Unit 4 Flashcards
Introduction to LANs
Definition: A network consists of connected computing devices (nodes) through a communication channel (transmission medium).
Purpose: Share hardware and software resources.
LAN: Local Area Network for nearby computers, e.g., in an office or home.
LAN Hardware
Key Nodes: PCs, workstations, servers, printers, mobile devices.
Network Interface Cards (NIC): Connects nodes to network media like cables.
Connecting Devices: Switches, repeaters, bridges, routers.
Bounded Connection Media
Cables: Known as bounded media, carry signals between devices.
Examples: Twisted pair and fibre optic cables.
Twisted-Pair Cable
Structure: Two insulated copper wires twisted together.
Types: Unshielded Twisted-Pair (UTP) and Shielded Twisted-Pair (STP).
Unshielded Twisted-Pair (UTP) Cable
Common Use: Most widely used network cable.
Advantages: Easy to install and troubleshoot.
Disadvantages: Limited to 100m, vulnerable to eavesdropping, attenuation, and crosstalk.
Fibre-Optic Cable
Function: Transmits data as pulses of light.
Advantages: High speed, secure, long-distance transmission.
Disadvantages: Expensive, requires expertise for installation.
Unbounded Connection Media
Definition: Wireless connections like infrared, Bluetooth, microwave, and radio waves.
Application: Useful for long-range communication where cables are impractical.
Wireless Technologies
Bluetooth: Short-range, secure, inexpensive, automatic.
Near Field Communication (NFC): Wireless communication within close proximity.
Radio Waves: Used in communication technologies like radio and TV.
Network Topologies
Topology: Physical setup of a network (how devices are connected).
Types: Star, bus, ring, and hybrid topologies.
Star Topology
Structure: Nodes connect to a central switch.
Advantages: Easy setup, isolated faults, easy to extend.
Disadvantages: Requires more cabling, if the switch fails, the network fails.
Ethernet Technology
Purpose: Connects nodes in a LAN, enabling communication via a common protocol.
Function: Governs data transmission and format within the network.
Network Addressing
IP Address: Unique address for devices to communicate on the Internet.
MAC Address: Unique hardware identifier for devices on a network.
Internet Protocols
Role: Define data transmission, error control, compression, and communication procedures between devices.
ARP: Links MAC addresses to IP addresses in a network.
DHCP and IP Addresses
Static IP: Manually configured, doesn’t change. Used for devices like servers or network printers.
Dynamic IP: Can change over time, more secure for regular users.
DHCP Overview:
Purpose: Automates IP addressing.
Function: Device requests an IP address from the DHCP server, which assigns one from its pool.
Tracking: DHCP server keeps track of used and available addresses, ensuring no conflicts.
Reconnection: If a device reconnects, it may not receive the same IP address as before.
DNS
DNS is like the Internet’s phone book.
Function: Translates domain names into IP addresses.
Central Registry: Stores DNS information, regularly updated by ISPs and hosting companies.
TCP/IP Protocol
Role: Communication protocol for the Internet, defines rules for data exchange.
Usage: Web browsing, email, and all internet-based communication.
IP Address: Each computer and domain uses an IP address as part of TCP/IP.
TCP vs UDP
TCP:
Reliability: Connection-oriented; resends lost data, ensuring no corruption.
Order: Delivers messages in the correct order.
Examples: Used in web browsing, email, and file transfers.
UDP (User Datagram Protocol):
Reliability: Connectionless; no guarantee of data delivery, possible corruption.
Order: Messages may arrive out of order.
Examples: Used in streaming media, VoIP, online gaming.
LAN Network Devices - NIC
Network Interface Card (NIC):
Function: Connects the computer to the network cable.
Installation: In older computers, NICs were installed in an expansion slot. Now, it’s built into the motherboard.
Connection: A network cable attaches to the NIC’s port, creating a physical network connection.
LAN Network Devices - NIC
Network Interface Card (NIC):
Function: Connects the computer to the network cable.
Installation: In older computers, NICs were installed in an expansion slot. Now, it’s built into the motherboard.
Connection: A network cable attaches to the NIC’s port, creating a physical network connection.
LAN Network Devices - Repeater
Repeater Overview:
Purpose: Boosts signal strength over long distances.
Function: Strengthens signals without analyzing them.
Limitation: Can’t inspect packets or reduce traffic congestion.
LAN Network Devices - Switch
Purpose: Connects devices in a star topology.
Function: Uses MAC addresses to send data to the correct device, reducing network traffic.
Lookup Table: Stores MAC addresses and forwards frames to the matching device.
LAN Network Devices - Router
Purpose: Connects different networks, determines the best data path using IP addresses.
Function: Uses a routing table to find the most efficient route for data packets.
Capabilities: Can analyze, repackage, and send data over different networks, beyond what a switch, bridge, or repeater can do.
