Sizes in Computers (VERY IMPORTANT FOUNDATION)

[MyrinNew]

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

• 0 = OFF
• 1 = ON

What is a BYTE?

👉 A byte = 8 bits






1 byte = 8 bits







Example:






10101010 → 1 byte










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










🎓 2. Why 0–255?

Because:


2^8 = 256


👉 So:






0 to 255 = 256 values










🎓 3. Structure of IP Address

Example:






192.168.1.10







This has 4 octets:






[192] [168] [1] [10]







Each one = 8 bits


Total:






4 × 8 = 32 bits










🎓 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
[ ] [ ] [ ] [ ] [ ] [ ] [ ] [ ]







👉 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







Remaining = 0 → rest are 0





Final boxes:





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










Final answer:





192 = 11000000










🎓 6. Example: Convert 168




Step-by-step:





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










Boxes:





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










Final:





168 = 10101000










🎓 7. Example: Convert 1





00000001










🎓 8. Example: Convert 0





00000000










🎓 9. Full IP in Binary





192.168.1.10 =
11000000.10101000.00000001.00001010










🎓 10. VERY SIMPLE MEMORY TRICK

👉 Think:






Big numbers → left side
Small numbers → right side










🎓 11. Shortcut Table (Memorize This)

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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