODIMM RAM
        
        RTC Battery
        
        Mini PCIe Express Slot
        
        Optical drive on bigger laptops
        
        CPU
        
        Motherboard
        
        Card Reader
        
        Wifi Antenna in monitor
      - Always start repair by reviewing the online manufacturer info
      - Display
        
        Laptop monitors are usually sealed systems. The best practice is just to replace the whole monitor when there's a monitor issue.
        
        Often has wireless antenna, multifunction connector, camera cable and a touchscreen connector all connected to the controller.
  - - - Mini-USB, not so common these days.
      - micro-USB
      - Lightning
      - USB-C
      - Thunderbolt
      - Wireless Connections
        
        NFC (Near Field Communication)
        
        Bluetooth
        
        IR (Infrared)
        
        802.11
        
        Cellular
        
        Hotspot
        
        Tethering (Physical Connection)
        
        Airplane. Removes all radio wave functionality.
    - - Android
        
        Androids are built for customization.
        
        Folders can also be made in a slightly different way in android.
        
        Assiociated with google
      - IOS
        
        Built for standard non customizable usability.
        
        Folders are makeable and programs can be put into these
        
        Associated with apple
        
        IOS has permissions for apps same as android. Spotlight search is the only real customizable windows in the phone.
        
        Great for backup. Just logging in with icloud account
    - - Contains Controllers, sensors and headset. Its not the same as AR which is more akin to IG filters etc.
    - - Maintenance
        
        CDMA phones (No sim card)
        
        Need a lot of firmware updates. There are different types of updates such as, Baseband updates, Broadband, Radio firmware updates.
        
        PRL (Preferred Roaming List) is a common issue. If connectivity is slow or scattered the PRL might want to be updated
        
        GSM phones (Come with sim cards)
        
        IMSI (International Mobile Subscriber Identity)
        
        IMEI (International Mobile Equipment Identity)
        
        VPN
        
        Needs to be allowed in settings and a profile must be added.
        
        To do this we need 3 things. Give it a name, setup VPN, server IP.
        
        Android may potentially need antivirus software and firewalls. Host based firewalls are important for Android devices.
      - E-mail
        
        Incoming protocol can either be POP3 or IMAP, outgoing is SMTP
        
        will need to know FQDN of SMTP server
        
        Need username, password and port number
        
        Will need to know FQDN for incoming protocol server, as well as username and password and incoming port number.
        
        Back in 2010 they came up with encrypted versions of POP3 (port 995), IMAP (port 993) and SMTP (port 465 or 587)
        
        SSL and STARTTLS need encrypted ports 90 percent of the time. Old ports are not safe but if the new ports are used you get P2PE (Point to Point encryption)
        
        S/MIME (Secure multipurpose Internet Mail Extensions)
        
        For pictures and files in mail. What this does is encrypt the attachments in an email. Obsolete nowadays because the email can be encrypted.
      - Synchronization
        
        Pre-dates the cloud
        
        Want a set of data to be synched somewhere else for continuous backup.
        
        Types
        
        Sync to desktop.
        
        Sync to cloud
        
        Sync to automobile
        
        Bookmarks, browser synchronization
        
        Can sync location data
        
        Sync E-books
        
        Can sync social media data. Either count on the applications to handle the synchronization. Hootsuite is an external application that propagates social media data
- - - - A single device in the network monitoring Firewalls, malware, etc.