CompTIA A+ Core 1 220-1101 Course Notes

1.0 - Mobile Devices

1.1 - Laptop Hardware

  • Engineered to precise specifications, making repairs challenging.
  • Some laptops are easier to repair than others, requiring continuous learning.
  • Understanding the repair process is crucial, though details vary among manufacturers.
  • Laptop batteries:
    • Power source when unplugged.
    • Replacement can be simple or require complete disassembly.
    • Lithium-Ion (Li-ion) and Lithium-Ion polymer (LiPo) are common; lack "memory effect."
    • Charging diminishes capacity over time.
    • Different form factors for each laptop, with constantly evolving battery technology.
  • Laptop keyboard:
    • Most-used component, typically easy to replace with a few screws and a ribbon cable.
    • External USB keyboards can be used as a less portable alternative.
  • Laptop keys:
    • Repairs may involve removing or replacing keycaps, a delicate process.
    • Manufacturer's instructions should be consulted to avoid damage.
  • Laptop memory:
    • Small Outline Dual In-line Memory Module (SO-DIMM) used in laptops and mobile devices.
    • Often easy to install and replace.
    • Some laptop memory is soldered to the system board, preventing upgrades and requiring full system board replacement.
  • Laptop storage:
    • Magnetic disk:
      • Traditional spinning drive platters, 2.5" form factor.
    • SSD (Solid-state drive):
      • All memory, no moving parts, silent, fast access time, less latency, 2.5" form factor.
    • M.2:
      • Smaller form factor, no SATA data or power cables, easy installation and replacement.
  • Replacing laptop storage:
    • Internal, accessed via a cover or by opening the entire laptop.
    • Modular, with some drives sliding out with just two screws.
    • M.2 drives are even easier to install, similar to RAM installation with one screw.
  • Migrating from HDD to SSD:
    • An impressive upgrade, making the laptop feel new.
    • Install OS on the SSD, move user documents and required applications, which can be time-consuming.
    • Alternatively, image/clone the HDD, which requires imaging software (sometimes included with the SSD or available as commercial/open-source options).
    • Create an image file one drive at a time or use drive-to-drive imaging.
  • 802.11 wireless and Bluetooth:
    • Wireless network connectivity without wires.
    • 802.11:
      • Local Area Network (LAN), high speed, Internet access.
    • Bluetooth:
      • Personal Area Network (PAN), short range, connects peripherals and other nearby devices.

1.1 - Laptop Hardware (continued)

  • Biometrics:
    • Sign in/unlock with fingerprint reader or face recognition ("something you are").
    • Requires OS configuration and specific hardware.
    • Relatively secure due to unique faces and fingerprints.
  • Near-field communication (NFC):
    • Short-distance networking (4 cm or less) for data transfer or authentication.
    • Common on mobile phones and smartwatches, for payments or authentication without passwords in various settings.

1.2 - Laptop Displays

  • Portable LCD:
    • Liquid crystal display where light shines through liquid crystals.
    • Advantages of lightweight, relatively low power, and cost.
    • Disadvantages of challenging black levels and need for separate backlight (fluorescent, LED), which are difficult to replace.
  • LCD technologies:
    • TN (Twisted Nematic) LCD, the original LCD technology, has fast response times for gaming but poor viewing angles with color shifts.
    • IPS (In Plane Switching) LCD offers excellent color representation but is more expensive than TN.
    • VA (Vertical Alignment) LCD is a compromise between TN and IPS, with good color representation but slower response times than TN.
  • OLED:
    • Organic Light Emitting Diode emits light when receiving electric current.
    • Thinner and lighter, flexible, and requires no backlight.
    • Used in tablets, phones, and smartwatches, providing very accurate color representation but at a higher cost than LCD.
  • Wi-Fi Antennas:
    • Multiple antennas (WiFi main/aux, Bluetooth) that wrap around the laptop screen for better signal.
  • Webcam:
    • Integrated camera and microphone for video capture, usually with specialized drivers and software.
  • Microphone:
    • Built-in to the laptop display, suitable for video calls, but analog or USB microphones are better for non-casual use.
  • Fluorescent vs. LED backlighting:
    • LED-backlit LCD displays:
      • Use LEDs instead of fluorescent lights, either around the edge or behind the screen; common in modern laptops.
    • CCFL (Cold Cathode Fluorescent Lamp):
      • Require higher voltage and power, adding thickness to the display; used in older laptops.
  • Backlight and inverter:
    • LCD displays need a backlight (fluorescent lamp/LED). Some laptops use inverters to turn DC into AC.
    • Verify backlight with a flashlight and replace the LCD inverter or display if needed.
  • Digitizer:
    • Uses a pen-like device (stylus) for input, useful for graphical input on laptop/tablets or hybrid devices.
  • Touchscreen:
    • Merges laptop and tablet input where the digitizer responds to touch, often with an available keyboard for versatile input options.

