Dear RHSReddy,
      The questions you are posting are already in
AllInterview testing category.Kindly search it and you will
get the answers for the questions posted by you.
thanks

Black box testing is a build level testing technique to 
validate the internal processing depends on external 
interface.
  When we have to validate an application build the  
testing team validates through a set of black box testing 
techniques:

1.usability testing:whether it is user friendly or not...
2.Functional testing:It is mandatory as we have to meet 
correctness in every functionality wrt to customer 
reqirements
3.Performance testing:we concentrate on speed of processing
4.Security testing:we concentrate on the privacy to user 
operations....like authorisation,access 
control,encryption/decryption...etc.,

The blck box test techniques are 
1. Equivalence partioning (EP)
2. Boundary Value analysis(BVA)
3. Error guessing.
Some of the testing types followed in testing 
are,funtionality testing and non functionlity testing

Muralidharan

dharanmu@yahoo.com

Block box testing is nothing but funcnality testing. Block 
box testing is done by the testers.
 It focuses on the funcnality rather then the programming.

These testing are done by the user perspective.
In these blockbox testing some of these aspects will be 
considered.
Incorrect initialization

Testing techinique can be used to effectively desgin 
efficient test cases.These techinique can be grouped into 
blockbox and white box testing.
 BlockBox testing techiniques:
when creating block box test cases , the input data used is 
critical. Three successful techiniques or managing the 
amount of input sata reuires include:

1.Equivalance partitioning.
2. Boundary Analysis.
3.Error guessing.

EQUIVALANCE PARTITIONING:
Euivalance partitioning is a techinique for testing 
equivalance classes rather than undertaking exhaustive 
testing of each value of the larger class. for example
 a program which edit credit limits within a given range 
(1,000 -1,500) would have three equivalance classes;
< 1,000 ( invalid)
Between 1,000 and 1,500 ( valid)
> 1,500 ( in valid)

BOUNDARY ANALYSIS:
A techinique that consist of developing test cases and data 
that focus on the input and output boundaries of a given 
function. In same credit limit example, boundary analysis 
would test:

Low boundary  +/- one(999 and 1,001)
on the boundary ( 1,000 and 1, 500)
Upper boundary +/- one(1,499 and 1,501)

ERROR GUESSING:
 Test cases can be developed based upon the intuition and 
experience of the tester . For example in an example where 
one of the inputs is the date, a tester may try february 
29, 2000