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Quick Guide to Seven Second Subnetting

Aug 6, 2024

Lecture Notes: Seven Second Subnetting Process

Introduction

  • Previous videos: Subnetting manually using the magic number method.
  • Presenting a faster method for subnetting: the Seven Second Subnetting process.
  • Designed for certification exams to avoid complex math.

Key Concepts

  • Tables Creation: Crucial for quick subnetting reference.
  • Comparison: Magic number method vs. Seven second subnetting method.
  • Customization: Adapt methods to your preference.

Tools for Seven Second Subnetting

  • Chart Preparation: Essential for quick calculations.
  • Digital/Physical Whiteboards: Use them for creating charts during exams.

Example Process

  1. Standard Subnet Mask: 255.255.255.0 (single subnet).
  2. Borrowing Bits: More subnets (e.g., 255.255.255.128 -> 2 subnets).
  3. Host Ranges: Define ranges for each subnet.
  4. Chart Summary: CIDR block notation for octets, network counts, and address per subnet.

Practical Steps

  1. Convert IP and Subnet Mask to Decimal: E.g., 165.245.12.88/24.
    • Decimal Conversion: IP already in decimal, convert subnet mask using chart (e.g., /24 -> 255.255.255.0).
  2. Calculate Network/Subnet Address: Bring down IP based on mask.
    • Network Address: Combining IP with subnet mask.
    • Broadcast Address: Using chart to find boundaries.
  3. Determine Usable IPs: Add/subtract one from network/broadcast addresses respectively.

Example Calculations

  • 165.245.12.88/24:

    • Network address: 165.245.12.0
    • Broadcast address: 165.245.12.255
    • First usable IP: 165.245.12.1
    • Last usable IP: 165.245.12.254

  • 165.245.12.88/26:

    • Convert /26: Fourth octet 192 (255.255.255.192)
    • Network address: 165.245.12.64
    • Broadcast address: 165.245.12.127
    • First usable IP: 165.245.12.65
    • Last usable IP: 165.245.12.126

Detailed Examples

  • /20 Subnet:

    • Network address: 165.245.0.0
    • Broadcast address: 165.245.15.255
    • First usable IP: 165.245.0.1
    • Last usable IP: 165.245.15.254

  • /11 Subnet:

    • Network address: 18.160.0.0
    • Broadcast address: 18.191.255.255
    • First usable IP: 18.160.0.1
    • Last usable IP: 18.191.255.254

Exam Preparation Tips

  • Chart Practice: Write/type charts before exams.
  • Testing Center Tools: Use laminated paper/whiteboards.
  • Dry Erase Markers: Bring a fine tip marker for clarity.

Conclusion

  • Find Your Method: Mix and match methods for best personal fit.
  • Practice: Essential for speed and accuracy in exams.
  • Adaptability: Choose tools and processes that work under test conditions.

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