1.3 - Connecting Mobile Devices

  • Phones and tablets connect in various ways, both wired and wireless, for synchronization, connectivity, backup, and identification.
  • USB (Universal Serial Bus):
    • High-speed wired communication for charging and data transfers.
    • Micro-USB, a smaller connection, now common worldwide.
    • Older devices may use Mini-USB.
    • USB-C, a 24-pin double-sided connector, used for hosts and devices, acts as USB 2.0/3.0/3.1/4 connection, and can transmit DisplayPort, HDMI, and Thunderbolt signals.
  • Lightning:
    • Apple proprietary 8-pin digital signal for iPhones and iPads.
    • Advantages include higher power output and reversible insertion.
  • Serial Interfaces:
    • DB-9 (DE-9), commonly used for RS-232 signals (Recommended Standard 232), a serial communications standard since 1969.
    • Traditionally for modem connections, now used as configuration ports for switches, routers, and firewalls via USB to DB-9 converter cables.
  • NFC (Near Field Communication):
    • Sends small data amounts wirelessly over a limited area, built into phones for payment systems, transportation, and information exchange.
    • Functions as access token or identity card with short range and encryption.
  • Bluetooth:
    • High-speed communication over short distances for Personal Area Networks (PAN).
    • Connects mobile devices like smartphones, tethering, headsets/headphones, health monitors, car and phone integration, smartwatches, and external speakers..
  • Hotspot:
    • Turns a phone into a WiFi hotspot, acting as a personal wireless router.
    • Extends cellular data network, dependent on phone type and provider, may incur extra charges.

1.3 - Mobile Device Accessories

  • Touch pens:
    * Touchscreen pen / touch screen stylus / capacitive stylus: Activate the interface without actually touching it
    * Handwriting: Note taking, signatures
    * Precise selection: Easier to see the screen
  • Active stylus:
    • An advanced writing tool that communicates directly with the device, offering pressure sensitivity and programmable buttons, must be compatible with the tablet (e.g., Apple Pencil with iPad).
  • Drawing pad:
    • Uses active stylus with an external digitizer for precise input.
  • Trackpad:
    • Replaces the mouse, useful in tight areas, common on laptops, external options also available (battery powered, Bluetooth).
    • Supports drag and tap, multiple finger input for right-clicking, zooming, and window control; can be enabled/disabled.
  • Headsets:
    • Offer hands-free audio via earphones and microphone.
    • Wired: USB connections on laptops or 3.5mm TRRS connector (analog audio jack); iPhones use Lightning port.
    • Wireless: Bluetooth headsets.
  • Speakers:
    • Provide mobile audio via battery power and wireless Bluetooth link.
    • Offer stereo sound in a small package.
  • Camera / webcam:
    • Internal (laptops/tablets/phones) or external (desktops), accessible from multimedia applications, photo utilities, and video conferencing for real-time video.
  • Docking station:
    • Allows use of external keyboard and mouse, extends existing laptop interfaces, adds functionality (desktop adapter cards), avoids cable issues.
  • Port replicator:
    • Similar to docking station but lacks expansion card option, usually connects via USB.

1.4 - Cellular Standards

  • Cellular networks:
    • Mobile devices utilize "cell" phones.
    • Land is divided into "cells," each covered by an antenna with specific frequencies.
  • 2G networks:
    • GSM (Global System for Mobile Communications) and CDMA (Code Division Multiple Access) provide poor data support, originally using circuit-switching.
  • GSM (Global System for Mobile Communications):
    • A dominant mobile networking standard (90% of market) originally from the EU with worldwide coverage.
      • Used by AT&T and T-Mobile in the United States
      • Allows SIM card (Subscriber Identity Module) to be moved between phones.
      • Original GSM used multiplexing, allocating time slices to each user.
  • CDMA (Code Division Multiple Access):
    • Allows simultaneous communication using different codes to filter calls on the receiving side.
      • Used by Verizon and Sprint
      • Has handsets controlled by the network provider, limiting adoption elsewhere.

