Questions and Answers
What is the primary purpose of computer networks?
Which of the following devices is classified as a host device?
What are intermediary devices responsible for in a computer network?
Which of the following is NOT a layer of the TCP/IP model?
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Which type of cable is commonly used to connect devices in a network?
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What is a key characteristic of DSL internet service?
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How does a cable modem function in a broadband network?
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What is the primary function of a router in a network?
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What is a significant advantage of fiber optic cables compared to traditional copper cables?
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Which type of network is characterized by connecting devices over short distances using Bluetooth technology?
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What is the main advantage of using Virtual LANs (VLANs) in a network?
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What type of connection improves download speeds and reduces latency for satellite users?
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Which technology allows smartphones to share internet access with other devices?
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Which device is typically used to connect a home or small office to the Internet?
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What distinguishes a Wide Area Network (WAN) from other types of networks?
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What is the main function of the Transmission Control Protocol (TCP)?
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How does User Datagram Protocol (UDP) differ from TCP?
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What role does the Internet Protocol (IP) play in the TCP/IP model?
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Why might an application choose to use UDP over TCP?
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Which of the following is true about TCP and UDP port numbers?
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What is the purpose of a source port number in TCP communications?
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Which port number is used for standard web traffic?
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What is the role of a router in a network?
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Which protocol is used for secure email transmission?
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What type of device regenerates signals to extend the distance a network can cover?
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Study Notes
Overview of Computer Networks
- Essential for sharing resources and facilitating communication between users.
- Enables various online services such as email, news, and blogs.
Importance of Networking Knowledge
- IT professionals must understand networking concepts to meet customer and user needs.
- Core understanding includes network design and impact of devices on data flow.
Networking Devices
- Host devices (end devices) run applications like web browsers and email clients.
- Intermediary devices facilitate data transfer:
- Switches connect multiple devices.
- Routers forward traffic between networks.
- Wireless routers connect wireless devices, often including a switch.
- Access points extend wireless network coverage.
- Modems connect to the Internet.
Types of Network Connections
- Various connection types: DSL, cable, cellular, satellite.
- The TCP/IP model consists of four layers: Network Access, Internet, Transport, Application.
Wireless Networks and Protocols
- IEEE 802.11 Wireless LAN protocols govern wireless networks.
- RFID and NFC enable proximity communication.
- Zigbee and Z-Wave support smart home technology.
Network Cable Types
- Twisted-pair, fiber-optic, and coaxial cables, varying in construction and data transmission capabilities.
- Knowledge of each type's properties and use cases is essential for network design.
Network Types
- PAN (Personal Area Network): Connects devices like smartphones and tablets via Bluetooth.
- LAN (Local Area Network): Connects devices in a limited area, typically owned by an individual or managed by IT.
- VLAN (Virtual LAN): Segments switch ports for better data forwarding and organization.
- WLAN (Wireless LAN): Similar to LAN but uses wireless signals.
- WMN (Wireless Mesh Network): Utilizes multiple access points to extend coverage.
- MAN (Metropolitan Area Network): Network spanning a city or campus.
- WAN (Wide Area Network): Connects geographically separated networks.
- VPN (Virtual Private Network): Securely connects users to another network over the internet.
Internet Connectivity Evolution
- Transitioned from analog telephone broadband to modern services like DSL, cable, and fiber optics.
- DSL offers continuous internet connection divided into distinct frequencies for voice and data.
- Cable internet utilizes coaxial cables which can carry TV and internet signals simultaneously.
Advanced Connection Technologies
- Fiber optic connections provide high bandwidth for extensive data transmission, commonly used in backbones and large data systems.
- Line of Sight wireless uses radio signals for internet access, limited by distance and signal obstructions.
- Broadband satellite service enables connectivity without traditional cables, but has latency issues for real-time applications.
- Mobile technology allows internet access via smartphones, with tethering and mobile hotspot functionalities available.
TCP/IP Protocol Suite
- Comprises protocols for addressing, routing, and data reliability, organized into four layers.
- Transport layer includes TCP (guaranteed delivery, ordered data) and UDP (faster, no delivery guarantee).
- TCP ensures reliable data transmission via numbered segments and acknowledgment, while UDP emphasizes speed for applications like video calls.
Port Numbering
- TCP and UDP use source and destination port numbers to track application communications.
- Port assignments define specific application traffic, with TCP providing structured communication and UDP allowing faster, less reliable interactions.
Summary of Protocol Differences
- TCP is akin to registered mail, ensuring delivery details are tracked.
- UDP resembles unregistered mail, lacking delivery assurance or tracking.### Networking Basics
- Opening a separate browser window generates a new TCP source port (e.g., port 1555) for each session.
- HTTP traffic uses a well-known TCP destination port of 80, while HTTPS uses port 443 for secure communication.
- TCP and UDP utilize source and destination port numbers to manage application conversations on networks.
Port Numbers
- Well-known port numbers:
- HTTP: Port 80
- HTTPS: Port 443
- SMTP: Port 25
- IMAP: Port 143
- POP3: Port 110
- FTP: Ports 20 and 21
- SFTP: Port 22
- DNS: Port 53
- DHCP: Ports 67 and 68
- RDP: Port 3389
- Source port numbers are dynamically generated for each application instance, allowing multiple simultaneous conversations.
Ethernet and MAC Addresses
- Ethernet devices connect using MAC addresses embedded in network interface cards (NICs).
- Ethernet switches forward data by examining the destination MAC address to determine the correct port for traffic flow.
