Why an address looks like 192.168.1.20
People write an address as four numbers with dots, like 192.168.1.20. But a computer does not see it that way.
To a computer it is 32 ones and zeros. Each of the four numbers is really eight ones and zeros.
To plan addresses, you must move between these number systems.
Key words
| Word | What it means |
|---|---|
| Network | computers and devices joined together so they can share data |
| IP address | the number that names a device on a network |
| Number system | a way of writing numbers using a fixed set of digits |
| Decimal | the system we use every day, with ten digits, 0 to 9 |
| Binary | a system with two digits, 0 and 1 |
| Octal | a system with eight digits, 0 to 7 |
| Hexadecimal | a system with sixteen digits, 0 to 9 and then A to F |
| Bit | one binary digit, a 0 or a 1 |
| Byte | eight bits together |
| Place value | what a digit is worth because of where it sits in the number |
| Base | how many digits a number system has |
| Subnetting | splitting one network into smaller networks |
The cells students fill in are left blank in this preview.
By the end of this lesson
Note
I can say where binary, hex, decimal and octal are used in a network, and change small whole numbers between them using a table.
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3 questionsYour answers are marked here and are not kept. A college account keeps every student’s marks.
Four systems, four bases
The base is how many digits the system has.
Decimal is base 10. Binary is base 2. Octal is base 8. Hexadecimal, or hex, is base 16.
Hex needs sixteen digits, but we only have ten figures. So it uses the letters A to F for ten to fifteen.
The same numbers: 0 to 7
| Decimal | Binary | Octal | Hex |
|---|---|---|---|
| 0 | 0000 | 0 | 0 |
| 1 | 0001 | 1 | 1 |
| 2 | 0010 | 2 | 2 |
| 3 | 0011 | 3 | 3 |
| 4 | 0100 | 4 | 4 |
| 5 | 0101 | 5 | 5 |
| 6 | 0110 | 6 | 6 |
| 7 | 0111 | 7 | 7 |
The cells students fill in are left blank in this preview.
The same numbers: 8 to 15
| Decimal | Binary | Octal | Hex |
|---|---|---|---|
| 8 | 1000 | 10 | 8 |
| 9 | 1001 | 11 | 9 |
| 10 | 1010 | 12 | A |
| 11 | 1011 | 13 | B |
| 12 | 1100 | 14 | C |
| 13 | 1101 | 15 | D |
| 14 | 1110 | 16 | E |
| 15 | 1111 | 17 | F |
The cells students fill in are left blank in this preview.
Check
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4 questionsYour answers are marked here and are not kept. A college account keeps every student’s marks.