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Aisalkyn Aidarova
Aisalkyn Aidarova

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Sizes in Computers (VERY IMPORTANT FOUNDATION)

#beginners #computerscience #networking #tutorial

Everything in networking is based on bits → bytes → IP

What is a BIT?

👉 A bit is the smallest unit of data

bit = 0 or 1
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  • 0 = OFF
  • 1 = ON

What is a BYTE?

👉 A byte = 8 bits

1 byte = 8 bits
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Example:

10101010  → 1 byte
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What is an OCTET?

👉 An octet = 8 bits (same as byte)

In networking, we say:

  • byte → general computing
  • octet → networking (IP addresses)

🎯 KEY IDEA 

1 octet = 8 bits = numbers from 0 to 255
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🎓 2. Why 0–255?

Because:

2^8 = 256

👉 So:

0 to 255 = 256 values
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🎓 3. Structure of IP Address

Example:

192.168.1.10
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This has 4 octets:

[192] [168] [1] [10]
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Each one = 8 bits

Total:

4 × 8 = 32 bits
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🎓 4. The “BOX METHOD” (This is what you asked)

This is how you convert numbers like 192 into bits

Step 1 — Draw boxes

Each octet has 8 boxes (bits)

128  64  32  16  8  4  2  1
[  ] [  ] [  ] [  ] [ ] [ ] [ ] [ ]
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👉 These numbers are powers of 2

🎓 5. Example: Convert 192

We need to make 192 using these numbers

Step-by-step: 

192 - 128 = 64 → use 128 → put 1
64 - 64 = 0   → use 64  → put 1
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Remaining = 0 → rest are 0

Final boxes: 

128  64  32  16  8  4  2  1
 1    1   0   0   0  0  0  0
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Final answer: 

192 = 11000000
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🎓 6. Example: Convert 168

Step-by-step: 

168 - 128 = 40 → 1
40 - 32 = 8   → 1
8 - 8 = 0     → 1
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Boxes: 

128  64  32  16  8  4  2  1
 1    0   1   0   1  0  0  0
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Final: 

168 = 10101000
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🎓 7. Example: Convert 1 

00000001
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🎓 8. Example: Convert 0 

00000000
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🎓 9. Full IP in Binary 

192.168.1.10 =
11000000.10101000.00000001.00001010
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🎓 10. VERY SIMPLE MEMORY TRICK

👉 Think:

Big numbers → left side
Small numbers → right side
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🎓 11. Shortcut Table (Memorize This)

Decimal Binary
128 10000000
192 11000000
224 11100000
240 11110000
248 11111000
252 11111100
255 11111111

👉 These are used in subnet masks

🎓 12. Why This Matters

You need this to understand:

  • subnet mask
  • network vs host
  • AWS VPC
  • CIDR

🎓 FINAL SUMMARY

👉 bit = 0 or 1
👉 8 bits = 1 byte = 1 octet
👉 octet = 0–255
👉 IP = 4 octets = 32 bits
👉 boxes = powers of 2
👉 fill with 1s to reach number

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