Routers and IP Addresses
- Routers forward IP packets between different networks, using routing tables to determine the best path.
- Devices communicate using IP addresses both within the same network and across different networks.
Network Interface Cards (NICs)
- NICs facilitate physical network connections and possess unique MAC addresses.
- Today's devices commonly use gigabit Ethernet NICs integrated into motherboards.
Network Devices
- Repeaters regenerate weak signals to extend distance in networks; common in fiber-optic systems.
- Hubs connect multiple devices, flooding all traffic to all ports and are considered legacy devices due to inefficiency.
- Switches microsegment traffic, directing data only to the intended recipient and providing higher bandwidth per device.
Managed vs. Unmanaged Switches
- Managed switches can be configured for complex networking needs (e.g., VLANs).
- Unmanaged switches are simpler, requiring no configuration and mostly suitable for small networks.
Access Points and Routers
- Wireless access points enable connectivity for wireless devices and require multiple units for larger coverage.
- Routers interconnect different networks, functioning also as switches and access points in some cases.
Firewall and Security Measures
- Firewalls control network traffic based on a set of predefined rules, protecting networks from unauthorized access.
- Intrusion Detection Systems (IDS) monitor for malicious activity, whereas Intrusion Prevention Systems (IPS) take active measures to block threats.
- Unified Threat Management (UTM) encompasses features of IDS/IPS and provides additional security services like email filtering and VPN.
Endpoint Management
- Endpoint management servers oversee devices within a network, ensuring compliance with security protocols and updates.
Email Security Protocols
- DMARC ensures proper action against unauthorized emails failing SPF or DKIM checks.
- DKIM provides digital signatures to verify email authenticity.
- SPF designates authorized mail servers sending emails on behalf of a domain, reducing spoofing risk.
Networking Toolkit Essentials
- Important tools for network technicians include a cable crimper, wire strippers, punch-down tools, and cable testers.
- A network cable tester verifies the quality and termination of cables, while a toner probe helps trace cable connections.
General Networking Tools
- Wire cutters are used to snip wires, wire strippers remove insulation, and crimpers attach connectors to cables.### Tools for Networking and Testing
- Punch Down Tool: Utilized for terminating wire into termination blocks.
- Multimeter: Measures AC/DC voltage, electric current, and other electrical characteristics for circuit integrity testing.
- Cable Tester: Checks for wiring shorts, faults, or incorrect pin connections.
- Loopback Adapter: Tests the send and receive functionality of computer ports; specific to the port being tested.
- Tone Generator and Probe: A two-part tool for tracing cables; generator applies a tone to the wire while the probe identifies it by detecting the tone.
- Wi-Fi Analyzer: Mobile tool for auditing and troubleshooting wireless networks; shows available networks, signal strengths, and detects configuration issues.
Capturing Network Traffic
-
Network Tap: Captures cable signals for analysis; can be passive or active.
- Passive TAP: Copies and monitors traffic without altering the signal.
- Active TAP: Regenerates signals primarily for gigabit and some fiber links.
- Switched Port Analyzer (SPAN)/Mirror Port: Monitors traffic directed to or from a specific port on a network switch.
Networking Cables
-
Twisted-Pair Cables: Comprises pairs of wires twisted together to reduce electromagnetic interference (EMI).
- UTP (Unshielded Twisted Pair): Common in Ethernet and telephone systems; does not shield against EMI/RFI.
- STP (Shielded Twisted Pair): Features shielding for environments with higher interference.
-
Coaxial Cable:
- 50 Ohm Coaxial Cable: Standard for data and RF transmission; used in radio transmitters and Ethernet networks.
- Provides better shielding than UTP, but harder to install and troubleshoot.
-
Fiber-Optic Cables: Transmit data using light signals; types include:
- Single-Mode Fiber: Small core, suitable for long-distance communication.
- Multi-Mode Fiber: Larger core, used for shorter distances.
Types of Fiber-Optic Connectors
- ST (Straight Tip): Bayonet-style connector for various applications.
- SC (Square Connector): Push-pull mechanism; used in telecom and datacom.
- LC Simplex (Lucent Connector): Small form factor, ideal for high-density applications.
- LC Duplex: Two fibers for bidirectional communication.
TCP/IP Model and Networking Technologies
- Layers in TCP/IP Model: Includes network access, internet, transport, and application layers, facilitating data transmission.
- Wireless Technologies: WLAN protocols (IEEE 802.11 standards) operate on 2.4GHz and 5GHz frequencies.
- Cellular Generations: Evolved from 1G (analog voice) to 5G (supporting AR/VR).
Networking Hardware Devices
- NICs (Network Interface Cards): Provide connectivity for wired/wireless devices, can be internal or USB connected.
- Repeaters and Hubs: Operate at layer 1, repeat signals.
- Switches and Routers: Operate at layers 2 and 3, forwarding frames and packets based on MAC and IP addresses, respectively.
- Security Devices: Include firewalls, IDS, IPS, and UTMs for protecting network data and equipment.
Cable Standards and Wiring Schemes
- T568A and T568B: Define wiring schemes for twisted pair cables; only the orange and green pairs have reversed positions.
- Building and Testing Cables: Emphasized the importance of consistency in wiring schemes during installations, adhering to either T568A or T568B for terminations.
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Description
This chapter emphasizes the fundamental concepts of computer networks, highlighting their importance in resource sharing and communication. Explore how IT professionals utilize networking principles to deliver essential services like email, online newspapers, and applications. Understanding these principles is crucial for meeting modern customer expectations.
