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Module 1.2 - Network Math [Sep. 15th, 2007|09:19 am]
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Section 1.2.1 - Computers work with and store data but using switches. Switches are either ON (1) or OFF (0). We use decimal number system, computers use the binary number system. Sometimes binary numbers are converted to hexidecimal numbers.

Section 1.2.2 -
Bit (b)
Byte (B)
Kilobyte (KB)
Megabyte (MB)
Gigabyte (GB)
Terabyte (TB)

The value range of a byte is 0 to 255.

Section 1.2.3 - Base 10 uses 10 symbols, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9.

10^0=1
10^1=10
10^2=100
10^3=1000
10^4=10,000
10^5=100,000
10^6=1,000,000
10^7=10,000,000
10^8=100,000,000
10^9=1,000,000,000

Section 1.2.4 - The 2 system has 2 symbols, 1 and 0.

Example: 10110 in binary is equal to 16 in decimal.

...128 64 32 16 8 4 2 1 - Read from right to left.

Section 1.2.5 - Conversion in pretty simple once you get the hang of it, it can take some practicce though since we're so used to working with the decimal system.

Section 1.2.6 - More conversion.

Example: 01110000 is equal to 112 in decimal.

Section 1.2.7 - Dotted decimal notation. Currently IP addresses are assigned to every computer on the Internet. They're 32-bits. First the binary number is split into four groups of 8 binary digits and then converted into a decimal equivelent.

11001000 01110010 00000110 00110011
200.114.6.51

10000000 01011101 00001111 10101010
128.95.15.170

Section 1.2.8 - The hexidecimal number system is base 16. It's commonly used to represent binary numbers in a more readable format. Cisco router have a configuration register that is 16 bit long. For example, 00100000100000010 coould be represented as 0x2102 in hexidecimal format. Remember to include the 0x for hexidecimal. It uses the symbols 0-9 and A-F.

Section 1.2.9 - Boolean logic is based on digital circutry. It accepts one or two incoming voltages. It's either ON or OFF. They're either a 1 or a 0. Boolean logic uses AND, OR and NOT.

NOT will take the value and reverse it so that 0 will becomes 1 and 1 becomes 0.

AND will compare the 2 values and if both values are 1 it equals one, if there's a 0 for either of the values it equals 0.

The OR operation looks at the values and if there's a 1 it equals 1, if they're both 0 it equals 0.

The two networking operations that use Boolean logic are subnetwork and wildcard masking.
Section 1.2.10 - When IP addresses are assigned some of the bits on the left side represent a network. The bits that are left over identify the computer in the network. To help determine how the address get splits a second address called a subnet mask is assigned.

10.34.23.134
255.255.0.0

Network portion of IP is 10.34.0.0

My Note - I think I am actually starting to understand how this all works. I used to be quite confused about it all, but it's not to bad anymore :)
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