1.4 - Cellular Standards (continued)

  • 3G technology:
    • Introduced in 1998, upgraded data connectivity over 2G, with improvements leading to several megabits per second.
    • Increased bandwidth for GPS, mobile television, video on demand, and conferencing.
  • 4G and LTE:
    • LTE (Long Term Evolution) is a "4G" technology converging GSM and CDMA providers using GSM and EDGE.
      • Standard supports download rates of 150 Mbit/s.
      • LTE Advanced (LTE-A):
        • Standard supports download rates of 300 Mbit/s.
  • 5G:
    • Fifth generation cellular networking launched worldwide in 2020, offering significant performance improvements at higher frequencies.
    • Speeds may range from 100-900 Mbit/s, eventually reaching 10 gigabits per second.
    • Impacts IoT by reducing bandwidth constraints, enabling larger data transfers, faster monitoring, and more cloud processing.
  • Updates:
    • PRL (Preferred Roaming List) updates for CDMA networks (Verizon, Sprint) enable phones to connect to the right tower, updated over the air (OTA).
  • Hotspot:
    • Turns a phone into a WiFi hotspot, acting as a personal wireless router to extend the cellular data network, dependent on phone type/provider.
    • May require additional charges and data costs..
  • Bluetooth pairing: * Use or verify a PIN using built-in security * Pair the devices one time: Future connections should be automatic * The manufacturer may prefer a specific sequence * Discoverable mode isn’t always obvious
    • Connects a Bluetooth device with built-in security using a PIN, pairs devices once for automatic future connections, and may require a specific manufacturer sequence.
  • Bluetooth pairing process:
    • Enables Bluetooth on both devices via settings.
    • Sets devices to discoverable mode, selects the discovered device, enters/confirms the PIN, and then tests the connectivity.
  • GPS: (Global Positioning System) - Created by the U.S. Department of Defense: Over 30 satellites currently in orbit
    *Precise navigation based on timing differences
    *Need to see at least 4 satellites
    Longitude, latitude, altitude
    *Mobile device location services and geotracking: Maps, directions
    *Determine physical location based on GPS, WiFi, and cellular towers
  • MDM (Mobile Device Management):
    • Manages company-owned and user-owned mobile devices (BYOD).
    • Centralized management with specialized functionality.
    • Sets policies on apps, data, camera, etc., and controls the remote device or a partition, managing access via screen locks and PINs.
  • MDM configurations:
    * Corporate email configuration-The user does not need to configure anything. The MDM makes the changes on the device:
    *Account details, server address, communication method
    * Two-factor authentication: Require specific authentication types
    *Biometrics, pseudo-random authentication app
    *Corporate applications Allow or restrict app installation Prevent unauthorized app usage

1.4 - Mobile Device Connectivity

  • Configuring a mobile device:
    * Telephone / Text messaging - Many settings are preconfigured
    *Email: Everyone handles email services differently : Corporate email configurations can vary
    * Data synchronization: Based on data rates and speedsImportant for backup and recovery
  • Microsoft 365-:
    • Outlook, Exchange- Microsoft’s email service: Usually the same for Hotmail and Outlook.com
  • Authenticate to Microsoft 365: Username, password Select the items to synchronize
    *Changes in Outlook will appear on the mobile device Same process for Google Workspace: Formerly known as G Suite
  • iCloud:
    * Select synchronization options: Extensive customization - Provides an iCloud username and password
    *Synchronize to macOS: Use your desktop, laptop, or mobile device Use your desktop, laptop, or mobile device for synchronization
  • Synchronizing data:
    • Data types include mail, pictures, music, video, calendar, contacts, and data caps and transfer costs.
      • Cellular vs 802.11: Enable or disable network connections, control the use of cellular downloads Use your desktop, laptop, or mobile device

2.1 - Introduction to IP

  • TCP and UDP are transported inside IP and encapsulated by the IP protocol as two methods to move data, each with different features.
    Transported inside of IP: Encapsulated by the IP protocol
    Two ways to move data from place to place: Different features for different applications
    OSI Layer 4: The transport layer
  • Multiplexing- Use many different applications at the same time TCP and UDPTCP and UDP
  • TCP - Transmission Control Protocol: CommunicationTCP-Transmission Control Protocol
    • Connection-oriented: A formal connection setup and close
    • “Reliable” delivery:
      • Recovery from errors Can manage out-of-order messages or retransmissions
      • Flow control: The receiver can manage how much data is sent
  • UDP: User Datagram Protocol: CommunicationUDP-User Datagram Protocol
    • Connectionless: No formal open/close to the connection
    • “Unreliable” delivery:
      • No error recovery - No reordering of data or retransmissions
      • No flow control: Sender determines the amount of data transmitted

