A protocol is set of rules that governs the data communication it specifies the structure, meaning and timing of communication the basic elements of protocol are
Syntax semantics and timing
Syntex specifies format or structure of the data packet
Semantic specifies meaning of each section of bits
Timing is specified when to start and how fast to send the data for communicate

Flow control

Flow control so control specifies the direction of data flow it can be three types simplex half duplex full duplex duplex
Incept in simplex data always flows one Direction like whenever a user keyboards button display on monitor sohar information flow is always from keyboard to monitor
Half duplex in half duplex data flow in both direction at a time
Full duplex in this mode data can simultaneously flow in both direction

Types of networks

Based on distance computer network is divided into three categories
Local area network
Metropolitan Area Network
Wide area network
Range of local area network is within few kilometres like 5 to 10 kilometre if two computers are connected within a room then it is a local area network and it can span in college campus
Man the range of man is approx 1 City television service provider which which span within one City approx 50 to 70 kilometres
When wide area network it can span in one country power in multiple countries like telephone service provider

Computer networks

A network is interconnection of two or more devices these devices are also known as nodes . a node can be a computer printer or any device capable of sending and receiving data generated by other nodes on the network

Applications of network

  • Resource sharing
    • hardware resources like printer disc
    • Software resources like application software
  • Information sharing easy accessible from anywhere like file data bases
  • Search capabilities like www
  • Communication email message sending chatting
  • Remote computing
  • Distributed processing
  • Game playing
  • Online transaction

Transmission Technology
There are two types of Transmission Technology network point to point network and broadcast network in broadcast network a single communication link shared by all the Machines the network.
Point to point network Two computers are connected at the both end of linked and is dedicated only to those two computers

updating user login password

SET PASSWORD FOR ‘user’@’localhost’ = PASSWORD( ‘NewPassword’ );

SHOW VARIABLES LIKE ‘validate_password%’;

# SET GLOBAL validate_password_length = 5;
# SET GLOBAL validate_password_number_count = 0;
# SET GLOBAL validate_password_mixed_case_count = 0;
# SET GLOBAL validate_password_special_char_count = 0;


It is a passive real number other than a^m = n
We write m=log_a x

10^3 =10004 then we can write log_{10} 1000 = 3
2^{-3} =\frac{1}{8} then we can write log_2 \frac{1}{8} = -3

Properties of logarithms

log_a (xy) = log_a x +log_a y
log_a (\frac{x}{y}) = log_a x - log_a y
log_x x = 1
Example 2^1=2 so we can write log_2 2 = 1
log_a 1 = 0
Example 5^0=1 in logarithm form log_5 1 = 0

log_a x^p = p(log_a x)
log_a x  = 1/log_x^a
log_a x = \frac{log_b^x}{log_b^a}   = \frac{log_⁡x}{log_⁡a}

Logarithms to the base 10 are known as common logarithms. When base is not mentioned it is taken as 10.
Characteristic – when the number is greater than 1 – the characteristic is one less from the number of digit in the left of the decimal point in the given number.

(\overline{48}) ̅.48= 1 (\overline{6185}) ̅.41 = 3
When the number is less than 1 one more than the number of zero between the decimal point & the 1st significant digit of the number & it is negative.
0.518 = -1 0.0347 = etc.

Log table-
10^{.001} = 10^{1/1000}   = 1.002305.238
10^{0.02} = 1.584293192
10^{0.01} = 10^{1/100}    = 1.023292992
10^{0.6} =3.981071706
10^{0.5} = 10^{\frac{1}{2}}= 3.16227766
10^{0.3} =  1.995262215
10^{0.1} = 10^{\frac{1}{10} =  1.258925412
10^{0.7} =  5.0118872336

Simple and compound interest

Simple interest

SI = P*R*T/100

P= principal amount
R = rate/unit
T = time/year month day etc.

Compound interest

CI = P(1+\frac{R}{100})^n
P= principal amount
R= rate/unit
T= time unit

Where rate are difference for different unit or time.

Than C.I = p(1+\frac{R1}{100}) (1+\frac{R2}{100}) (1+\frac{R3}{100}) ……….

Present worth of Rs x lac in year hence is given by present worth=

Alligation Or Mixture

Alligation- the rate to find the ratio in which two or more ingredients at the given price.must be mixed to produce a mixer of a desired price.
Mean price- the cost price of a unit remobilty of the mix are is called mean price.

Rule of allegation \frac{(quantity of cheaper)}{(quantity of deaver)}= \frac{(c.p of deaver)-(mean price)}{(mean price)-(c.p of cheaper)}


cheaper quantity: dearer quantity= (d-m): (m-c)

A container of x unit capacity of liquid, when we taken out some unit say x replaced by water, when we do the same operation n times.
quantity of pure liquid= [x(1-x^1/x)n]unit

Boat and Stream

if the speed of a boat in still water is u km/h & the speed of the streams of v km/h than-
speed towards downstream- (u+v) km/h
Speed towards up stream- (u-v) km/h
if the speed of boat in downstream u km/h and in upstream v km/h
than speed in still water-\frac{1}{2}(u+v) km/h
rate or speed of stream=\frac{1}{2}(a-b) km/h

Time and Distance

speed = \frac{distance}{time}

X km/hour = x  * \frac{1000 metres}{60×60 second}  =   x*\frac{5}{18}  m/sec

If the ratio of the speed of A & B is a:b then the ratio of time taken by them to cover the same distance is \frac{1}{a} :\frac{1}{b} = b:a
“The time taken for covering a certain distance is increasingly proportional to the speed.”
Similarly time taken to finish a work is the inversed proportional to the number of working unit
When by A, cover a certain distance at x km/h & b cover the same distance at y km/h than the average speed of both during the whole journey
journey = (\frac{2xy}{(x+y)})km/h

Difference distance by two moving body in same direction with ‘u’ m/s and ‘v’ m/s
u>v then their relatives speed = (u-v) m/s
u>v in opposite direction they cross to each other = \frac{(a+b)}{(u+v)} second
(With length of a & b meter)
u>v in same direction cross to each other = \frac{(a+b)}{(u-v)} second
if two bodies start at the same time from station A & b to words each other . they have taken time a & b second to reaching A to B & B to A .
then A’s speed: √b:√a