Untitled Flashcards Set

IT Midterm Study Guide (Aligned with Practice Quizzes)

Key Concepts & Definitions:

Logical Operations:

  • AND: Both bits must be 1.

  • OR: At least one bit must be 1.

  • Hexadecimal logic example: F0 AND D7 = D0, A6 OR 83 = A7.

Base Conversions:

  • Binary to Decimal: Multiply each bit by powers of 2.

    • 01101011 (binary) = 107 (decimal).

  • Decimal to Binary: Divide by 2 repeatedly, record remainders.

    • 135 (decimal) = 10000111 (binary).

  • Binary to Hexadecimal: Group bits in 4s.

    • 101110101110010 (binary) = 5D72 (hex).

IP Addressing & MAC Addresses:

  • MAC Address Format: AA:BB:CC:DD:EE:FF (hexadecimal).

  • Invalid if digits exceed hex range (00–FF) or incorrect length.

  • Binary to Dotted Decimal: Convert each 8-bit segment separately.

    • 01111011.11100100.00101110.00010001 = 123.228.46.17.

Subnetting:

  • Subnet mask defines network and host portions.

  • Usable hosts = 2^(host bits) - 2.

  • Example: /27 mask = 255.255.255.224, usable hosts = 30.

Effective Rate & Overhead Calculations:

  • Effective data rate per node:

    • (Link Speed Mbps / Nodes per port).

    • Example: 100 Mbps, 4 ports, 24 nodes → 100 Mbps / 4 nodes = 25 Mbps/node.

  • Overhead percentage:

    • (Overhead bits / Total bits) × 100.

    • Example: (100 overhead / 500 total bits) × 100 = 20%.

Network Layered Model:

  • Physical (Layer 1): Signals and physical connections.

  • Data Link (Layer 2): MAC addressing, frame formatting, error detection.

  • Network (Layer 3): Routing, IP addressing.

  • Transport (Layer 4): Reliability, flow control (TCP).

  • Application (Layer 5): Application-level protocols (HTTP, FTP).

Collision & Broadcast Domains:

  • Collision Domain: Devices that compete for access; switches/routers break collision domains.

  • Broadcast Domain: Devices reachable by broadcasts; routers separate broadcast domains.

Network Devices:

  • Hub: Broadcasts signals; Layer 1.

  • Switch: Forwards frames based on MAC address; Layer 2.

  • Router: Routes packets between networks based on IP address; Layer 3.

Network Mediums & Topologies:

  • Star: Easy troubleshooting (Pro), Single point failure (Con).

  • Bus: Cheap, simple (Pro), Single failure disables entire network (Con).

  • Mesh: Reliable, redundancy (Pro), Expensive, complex (Con).

  • Fiber Optic: High speed, low interference (Pro), High cost, complex installation (Con).

Wireless Networks:

  • Ad hoc: Direct device-to-device connections.

  • Infrastructure: Uses central access point.

  • Security: Encryption (privacy), MAC filtering (device restriction).

Additional Quick Concepts:

  • Bandwidth: High frequency minus low frequency (e.g., 95 MHz high, 80 MHz bandwidth → low frequency 15 MHz).

  • UTP cable max length: 100 meters (total length limit).

  • Serial transmission: One bit at a time.

  • Padding bytes in Ethernet: Only if data is too small to meet minimum frame size.

  • Collision detection (CSMA/CD): Non-standard voltage signals a collision.