2.1 - Introduction to IP (continued)

  • Why would anyone ever use UDP?
    • Real-time communication-There’s no way to stop and resend the data - Time doesn’t stop for your network
      Connectionless protocols:
      DHCP (Dynamic Host Configuration Protocol):
      TFTP (Trivial File Transfer Protocol)
      HTTPS (Hypertext Transfer Protocol Secure)
      SSH (Secure Shell)
      The application doesn’t worry about out of order frames or missing data. TCP handles all of the communication overhead.The application has one job
      Speedy delivery:
      *The IP delivery truck delivers from one (IP) address to another (IP) address
      Every house has an address, every computer has an IP address
      Boxes arrive at the house / IP address Where do the boxes go?
      Each box has a room name: Port is written on the outside of the box
      Drop the box into the right room. Lots of ports- IPv4 sockets-Server IP address,protocol,server application port numberClient IP address, protocol,client port number
      Non-ephemeral ports-permanent port numbers-Ports 0 through 1,023
      Usually on a server or service. Ephemeral ports-temporary port numbers-Ports 1,024 through 65,535
      Determined in real-time by the clientTCP and UDP ports can be any number between: 0 and 65,535:
      Most servers (services) use non-ephemeral (not-temporary) port numbers: This isn’t always the case-It’s just a number.
      Port numbers are for communication, not securityService port numbers need to be “well known”. Port numbers are for communication, not securityTCP port numbers aren’t the same as UDP port numbers TCP port numbers aren’t the same as UDP port numbers

2.1 - Common Network Ports

*Port numbers- well-known port number-client and server need to match, important for firewall rules- Port-based security, a bit a rote memorization- Becomes second nature after a while, important to know- Port number, protocol and how the protocol is used
*FTPFile Transfer Protok- tcp/20 (active mode data), tcp/21 (control)- Transfers files between systems: Authenticates with a username and password: Some systems use a generic/anonymous login-Full-featured functionality: List, add, delete, etc.
*SSH- Secure Shell: Encrypted communication link-tcp/22 Looks and acts the same as Telnet:
Telnet- Telecommunication Network-tcp/23-Login to devices remotely- Console access- In-the-clear communication- Not the best choice for production systems:
SMTP - Simple Mail Transfer Protocol: Server to server email transfer-tcp/25: Also used to send mail from a device to a mail server: Commonly configured on mobile devices and email clients: Other protocols are used for clients to receive email-IMAP, POP3
*DNS- Domain Name System: Converts names to IP addresses- udp/53: www.professormesser.com = 162.159.246.164
Typically many DNS servers in production: DHCP- Dynamic Host Configuration Protocol: Automated configuration of IP address, subnet mask and other options- udp/67, udp/68: Requires a DHCP server- Server, appliance, integrated into a SOHO router, etc.. Dynamic/ pooled- IP addresses are assigned in real-time from a pool.
Each system is given a lease and must renew at set intervals. DHCP reservation- Addresses are assigned by MAC address in the DHCP server
Manage addresses from one location

2.1 - Common Network Ports (continued)

  • HTTP and HTTPS:
    • Hypertext Transfer Protocol: Communication in the browser - And by other applications
      *In the clear or encrypted: Supported by nearly all web servers and clients.:
      *POP3 / IMAP
      *Receive emails from an email server: Authenticate and transfer POP3- Post office Protocol version 3- tcp/110- Basic mail transfer functionality. IMAP4- Internet Message Access Protocol v4- tcp/143- Includes email inbox management from multiple clients
  • SMB- Server Message Block: Protocol used by Microsoft Windows-File sharing, printer sharing-Also called CIFS (Common Internet File System). Direct SMB communication over TCP without the NetBIOS transport Direct over tcp/445 (NetBIOS-less)
  • SNMP - Simple Network Management Protocol: Gather statistics from network devices-Queries: udp/161Traps: udp/162 v1- The original Structured tables In-the-clear v2-A good step ahead Data type enhancements Bulk transfers Still in-the-clear v3-A secure standard: Message integrity: Authentication: Encryption
    *LDAP-LDAP (Lightweight Directory Access Protocol) tcp/389
    Store and retrieve information in a network directory
    Commonly used in Microsoft Active Directory: RDP- Remote Desktop Protocol Share a desktop from a remote location-tcp/3389 Remote Desktop Services on many Windows versions: Can connect to an entire desktop or just an application: Clients for Windows, macOS, Linux, Unix, iPhone,Android, and others

