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.