2.2 - Network Devices

*Network devices: Many different devices and components: All have different roles
Some of these functions are combined together Wireless router/switch/firewall
Compare different devices: Understand when they should be used: Routers Routes traffic between IP subnets: Makes forwarding decisions based on IP address
Routers inside of switches sometimes called: “layer 3 switches”. Often connects diverse network types: LAN, WAN, copper, fiber
Switches: Bridging done in hardware: Application-specific integrated circuit (ASIC)
Forwards traffic based on data link address Many ports and features: The core of an enterprise network
May provide Power over Ethernet (PoE)
Multilayer switch: Includes routing functionality: Unmanaged switches. Very few configuration optionsPlug and playFixed configuration: No VLANs: Very little integration with other devices: No management protocolsLow price pointSimple is less expensive: Managed switches: VLAN support: Interconnect with other switches via 802.1Q Traffic prioritization: Voice traffic gets a higher priority Redundancy support: Spanning Tree Protocol (STP) Port mirroring: Capture packets.
External management: Simple Network Management Protocol (SNMP): Access pointNot a wireless router. A wireless router is a router and an access point in a single device.
An access point is a bridge. Extends the wired network onto the wireless network:: Makes forwarding decisions based on MAC addressMake forwarding decisions based on MAC address
Patch Panels Combination of punch-down blocks and RJ-45 connectorsRun from desks are made once Permanently punched down to patch panelPatch panel to switch can be easily changed: No special tools Use existing cables
FirewallsFilters traffic by port number-OSI layer 4 (TCP/UDP). Some firewalls can filter based on the application
Can encrypt traffic into/out of the networkProtect your traffic between sites; Can proxy traffic. - A common security technique
Most firewalls can be layer 3 devices (routers)
Usually sits on the ingress/egress of the network: Power over Ethernet (PoE): Power provided on an Ethernet cable One wire for both network and electricity-Phones, cameras, wireless access pointsUseful in difficult-to-power areas: Power provided at the switch-Built-in power-EndspansInline power injectorMidspans Hub “Multi-port repeater” : Traffic going in one port is repeated to every other port: Everything is half-duplexBecomes less efficient as network traffic increases. 10 megabit / 100 megabitDifficult to find today.

2.2 - Network Devices (continued)

*Cable modern broadband-transmission across multiple frequencies-different traffic types, Data on the “cable” network-DOCSIS (Data Over Cable Service Interface Specification), High-speed networking:Speeds up to 1 Gigabit/s are available, Multiple services: Data, voice, video ADSL (Asymmetric Digital Subscriber Line) Uses telephone linesDownload speed is faster than the upload speed (asymmetric)
ONT: Optical network terminal
Fiber to the premises
Connect the ISP fiber network to the copper network
Demarcation point (demarc) in the data center
Terminal box on the side of the building
Line of responsibility One side of the box is the ISP Other side of the box is your network Network Interface Card (NIC)
The fundamental network device Every device on the network has a NIC
Computers, servers, printers, routers, switches,phones, tablets, cameras, etc.
Specific to the network type Ethernet, WAN, wireless, etc.
Often built-in to the motherboard Or added as an expansion card :: Many options Single port, multi-port, copper, fiber

2.2 - Software Defined Networking

  • SDN (Software Defined Networking):
    * Networking devices have different functional planes of operation
    Data, control, and management planes: Split the functions into separate logical units
  • Extend the functionality and management of a single device
    Perfectly built for the cloud
    Infrastructure layer / Data plane: Process the network frames and packets
    Forwarding, trunking, encrypting, NATControl layer / Control plane: Manages the actions of the data plane
    * Routing tables, session tables, NAT tablesDynamic routing protocol updatesExtend the physical architecture
    SDN data flows
    * Application layer / Management plane: Configure and manage the deviceSSH, browser, API

2.3 - Wireless Network Standards

Wireless standards- Wireless networking (802.11)Managed by the IEEE LAN/MAN Standards Committee (IEEE 802)
Many updates over timeCheck with IEEE for the latest: The Wi-Fi trademarkWi-Fi Alliance handles interoperability testing802.11a
One of the original 802.11 wireless standards: October 1999- Operates in the 5 GHz range. Or other frequencies with special licensing54 megabits per second (Mbit/s)Smaller range than 802.11bHigher frequency is absorbed by objects in the way: Not commonly seen today.
802.11b Also an original 802.11 standard- October 1999:: Operates in the 2.4 GHz range 11 megabits per second (Mbit/s): Better range than 802.11a, less absorption problemsMore frequency conflictBaby monitors, cordless phones, microwave ovens, Bluetooth. Not commonly seen today:.802.11g An “upgrade” to 802.11b- June 2003 Operates in the 2.4 GHz range 54 megabits per second (Mbit/s)- Similar to 802.11a Backwards-compatible with 802.11b Same 2.4 GHz frequency conflict problems as 802.11b)802.11n (Wi-Fi 4). The update to 802.11g, 802.11b, and 802.11a- October 2009 Operates at 5 GHz and/or 2.4 GHz 40 MHz channel widths: 600 megabits per second (Mbit/s)- 40 MHz mode and 4 antennas 802.11n uses MIMOMultiple-input multiple-output
Multiple transmit and receive antennas.
802.11ac (Wi-Fi 5): Approved in January 2014 Significant improvements over 802.11n Operates in the 5 GHz bandLess crowded, more frequencies (up to 160 MHz channel bandwidth) Increased channel bonding - Larger bandwidth usage Denser signaling modulation-Faster data transfers Eight MU-MIMO downlink streams: Twice as many streams as 802.11n Nearly 7 gigabits per second
*802.11ax (Wi-Fi 6) Approved in February 2021
The successor to 802.11ac/Wi-Fi 5 Operates at 5 GHz and/or 2.4 GHz:
20, 40, 80, and 160 MHz channel widths 1,201 megabits per second per channel
*A relatively small increase in throughput
Eight bi-directional MU-MIMO streams. Orthogonal frequency-division multiple access (OFDMA)
Works similar to cellular communicationImproves high-density installations

2.3 - Wireless Network Standards (continued)

*Long-range fixed wireless: Wireless access point in a house with the stock antennas You might get a range of 40 to 50 metersTry connecting two buildings located miles from each other - Fixed directional antennas and increased signal strength: Outdoors- Minimal signal absorption or bounce Directional antennas Focused, point-to-point connection Wireless regulations are complexRefer to your country’s regulatory agency Frequency useUnlicensed 2.4 GHz or 5 GHz frequenciesAdditional frequencies may be available Additional licensing may be requiredSignal strength Indoor and outdoor power is usually regulatedOutdoor antenna installation is not trivial: Get an expert, be safe
RFID-Radio frequency identification- It’s everywhere: Access badges: Inventory/Assembly line trackingPet/Animal identification: Anything that needs to be tracked Radar technologyRadio energy transmitted to the tagRF powers the tag, ID is transmitted back :: Bidirectional communicationSome
tag formats can be active/poweredNFC (Near field communication) Two-way wireless communicationBuilds on RFID, which is mostly one-way Payment systemsMajor credit cards, online wallets
Bootstrap for other wireless: NFC helps with Bluetooth pairing: Access token, identity “card”Short range with encryption support

2.3 - Wireless Network Technologies

*802.11 technologiesFrequency- 2.4 GHz or 5 GHz And sometimes both ChannelsGroups of frequencies, numbered by the IEEE. Non-overlapping channels would be idealRegulations: Most countries have regulations to manage frequency useSpectrum use, power output, interference requirements, etc. Bluetooth Remove the wiresHeadsets, speakers, keyboards/miceUse the 2.4 GHz rangeUnlicensed ISM (Industrial, Scientific and Medical) band Same as 802.11.
Short-rangeMost consumer devices operate to about 10 meters :: Industrial Bluetooth devices can communicate over 100 meters

2.4 - Network Services

*Web server Respond to browser requests Using standard web browsing protocols-HTTP/HTTPSPages are built with HTML, HTML5 Web pages are stored on the server Downloaded to the browser Static pages or built dynamically in real-time Authentication serverLogin authentication to resources-Centralized management Almost always an enterprise serviceNot required on a home networkUsually a set of redundant servers Always available Extremely important service SpamUnsolicited messages Email, forums, etc.::Various content-Commercial advertising Non-commercial proselytizing. Phishing attemptsSignificant technology issue- Security concerns, resource utilization, storage costs, managing the spam
Spam gateways Unsolicited emailStop it at the gateway before it reaches the userOn-site or cloud-based, All-in-one security appliance Next-generation firewall, Unified Threat Management (UTM) / Web security gateway, URL filter/Content inspection, Malware inspection Spam filter, CSU/DSU Router, Switch Firewall- IDS/IPS Bandwidth shaper VPN endpoint Load balancers Distribute the load::: Multiple servers Invisible to the end-user Large-scale implementations Web server farms, database farmsFault tolerance, Server outages have no effect Very fast convergence
DNS server Domain Name System Convert names to IP addresses And vice versa. Distributed naming system The load is balanced across many different servers Usually managed by the ISP or IT department A critical resource DHCP server Automatic IP address configuration. Very common service - Available on most home routersEnterprise DHCP will be redundant Usually running on central servers, File server Centralized storage of documents, spreadsheets, videos, pictures, and any other files A fileshare Standard system of file managementSMB- Server Message Block, Apple Filing Protocol (AFP), etcThe front-end hides the protocol Copy, delete, rename, etc. Print serverConnect a printer to the network Provide printing services for all network devicesMay be software in a computer: Computer is connected to the printer May be built-in to the printer:Network adapter and software Uses standard printing protocolsSMB Server Message Block, IPP Internet Printing Protocol, LPD Line Printer Daemon Mail server Store your incoming mail Send your outgoing mailUsually managed by the ISP or the IT department A complex set of requirementsUsually one of the most important services- 24x7 support Syslog Standard for message logging Diverse systems, consolidated log. Usually a central logging receiverIntegrated into the SIEMYou’re going to need a lot of disk spaceNo, more More than that

2.4 - Network Services (continued)

  • Load Balancer:
    • Configurable load: Manage across servers
      TCP offload: Protocol overhead: SSL offload-encryption/decryption
  • Caching:Fast response- Prioritization:Qos:Content switching: Application-centric balancing Proxyserver:An intermediate server The client makes the request to the proxyThe proxy performs the actual request, The proxy provides results back to the client Helpful features- Access control,caching URL filtering, content scanning,:SCADA/ICS Supervisory Control and Data Acquisition System Large-scale, multi-site Industrial Control Systems (ICS) PC manages equipment
  • Power generation, refining, manufacturing equipmentFacilities, industrial, energy, logistics:: Distributed control systems Real-time information. System control Requires extensive segmentation. No access from the outside, Legacy and embedded systems, Legacy Systems. Another expression for: “really old” May also be Very Important” Learning old things can be just as important. asLearning the new
    Embedded systems. Purpose-built device not usual to have direct access to the operating system:
    Alarm system, door security, time card system: Iot (Internet of Things) devices:Refrigerators; Smart Devices Smart speakers respond to voice commands Air control: Thermostats, temperature control: Access - Smart doorbells::May require a segmented network. Limit any security breaches

2.5 - IPv4 and IPv6

*IP address IPv4 is the primary protocol for everything that we do: you probably won’t configure anything else IPv6 is now part of all major operating systems
And the backbone of our Internet infrastructure IPv4 addresses Internet Protocol version 4 Osi Layer 3 address: IPv6 addresses
Internet Protocol v6: 128-bit address
Networking with IPv4 IP Address Subnet mask Default gateway DNS servers-We remember names:: Internet routers don’t know name: Routers only know IP address: Something must to translate between names. and IP addresses Domain Name Services There will must be configure two DNS servers in your IP configuration

2.5 - IPv4 and IPv6 (continued)

  • Turning dynamic into static DHCP assigns an IP address from the first available from a large pool of addressesYour IP address will occasionally change: You may not want your IP address to changeServer, printer, or personal preference Disable DHCP on the device Configure the IP address information manually Requires additional administration: Better Configure an IP reservation on the DHCP server Associate a specific MAC address with an IP addressAvoid manual configurations: No DHCP server reservation: You configure the IP address manually Difficult to change later - You must visit the device again A DHCP reservation is preferable Change the IP address from the DHCP server Automatic Private IP Addressing (APIPA) A link-local address - No forwarding by routers: IETF has reserved 169.254.0.0 through 169.25